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Chapter 7The Pelvis: Part II—The Pelvic Cavity A 62-year-old man visited his physician for an annual physical examination. He appeared to be in very good health and had no complaints. A general examination revealed nothing abnormal. The physician then told the patient that he was about to perform a rectal examination. At first the patient objected, saying that he did not feel it was necessary because nothing abnormal was found a year ago. The physician persisted and finally the patient agreed to the examination. A small hard nodule was found projecting from the posterior surface of the prostate. No other abnormalities were discovered. The patient was informed of the findings, and the possibility that the nodule was malignant was explained. The patient was very upset, especially because he had no abnormal urinary symptoms. Additional laboratory and radiologic tests were performed, and the prostate-specific antigen (PSA) level in the blood was found to be well above the normal range. No evidence of pelvic lymphatic enlargement was seen on pelvic computed tomography (CT) scans and no evidence of bone metastases was seen on bone scans. A diagnosis of early cancer of the prostate was made and was later confirmed by a needle biopsy of prostatic tissue through the anterior wall of the rectum. This case illustrates how a physician in general practice who has good knowledge of the relevant anatomic features of the pelvis can recognize an abnormal prostate when it is palpated through the anterior rectal wall. This patient later had the prostate removed, and the prognosis was excellent. P.338
Chapter Objectives

  • The pelvic cavity contains the lower ends of the intestinal and urinary tracts and the internal organs of reproduction as well as their nerve supply, blood supply, and lymphatic drainage.
  • The organs project up into the peritoneal cavity, causing the peritoneum to be draped over them in folds, producing important fossae that are the sites for the accumulation of blood and pus in different types of pelvic disease.
  • The physician is often confronted with problems involving infections, injuries, and prolapses of the rectum, uterus, and vagina.
  • Emergency situations involving the bladder, the pregnant uterus, ectopic pregnancy, spontaneous abortion, and acute pelvic inflammatory disease are examples of problems found in the female.
  • The urinary bladder and the prostate in the male are frequent sites of disease.
  • The purpose of this chapter is to consider the important anatomy relative to common clinical conditions involving the pelvic organs.

Basic Anatomy The pelvic cavity, or cavity of the true pelvis, can be defined as the area between the pelvic inlet and the pelvic outlet. It is customary to subdivide it by the pelvic diaphragm into the main pelvic cavity above and the perineum below (Fig. 7-1). This chapter is concerned with the contents of the main pelvic cavity. A detailed description of the perineum is given in Chapter 8. Contents of the Pelvic Cavity Sigmoid Colon Location and Description The sigmoid colon is 10 to 15 in. (25 to 38 cm) long and begins as a continuation of the descending colon in front of the pelvic brim. Below, it becomes continuous with the rectum in front of the third sacral vertebra. The sigmoid colon is mobile and hangs down into the pelvic cavity in the form of a loop. The sigmoid colon is attached to the posterior pelvic wall by the fan-shaped sigmoid mesocolon. Relations

  • Anteriorly: In the male, the urinary bladder; in the female, the posterior surface of the uterus and the upper part of the vagina
  • Posteriorly: The rectum and the sacrum. The sigmoid colon is also related to the lower coils of the terminal part of the ileum.

Blood Supply Arteries Sigmoid branches of the inferior mesenteric artery. Veins The veins drain into the inferior mesenteric vein, which joins the portal venous system. Lymph Drainage The lymph drains into nodes along the course of the sigmoid arteries; from these nodes, the lymph travels to the inferior mesenteric nodes. Nerve Supply The sympathetic and parasympathetic nerves from the inferior hypogastric plexuses. P.339
Clinical Notes Variation in Length and Location of the Sigmoid Colon The sigmoid colon shows great variation in length and may measure as much as 36 in. (91 cm). In the young child, because the pelvis is small, this segment of the colon may lie mainly in the abdomen. Cancer of the Sigmoid Colon The sigmoid colon is a common site for cancer of the large bowel. Because the lymphatic vessels of this segment of the colon drain ultimately into the inferior mesenteric nodes, it follows that an extensive resection of the gut and its associated lymphatic field is necessary to extirpate the growth and its local lymphatic metastases. The colon is removed from the left colic flexure to the distal end of the sigmoid colon, and the transverse colon is anastomosed to the rectum. Volvulus Because of its extreme mobility, the sigmoid colon sometimes rotates around its mesentery. This may correct itself spontaneously, or the rotation may continue until the blood supply of the gut is cut off completely. The rotation commonly occurs in a counterclockwise direction and is referred to as volvulus. Diverticula Diverticula of the mucous membrane along the course of the arteries supplying the sigmoid colon is a common clinical condition and is described on page 236. In patients with diverticulitis or ulcerative colitis, the sigmoid colon may become adherent to the bladder, rectum, ileum, or ureter and produce an internal fistula. Sigmoidoscopy Because the sigmoid colon lies only a short distance from the anus (6.5 in. [17 cm]), it is possible to examine the mucous membrane under direct vision for pathologic conditions. A flexible tube fitted with lenses and illuminated internally is introduced through the anus and carefully passed up through the anal canal, rectum, sigmoid colon, and descending colon. This examination, called sigmoidoscopy, can be carried out without an anesthetic in an outpatient clinic. Biopsy specimens of the mucous membrane can be obtained through this instrument. Anatomic Facts Relevant to Sigmoidoscopy

  • The patient is placed in the left lateral position with the left knee flexed and the right knee extended (Fig. 7-2). Alternatively, the patient is placed kneeling in the knee–chest position.
  • The sigmoidoscope is gently inserted into the anus and anal canal in the direction of the umbilicus to ensure that the instrument passes along the long axis of the canal. Gentle but firm pressure is applied to overcome the resistance of the anal sphincters (Fig. 7-3).
  • After a distance of about 1.5 in. (4 cm), the instrument enters the ampulla of the rectum. At this point, the tip of the sigmoidoscope should be directed posteriorly in the midline to follow the sacral curve of the rectum (Fig. 7-2).
  • Slow advancement is made under direct vision. Some slight side-to-side movement may be necessary to bypass the transverse rectal folds.
  • At approximately 6.5 in. (16.25 cm) from the anal margin, the rectosigmoid junction will be reached. The sigmoid colon here bends forward and to the left, and the lumen appears to end in a blind cul-de-sac. To negotiate this angulation, the tip of the sigmoidoscope must be directed anteriorly and to the patient’s left side. This maneuver can cause some discomfort in the anal canal from distortion of the anal sphincters by the shaft of the sigmoidoscope. Another possibility is that the point of the instrument may stretch the wall of the colon, giving rise to colicky pain in the lower abdomen.
  • Once the instrument has entered the sigmoid colon, it should be possible to pass it smoothly along its full extent and, using the full length of the sigmoidoscope, enter the descending colon.
  • The sigmoidoscope may now be slowly withdrawn, carefully inspecting the mucous membrane. The normal rectal and colonic mucous membrane is smooth and glistening and pale pink with an orange tinge, and blood vessels in the submucosa can be clearly seen. The mucous membrane is supple and moves easily over the end of the sigmoidoscope.

Anatomy of Complications of Sigmoidoscopy Perforation of the bowel at the rectosigmoid junction can occur. This is almost invariably caused by the operator failing to negotiate carefully the curve between the rectum and the sigmoid colon. In some patients, the curve is in the form of an acute angulation, which may frustrate the overzealous advancement of the sigmoidoscope. Perforation of the sigmoid colon results in the escape of colonic contents into the peritoneal cavity. Colonoscopy Direct inspection of the lining of the entire colon including the cecum has become an important weapon in the early diagnosis of mucosal polyps and large bowel cancer in recent years. Not only can the colon be observed and suspicious areas photographed for future reference, but also biopsy specimens can be removed for pathologic examination. For the diagnosis of early cancer, physicians previously relied almost entirely on rectal examination, sigmoidoscopy, and the detection of occult blood in the feces. The disadvantage of colonoscopy is the high cost (see Fig. 5-37). Following a regime in which the large bowel is thoroughly washed out, the patient is relaxed under a light anesthetic. The flexible endoscopic tube is introduced through the anus into the anal canal, rectum, and colon. Colonoscopy can also be used in the diagnosis and treatment of ulcerative colitis and Crohn’s disease. Colostomy The sigmoid colon is often selected as a site for performing a colostomy in patients with carcinoma of the rectum. Its mobility allows the surgeon to bring out a loop of colon, with its blood supply intact, through a small incision in the left iliac region of the anterior abdominal wall. Its mobility also makes it suitable for implantation of the ureters after surgical removal of the bladder. P.340

Figure 7-1 Coronal section through the thorax, abdomen, and pelvis showing the thoracic, abdominal, and pelvic cavities and the perineum.
Figure 7-2 Sigmoidoscopy. A. Patient in the left lateral position with the left knee flexed and the right knee extended. B. Sagittal section of the male pelvis showing the positions (1, 2, and 3) of the tube of the sigmoidoscope relative to the patient as it ascends the anal canal and rectum. The area of discomfort or pain experienced by the patient as the tube is negotiated around the bend into the sigmoid colon is referred to the skin of the anterior abdominal wall below the umbilicus.

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Figure 7-3 Coronal section through the pelvis showing the rectum and the pelvic floor.

Rectum Location and Description The rectum is about 5 in. (13 cm) long and begins in front of the third sacral vertebra as a continuation of the sigmoid colon. It passes downward, following the curve of the sacrum and coccyx, and ends in front of the tip of the coccyx by piercing the pelvic diaphragm and becoming continuous with the anal canal. The lower part of the rectum is dilated to form the rectal ampulla. The rectum deviates to the left, but it quickly returns to the median plane (Fig. 7-3). On lateral view, the rectum follows the anterior concavity of the sacrum before bending downward and backward at its junction with the anal canal (Fig. 7-4). The puborectalis portion of the levator ani muscles forms a sling (see page 318) at the junction of the rectum with the anal canal and pulls this part of the bowel forward, producing the anorectal angle. The peritoneum covers the anterior and lateral surfaces of the first third of the rectum and only the anterior surface of the middle third, leaving the lower third devoid of peritoneum (Figs. 7-4 and 7-5). The muscular coat of the rectum is arranged in the usual outer longitudinal and inner circular layers of smooth muscle. The three teniae coli of the sigmoid colon, however, come together so that the longitudinal fibers form a broad band on the anterior and posterior surfaces of the rectum. The mucous membrane of the rectum, together with the circular muscle layer, forms two or three semicircular permanent folds called the transverse folds of the rectum (Fig. 7-3); they vary in position. Relations

  • Posteriorly: The rectum is in contact with the sacrum and coccyx; the piriformis, coccygeus, and levatores ani muscles; the sacral plexus; and the sympathetic trunks (see Fig. 6-18).
  • Anteriorly: In the male, the upper two thirds of the rectum, which is covered by peritoneum, is related to the sigmoid colon and coils of ileum that occupy the rectovesical pouch. The lower third of the rectum, which is devoid of peritoneum, is related to the posterior surface of the bladder, to the termination of the vas deferens and the seminal vesicles on each side, and to the prostate (Fig. 7-4).

In the female, the upper two thirds of the rectum, which is covered by peritoneum, is related to the sigmoid colon and coils of ileum that occupy the rectouterine pouch (pouch of Douglas). The lower third of the rectum, which is devoid of peritoneum, is related to the posterior surface of the vagina (Fig. 7-5). P.342

Figure 7-4 Sagittal section of the male pelvis.
Figure 7-5 Sagittal section of the female pelvis.

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Blood Supply Arteries The superior, middle, and inferior rectal arteries (Fig. 7-6) supply the rectum. The superior rectal artery is a direct continuation of the inferior mesenteric artery and is the chief artery supplying the mucous membrane. It enters the pelvis by descending in the root of the sigmoid mesocolon and divides into right and left branches, which pierce the muscular coat and supply the mucous membrane. They anastomose with one another and with the middle and inferior rectal arteries.

Figure 7-6 A. Blood supply to the rectum. B. The transverse folds of the rectum as seen through a sigmoidoscope.

The middle rectal artery is a small branch of the internal iliac artery and is distributed mainly to the muscular coat. The inferior rectal artery is a branch of the internal pudendal artery in the perineum. It anastomoses with the middle rectal artery at the anorectal junction. Veins The veins of the rectum correspond to the arteries. The superior rectal vein is a tributary of the portal circulation and drains into the inferior mesenteric vein. The middle and inferior rectal veins drain into the internal iliac and internal pudendal veins, respectively. The union between P.344
the rectal veins forms an important portal–systemic anastomosis (see Chapter 5). Lymph Drainage The lymph vessels of the rectum drain first into the pararectal nodes and then into inferior mesenteric nodes. Lymph vessels from the lower part of the rectum follow the middle rectal artery to the internal iliac nodes. Nerve Supply The nerve supply is from the sympathetic and parasympathetic nerves from the inferior hypogastric plexuses. The rectum is sensitive only to stretch. Clinical Notes Rectal Curves and Mucosal Folds The anteroposterior flexure of the rectum, as it follows the curvature of the sacrum and coccyx, and the lateral flexures must be remembered when one is passing a sigmoidoscope to avoid causing the patient unnecessary discomfort. The crescentic transverse mucosal folds of the rectum must also be borne in mind when passing an instrument into the rectum. It is thought that these folds serve to support the weight of the feces and to prevent excessive distention of the rectal ampulla. Blood Supply and Internal Hemorrhoids The chief arterial supply to the rectum is from the superior rectal artery, a continuation of the inferior mesenteric artery. In front of the third sacral vertebra, the artery divides into right and left branches. Halfway down the rectum, the right branch divides into an anterior and a posterior branch. The tributaries of the superior rectal vein are arranged in a similar manner, so that it is not surprising to find that internal hemorrhoids are arranged in three groups (see Chapter 8): two on the right side of the lower rectum and anal canal and one on the left. Partial and Complete Prolapse of the Rectum Partial and complete prolapses of the rectum through the anus are relatively common clinical conditions. In partial prolapse, the rectal mucous membrane and submucous coat protrude for a short distance outside the anus (Fig. 7-7). In complete prolapse, the whole thickness of the rectal wall protrudes through the anus. In both conditions, many causative factors may be involved. However, damage to the levatores ani muscles as the result of childbirth and poor muscle tone in the aged are important contributing factors. A complete rectal prolapse may be regarded as a sliding hernia through the pelvic diaphragm. Cancer of the Rectum Cancer (carcinoma) of the rectum is a common clinical finding that remains localized to the rectal wall for a considerable time. At first, it tends to spread locally in the lymphatics around the circumference of the bowel. Later, it spreads upward and laterally along the lymph vessels, following the superior rectal and middle rectal arteries. Venous spread occurs late, and because the superior rectal vein is a tributary of the portal vein, the liver is a common site for secondary deposits. Once the malignant tumor has extended beyond the confines of the rectal wall, knowledge of the anatomic relations of the rectum will enable a physician to assess the structures and organs likely to be involved. In both sexes, a posterior penetration involves the sacral plexus and can cause severe intractable pain down the leg in the distribution of the sciatic nerve. A lateral penetration may involve the ureter. An anterior penetration in the male may involve the prostate, seminal vesicles, or bladder; in the female, the vagina and uterus may be invaded.

Figure 7-7 Coronal section of the rectum and anal canal. A. Incomplete rectal (mucosal) prolapse. B. Complete rectal prolapse.

It is clear from the anatomic features of the rectum and its lymph drainage that a wide resection of the rectum with its lymphatic field offers the best chance of cure. When the tumor has spread to contiguous organs and is of a low grade of malignancy, some form of pelvic evisceration may be justifiable. It is most important for a medical student to remember that the interior of the lower part of the rectum can be examined by a gloved index finger introduced through the anal canal. The anal canal is about 1.5 in. (4 cm) long so that the pulp of the index finger can easily feel the mucous membrane lining the lower end of the rectum. Most cancers of the rectum can be diagnosed by this means. This examination can be extended in both sexes by placing the other hand on the lower part of the anterior abdominal wall. With the bladder empty, the anterior rectal wall can be examined bimanually. In the female, the placing of one finger in the vagina and another in the rectum may enable the physician to make a thorough examination of the lower part of the anterior rectal wall. Rectal Injuries The management of penetrating rectal injuries will be determined by the site of penetration relative to the peritoneal covering. The upper third of the rectum is covered on the anterior and lateral surfaces by peritoneum, the middle third is covered only on its anterior surface, and the lower third is devoid of a peritoneal covering (Figs. 7-3, 7-4, and 7-5). The treatment of penetration of the intraperitoneal portion of the rectum is identical to that of the colon, because the peritoneal cavity has been violated. In the case of penetration of the extraperitoneal portion, the rectum is treated by diverting the feces through a temporary abdominal colostomy, administering antibiotics, and repairing and draining the tissue in front of the sacrum. Pelvic Appendix If an inflamed appendix is hanging down into the pelvis, abdominal tenderness in the right iliac region may not be felt, but deep tenderness may be experienced above the symphysis pubis. Rectal examination (or vaginal examination in the female) may reveal tenderness of the peritoneum in the pelvis on the right side. If such an inflamed appendix perforates, a localized pelvic peritonitis may result. P.345
Embryologic Notes Development of the Distal Part of the Large Bowel The left colic flexure, descending colon, sigmoid colon, rectum, and upper half of the anal canal are developed from the hindgut. Distally, this terminates as a blind sac of entoderm, which is in contact with a shallow ectodermal depression called the proctodeum. The apposed layers of ectoderm and entoderm form the cloacal membrane, which separates the cavity of the hindgut from the surface (Fig. 7-8). The hindgut sends off a diverticulum, the allantois, that passes into the umbilical cord. Distal to the allantois, the hindgut dilates to form the entodermal cloaca (Fig. 7-8). In the interval between the allantois and the hindgut, a wedge of mesenchyme invaginates the entoderm. With continued proliferation of the mesenchyme, a septum is formed that grows inferiorly and divides the cloaca into anterior and posterior parts. The septum is called the urorectal septum, the anterior part of the cloaca becomes the primitive bladder and the urogenital sinus, and the posterior part of the cloaca forms the anorectal canal. On reaching the cloacal membrane, the urorectal septum fuses with it and forms the future perineal body (Fig. 7-8). The fates of the primitive bladder and the urogenital sinus in both sexes are considered in detail on page 357. The anorectal canal forms the rectum and the superior half of the anal canal. The lining of the inferior half of the anal canal is formed from the ectoderm of the proctodeum (Fig. 7-9). The posterior part of the cloacal membrane breaks down so that the gut opens onto the surface of the embryo. Hindgut Artery The hindgut, which extends from the left colic flexure to halfway down the anal canal, is supplied by the inferior mesenteric artery (see Fig. 5-46). Here, a number of ventral branches of the aorta fuse to form a single artery. Meconium At full term, the large intestine is filled with a mixture of intestinal gland secretions, bile, and amniotic fluid. This substance is dark green in color and is called meconium. It starts to accumulate at 4 months and reaches the rectum at the fifth month. Primary Megacolon (Hirschsprung Disease) Hirschsprung disease shows a familial tendency and is more common in males than in females. Symptoms usually appear during the first few days after birth. The child fails to pass meconium, and the abdomen becomes enormously distended. The sigmoid colon is greatly distended and hypertrophied, while the rectum and anal canal are constricted (Fig. 7-10). It is the constricted segment of the bowel that causes the obstruction, and histologic examination reveals a complete failure of development of the parasympathetic ganglion cells in this region. The treatment is operative excision of the aganglionic segment of the bowel. P.346

Figure 7-8 Progressive stages (1–4) in the formation of the urorectal septum, which divides the cloaca into an anterior part (the primitive bladder and the urogenital sinus) and a posterior part (the anorectal canal).
Figure 7-9 Structure of the anal canal and its embryologic origin.

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Figure 7-10 Main characteristics of primary megacolon (Hirschsprung disease).

Pelvic Viscera in the Male The rectum, sigmoid colon, and terminal coils of ileum occupy the posterior part of the pelvic cavity in both sexes, as described above. The contents of the anterior part of the pelvic cavity in the male are described in the following sections. Ureters Each ureter is a muscular tube that extends from the kidney to the posterior surface of the bladder. Its abdominal course is described on page 266.

Figure 7-11 Right half of the pelvis showing relations of the ureter and vas deferens.

The ureter enters the pelvis by crossing the bifurcation of the common iliac artery in front of the sacroiliac joint. Each ureter then runs down the lateral wall of the pelvis in front of the internal iliac artery to the region of the ischial spine and turns forward to enter the lateral angle of the bladder (Fig. 7-11). Near its termination, it is crossed by the vas deferens. The ureter passes obliquely through the wall of the bladder for about 0.75 in. (1.9 cm) before opening into the bladder. Constrictions The ureter possesses three constrictions: where the renal pelvis joins the ureter in the abdomen, where it is kinked as P.348
it crosses the pelvic brim to enter the pelvis, and where it pierces the bladder wall. The blood supply, lymph drainage, and nerve supply of the ureter are described on page 266. Urinary Bladder Location and Description The urinary bladder is situated immediately behind the pubic bones (Fig. 7-4) within the pelvis. It stores urine and in the adult has a maximum capacity of about 500 mL. The bladder has a strong muscular wall. Its shape and relations vary according to the amount of urine that it contains. The empty bladder in the adult lies entirely within the pelvis; as the bladder fills, its superior wall rises up into the hypogastric region (Fig. 7-12). In the young child, the empty bladder projects above the pelvic inlet; later, when the pelvic cavity enlarges, the bladder sinks into the pelvis to take up the adult position.

Figure 7-12 A. Lateral view of the bladder. Note that the superior wall rises as the viscus fills with urine. Note also that the peritoneum covering the superior surface of the bladder is peeled off from the anterior abdominal wall as the bladder fills. B. Interior of the bladder in the male as seen from in front.

The empty bladder is pyramidal (Fig. 7-13), having an apex, a base, and a superior and two inferolateral surfaces; it also has a neck. The apex of the bladder points anteriorly and lies behind the upper margin of the symphysis pubis (Figs. 7-4 and 7-12). It is connected to the umbilicus by the median umbilical ligament (remains of urachus). The base, or posterior surface of the bladder, faces posteriorly and is triangular. The superolateral angles are joined by the ureters, and the inferior angle gives rise to the urethra (Fig. 7-13). The two vasa deferentia lie side by side on the posterior surface of the bladder and separate the seminal vesicles from each other (Fig. 7-13). The upper part of the P.349
posterior surface of the bladder is covered by peritoneum, which forms the anterior wall of the rectovesical pouch. The lower part of the posterior surface is separated from the rectum by the vasa deferentia, the seminal vesicles, and the rectovesical fascia (Fig. 7-4).

Figure 7-13 A. Lateral view of the bladder, prostate, and left seminal vesicle. B. Posterior view of the bladder, prostate, vasa deferentia, and seminal vesicles.

The superior surface of the bladder is covered with peritoneum and is related to coils of ileum or sigmoid colon (Fig. 7-4). Along the lateral margins of this surface, the peritoneum passes to the lateral pelvic walls. As the bladder fills, it becomes ovoid, and the superior surface bulges upward into the abdominal cavity. The peritoneal covering is peeled off the lower part of the anterior abdominal wall so that the bladder comes into direct contact with the anterior abdominal wall. The inferolateral surfaces are related in front to the retropubic pad of fat and the pubic bones. More posteriorly, they lie in contact with the obturator internus muscle above and the levator ani muscle below. The neck of the bladder lies inferiorly and rests on the upper surface of the prostate (Fig. 7-13). Here, the smooth muscle fibers of the bladder wall are continuous with those of the prostate. The neck of the bladder is held in position P.350
by the puboprostatic ligaments in the male; these are called the pubovesical ligaments in the female. These ligaments are thickenings of the pelvic fascia. When the bladder fills, the posterior surface and neck remain more or less unchanged in position, but the superior surface rises into the abdomen, as described in the previous paragraphs. The mucous membrane of the greater part of the empty bladder is thrown into folds that disappear when the bladder is full. The area of mucous membrane covering the internal surface of the base of the bladder is called the trigone. Here, the mucous membrane is always smooth, even when the viscus is empty (Fig. 7-12), because the mucous membrane is firmly adherent to the underlying muscular coat. The superior angles of the trigone correspond to the openings of the ureters, and the inferior angle to the internal urethral orifice (Fig. 7-12). The ureters pierce the bladder wall obliquely, and this provides a valvelike action, which prevents a reverse flow of urine toward the kidneys as the bladder fills. The trigone is limited above by a muscular ridge, which runs from the opening of one ureter to that of the other and is known as the interureteric ridge. The uvula vesicae is a small elevation situated immediately behind the urethral orifice, which is produced by the underlying median lobe of the prostate. The muscular coat of the bladder is composed of smooth muscle and is arranged as three layers of interlacing bundles known as the detrusor muscle. At the neck of the bladder, the circular component of the muscle coat is thickened to form the sphincter vesicae. Blood Supply Arteries The superior and inferior vesical arteries, branches of the internal iliac arteries. Veins The veins form the vesical venous plexus which drains into the internal iliac vein. Lymph Drainage Internal and external iliac nodes. Nerve Supply The inferior hypogastric plexuses. The sympathetic postganglionic fibers originate in the first and second lumbar ganglia and descend to the bladder via the hypogastric plexuses. The parasympathetic preganglionic fibers arise as the pelvic splanchnic nerves from the second, third, and fourth sacral nerves; they pass through the inferior hypogastric plexuses to reach the bladder wall, where they synapse with postganglionic neurons. Most afferent sensory fibers arising in the bladder reach the central nervous system via the pelvic splanchnic nerves. Some afferent fibers travel with the sympathetic nerves via the hypogastric plexuses and enter the first and second lumbar segments of the spinal cord. The sympathetic nerves* inhibit contraction of the detrusor muscle of the bladder wall and stimulate closure of the sphincter vesicae. The parasympathetic nerves stimulate contraction of the detrusor muscle of the bladder wall and inhibit the action of the sphincter vesicae. Micturition Micturition is a reflex action that, in the toilet-trained individual, is controlled by higher centers in the brain. The reflex is initiated when the volume of urine reaches about 300 mL; stretch receptors in the bladder wall are stimulated and transmit impulses to the central nervous system, and the individual has a conscious desire to micturate. Most afferent impulses pass up the pelvic splanchnic nerves and enter the second, third, and fourth sacral segments of the spinal cord (Fig. 7-14). Some afferent impulses travel with the sympathetic nerves via the hypogastric plexuses and enter the first and second lumbar segments of the spinal cord. Efferent parasympathetic impulses leave the cord from the second, third, and fourth sacral segments and pass via the parasympathetic preganglionic nerve fibers through the pelvic splanchnic nerves and the inferior hypogastric plexuses to the bladder wall, where they synapse with postganglionic neurons. By means of this nervous pathway, the smooth muscle of the bladder wall (the detrusor muscle) is made to contract, and the sphincter vesicae is made to relax. Efferent impulses also pass to the urethral sphincter via the pudendal nerve (S2, 3, and 4), and this undergoes relaxation. Once urine enters the urethra, additional afferent impulses pass to the spinal cord from the urethra and reinforce the reflex action. Micturition can be assisted by contraction of the abdominal muscles to raise the intra-abdominal and pelvic pressures and exert external pressure on the bladder. In young children, micturition is a simple reflex act and takes place whenever the bladder becomes distended. In the adult, this simple stretch reflex is inhibited by the activity of the cerebral cortex until the time and place for micturition are favorable. The inhibitory fibers pass downward with the corticospinal tracts to the second, third, and fourth sacral segments of the cord. Voluntary control of micturition is accomplished by contracting the sphincter urethrae, which closes the urethra; this is assisted by the sphincter vesicae, which compresses the bladder neck. Voluntary control of micturition is normally developed during the second or third year of life. P.351
Clinical Notes Ureteric Calculi Ureteric calculi are discussed on page 266. The ureter is narrowed anatomically where it bends down into the pelvis at the pelvic brim and where it passes through the bladder wall. It is at these sites that urinary stones may be arrested. When a calculus enters the lower pelvic part of the ureter, the pain is often referred to the testis and the tip of the penis in the male and the labium majus in the female. Palpation of the Urinary Bladder The full bladder in the adult projects up into the abdomen and may be palpated through the anterior abdominal wall above the symphysis pubis. Bimanual palpation of the empty bladder with or without a general anesthetic is an important method of examining the bladder. In the male, one hand is placed on the anterior abdominal wall above the symphysis pubis, and the gloved index finger of the other hand is inserted into the rectum. From their knowledge of anatomy, students can see that the bladder wall can be palpated between the examining fingers. In the female, an abdominovaginal examination can be similarly made. In the child, the bladder is in a higher position than in the adult because of the relatively smaller size of the pelvis. Bladder Distention The normal adult bladder has a capacity of about 500 mL. In the presence of urinary obstruction in males, the bladder may become greatly distended without permanent damage to the bladder wall; in such cases, it is routinely possible to drain 1000 to 1200 mL of urine through a catheter. Urinary Retention In adult males, urinary retention is commonly caused by obstruction to the urethra by a benign or malignant enlargement of the prostate. An acute urethritis or prostatitis can also be responsible. Acute retention occurs much less frequently in females. The only anatomic cause of urinary retention in females is acute inflammation around the urethra (e.g., from herpes). Suprapubic Aspiration As the bladder fills, the superior wall rises out of the pelvis and peels the peritoneum off the posterior surface of the anterior abdominal wall. In cases of acute retention of urine, when catheterization has failed, it is possible to pass a needle into the bladder through the anterior abdominal wall above the symphysis pubis, without entering the peritoneal cavity. This is a simple method of draining off the urine in an emergency. Cystoscopy The mucous membrane of the bladder, the two ureteric orifices, and the urethral meatus can easily be observed by means of a cystoscope. With the bladder distended with fluid, an illuminated tube fitted with lenses is introduced into the bladder through the urethra. Over the trigone, the mucous membrane is pink and smooth. If the bladder is partially emptied, the mucous membrane over the trigone remains smooth, but it is thrown into folds elsewhere. The ureteric orifices are slitlike and eject a drop of urine at intervals of about 1 minute. The interureteric ridge and the uvula vesicae can easily be recognized. Bladder Injuries The bladder may rupture intraperitoneally or extraperitoneally. Intraperitoneal rupture usually involves the superior wall of the bladder and occurs most commonly when the bladder is full and has extended up into the abdomen. Urine and blood escape freely into the peritoneal cavity. Extraperitoneal rupture involves the anterior part of the bladder wall below the level of the peritoneal reflection; it most commonly occurs in fractures of the pelvis when bony fragments pierce the bladder wall. Lower abdominal pain and blood in the urine (hematuria) are found in most patients. In young children, the bladder is an abdominal organ, so abdominal trauma can injure the empty bladder. Difficulty with Micturition After Spinal Cord Injury After injuries to the spinal cord, the nervous control of micturition is disrupted. The normal bladder is innervated as follows:

  • Sympathetic outflow is from the first and second lumbar segments of the spinal cord. The sympathetic nerves (see the footnote on page 350) inhibit contraction of the detrusor muscle of the bladder wall and stimulate closure of the sphincter vesicae.
  • Parasympathetic outflow is from the second, third, and fourth sacral segments of the spinal cord. The parasympathetic nerves stimulate the contraction of the detrusor muscle of the bladder wall and inhibit the action of the sphincter vesicae.
  • Sensory nerve fibers enter the spinal cord at the above segments. The normal process of micturition is described on page 350.

Disruption of the process of micturition by spinal cord injuries may produce the following types of bladder. The atonic bladder occurs during the phase of spinal shock, immediately after the injury, and may last for a few days to several weeks. The bladder wall muscle is relaxed, the sphincter vesicae tightly contracted, and the sphincter urethrae relaxed. The bladder becomes greatly distended and finally overflows. Depending on the level of the cord injury, the patient either is or is not aware that the bladder is full. The automatic reflex bladder (Fig. 7-15) occurs after the patient has recovered from spinal shock, provided that the cord lesion lies above the level of the parasympathetic outflow (S2, 3, and 4). It is the type of bladder normally found in infancy. The bladder fills and empties reflexly. Stretch receptors in the bladder wall are stimulated as the bladder fills, and the afferent impulses pass to the spinal cord (segments S2, 3, and 4). Efferent impulses pass down to the bladder muscle, which contracts; the sphincter vesicae and the urethral sphincter both relax. This simple reflex occurs every 1 to 4 hours. The autonomous bladder (Fig. 7-15) is the condition that occurs if the sacral segments of the spinal cord are destroyed. The sacral segments of the spinal cord are situated in the upper part of the lumbar region of the vertebral column (see page 871). The bladder is without any external reflex control. The bladder wall is flaccid, and the capacity of the bladder is greatly increased. It merely fills to capacity and overflows; continual dribbling is the result. The bladder may be partially emptied by manual compression of the lower part of the anterior abdominal wall, but infection of the urine and back-pressure effects on the ureters and kidneys are inevitable. P.352

Figure 7-14 Nervous control of the bladder. Sympathetic fibers have been omitted for simplification.

Male Genital Organs The testes and epididymides are described on page 169. Vas Deferens The vas deferens is a thick-walled tube about 18 in. (45 cm) long that conveys mature sperm from the epididymis to the ejaculatory duct and the urethra. It arises from the lower end or tail of the epididymis and passes through the inguinal canal. It emerges from the deep inguinal ring and passes around the lateral margin of the inferior epigastric artery (Fig. 7-11). It then passes downward and backward on the lateral wall of the pelvis and crosses the ureter in the region of the ischial spine. The vas deferens then runs medially and downward on the posterior surface of the bladder (Fig. 7-11). The terminal part of the vas deferens is dilated to form the ampulla of the vas deferens. The inferior end of the ampulla narrows down and joins the duct of the seminal vesicle to form the ejaculatory duct. Seminal Vesicles The seminal vesicles are two lobulated organs about 2 in. (5 cm) long lying on the posterior surface of the bladder (Fig. 7-13). On the medial side of each vesicle lies the terminal part of the vas deferens. Posteriorly, the seminal vesicles are related to the rectum (Fig. 7-4). Inferiorly, each seminal vesicle narrows and joins the vas deferens of the same side to form the ejaculatory duct. Each seminal vesicle consists of a much-coiled tube embedded in connective tissue. Blood Supply Arteries The inferior vesicle and middle rectal arteries. P.353

Figure 7-15 A. Nervous control of the bladder after section of the spinal cord in the upper thoracic region. Destruction of the sacral segments of the spinal cord. B. The afferent sensory fibers from the bladder entering the central nervous system and the parasympathetic efferent fibers passing to the bladder are shown; the sympathetic fibers have been omitted for clarity.

Veins The veins drain into the internal iliac veins. Lymph Drainage The internal iliac nodes. Function The function of the seminal vesicles is to produce a secretion that is added to the seminal fluid. The secretions nourish the spermatozoa. During ejaculation the seminal vesicles contract and expel their contents into the ejaculatory ducts, thus washing the spermatozoa out of the urethra. Ejaculatory Ducts The two ejaculatory ducts are each less than 1 in. (2.5 cm) long and are formed by the union of the vas deferens and the duct of the seminal vesicle (Fig. 7-16). The ejaculatory ducts pierce the posterior surface of the prostate and open into the prostatic part of the urethra, close to the margins of the prostatic utricle; their function is to drain the seminal fluid into the prostatic urethra. Prostate Location and Description The prostate is a fibromuscular glandular organ that surrounds the prostatic urethra (Figs. 7-4 and 7-16). It is about 1.25 in. (3 cm) long and lies between the neck of the bladder above and the urogenital diaphragm below (Fig. 7-16). The prostate is surrounded by a fibrous capsule (Fig. 7-16). The somewhat conical prostate has a base, which lies P.354
against the bladder neck above, and an apex, which lies against the urogenital diaphragm below. The two ejaculatory ducts pierce the upper part of the posterior surface of the prostate to open into the prostatic urethra at the lateral margins of the prostatic utricle (Fig. 7-16).

Figure 7-16 Prostate in coronal section (A), sagittal section (B), and horizontal section (C). In the coronal section, note the openings of the ejaculatory ducts on the margin of the prostatic utricle.

Relations

  • Superiorly: The base of the prostate is continuous with the neck of the bladder, the smooth muscle passing without interruption from one organ to the other. The urethra enters the center of the base of the prostate (Fig. 7-4).
  • Inferiorly: The apex of the prostate lies on the upper surface of the urogenital diaphragm. The urethra leaves the prostate just above the apex on the anterior surface (Fig. 7-16).
  • Anteriorly: The prostate is related to the symphysis pubis, separated from it by the extraperitoneal fat in the retropubic space (cave of Retzius). The prostate is connected to the posterior aspect of the pubic bones by the fascial puboprostatic ligaments (Fig. 7-4).
  • Posteriorly: The prostate (Figs. 7-4 and 7-16) is closely related to the anterior surface of the rectal ampulla and is P.355
    separated from it by the rectovesical septum (fascia of Denonvilliers). This septum is formed in fetal life by the fusion of the walls of the lower end of the rectovesical pouch of peritoneum, which originally extended down to the perineal body.
  • Laterally: The prostate is embraced by the anterior fibers of the levator ani as they run posteriorly from the pubis (Fig. 7-16).

Structure of the Prostate The numerous glands of the prostate are embedded in a mixture of smooth muscle and connective tissue, and their ducts open into the prostatic urethra. The prostate is incompletely divided into five lobes (Fig. 7-16). The anterior lobe lies in front of the urethra and is devoid of glandular tissue. The median, or middle, lobe is the wedge of gland situated between the urethra and the ejaculatory ducts. Its upper surface is related to the trigone of the bladder; it is rich in glands. The posterior lobe is situated behind the urethra and below the ejaculatory ducts and also contains glandular tissue. The right and left lateral lobes lie on either side of the urethra and are separated from one another by a shallow vertical groove on the posterior surface of the prostate. The lateral lobes contain many glands. Function of the Prostate The prostate produces a thin, milky fluid containing citric acid and acid phosphatase that is added to the seminal fluid at the time of ejaculation. The smooth muscle, which surrounds the glands, squeezes the secretion into the prostatic urethra. The prostatic secretion is alkaline and helps neutralize the acidity in the vagina. Blood Supply Arteries Branches of the inferior vesical and middle rectal arteries. Veins The veins form the prostatic venous plexus, which lies outside the capsule of the prostate (Fig. 7-16). The prostatic plexus receives the deep dorsal vein of the penis and numerous vesical veins and drains into the internal iliac veins. Lymph Drainage Internal iliac nodes. Nerve Supply Inferior hypogastric plexuses. The sympathetic nerves stimulate the smooth muscle of the prostate during ejaculation. Clinical Notes Prostate Examination The prostate can be examined clinically by palpation by performing a rectal examination (see page 397). The examiner’s gloved finger can feel the posterior surface of the prostate through the anterior rectal wall. Prostate Activity and Disease It is now generally believed that the normal glandular activity of the prostate is controlled by the androgens and estrogens circulating in the bloodstream. The secretions of the prostate are poured into the urethra during ejaculation and are added to the seminal fluid. Acid phosphatase is an important enzyme present in the secretion in large amounts. When the glandular cells producing this enzyme cannot discharge their secretion into the ducts, as in carcinoma of the prostate, the serum acid phosphatase level of the blood rises. It has been shown that trace amounts of proteins produced specifically by prostatic epithelial cells are found in peripheral blood. In certain prostatic diseases, notably cancer of the prostate, this protein appears in the blood in increased amounts. The specific protein level can be measured by a simple laboratory test called the PSA (prostate-specific antigen) test. Benign Enlargement of the Prostate Benign enlargement of the prostate is common in men older than 50 years. The cause is possibly an imbalance in the hormonal control of the gland. The median lobe of the gland enlarges upward and encroaches within the sphincter vesicae, located at the neck of the bladder. The leakage of urine into the prostatic urethra causes an intense reflex desire to micturate. The enlargement of the median and lateral lobes of the gland produces elongation and lateral compression and distortion of the urethra so that the patient experiences difficulty in passing urine and the stream is weak. Back-pressure effects on the ureters and both kidneys are a common complication. The enlargement of the uvula vesicae (owing to the enlarged median lobe) results in the formation of a pouch of stagnant urine behind the urethral orifice within the bladder (Fig. 7-17). The stagnant urine frequently becomes infected, and the inflamed bladder (cystitis) adds to the patient’s symptoms. In all operations on the prostate, the surgeon regards the prostatic venous plexus with respect. The veins have thin walls, are valveless, and are drained by several large trunks directly into the internal iliac veins. Damage to these veins can result in a severe hemorrhage. Prostate Cancer and the Prostatic Venous Plexus Many connections between the prostatic venous plexus and the vertebral veins exist. During coughing and sneezing or abdominal straining, it is possible for prostatic venous blood to flow in a reverse direction and enter the vertebral veins. This explains the frequent occurrence of skeletal metastases in the lower vertebral column and pelvic bones of patients with carcinoma of the prostate. Cancer cells enter the skull via this route by floating up the valveless prostatic and vertebral veins. P.356

Figure 7-17 Sagittal section of a prostate that had undergone benign enlargement of the median lobe. Note the bladder pouch filled with stagnant urine behind the prostate.

Prostatic Urethra The prostatic urethra is about 1.25 in. (3 cm) long and begins at the neck of the bladder. It passes through the prostate from the base to the apex, where it becomes continuous with the membranous part of the urethra (Fig. 7-16). The prostatic urethra is the widest and most dilatable portion of the entire urethra. On the posterior wall is a longitudinal ridge called the urethral crest (Fig. 7-16). On each side of this ridge is a groove called the prostatic sinus; the prostatic glands open into these grooves. On the summit of the urethral crest is a depression, the prostatic utricle, which is an analog of the uterus and vagina in females. On the edge of the mouth of the utricle are the openings of the two ejaculatory ducts (Fig. 7-16). Visceral Pelvic Fascia The visceral pelvic fascia is a layer of connective tissue that covers and supports the pelvic viscera (Fig. 7-16). Peritoneum The peritoneum is best understood by tracing it around the pelvis in a sagittal plane (Fig. 7-4). The peritoneum passes down from the anterior abdominal wall onto the upper surface of the urinary bladder. It then runs down on the posterior surface of the bladder for a short distance until it reaches the upper ends of the seminal vesicles. Here it sweeps backward to reach the anterior aspect of the rectum, forming the shallow rectovesical pouch. The peritoneum then passes up on the front of the middle third of the rectum and the front and lateral surfaces of the upper third of the rectum. It then becomes continuous with the parietal peritoneum on the posterior abdominal wall. It is thus seen that the lowest part of the abdominopelvic peritoneal cavity, when the patient is in the erect position, is the rectovesical pouch (Fig. 7-4). The peritoneum covering the superior surface of the bladder passes laterally to the lateral pelvic walls and does not cover the lateral surfaces of the bladder. It is important to remember that as the bladder fills, the superior wall rises up into the abdomen and peels off the peritoneum from the anterior abdominal wall so that the bladder becomes directly in contact with the abdominal wall. Pelvic Viscera in the Female The rectum, sigmoid colon, and terminal coils of ileum occupy the posterior part of the pelvic cavity (Fig. 7-5), as described previously. The contents of the anterior part of the pelvic cavity in the female are described in the following sections. Ureters The ureter crosses over the pelvic inlet in front of the bifurcation of the common iliac artery (Fig. 7-18). It runs downward and backward in front of the internal iliac artery and behind the ovary until it reaches the region of the ischial spine. It then turns forward and medially beneath the base of the broad ligament, where it is crossed by the uterine artery (Figs. 7-18 and 7-19). The ureter then runs forward, lateral to the lateral fornix of the vagina, to enter the bladder. Urinary Bladder As in the male, the urinary bladder is situated immediately behind the pubic bones (Fig. 7-5). Because of the absence of the prostate, the bladder lies at a lower level than in the male pelvis, and the neck rests directly on the upper surface of the urogenital diaphragm. The close relation of the bladder to the uterus and the vagina is of considerable clinical importance (Fig. 7-5). The apex of the bladder lies behind the symphysis pubis (Fig. 7-5). The base, or posterior surface, is separated by the vagina from the rectum. The superior surface is related to the uterovesical pouch of peritoneum and to the body of the uterus. The inferolateral surfaces are related in front to the retropubic pad of fat and the pubic bones. More posteriorly, they lie in contact with the obturator internus muscle above and the levator ani muscle below. The neck of the bladder rests on the upper surface of the urogenital diaphragm. The general shape and structure of the bladder; its blood supply, lymph drainage, and nerve supply; and the process of micturition are identical to those in the male. P.357
Clinical Notes Stress Incontinence The bladder is normally supported by the visceral pelvic fascia, which in certain areas is condensed to form ligaments. However, the most important support for the bladder is the tone of the levatores ani muscles. In the female, a difficult labor, especially one in which forceps is used, excessively stretches the supports of the bladder neck, and the normal angle between the urethra and the posterior wall of the bladder is lost. This injury causes stress incontinence, a condition of partial urinary incontinence occurring when the patient coughs or strains or laughs excessively. Embryologic Notes Development of the Bladder in Both Sexes The division of the cloaca into anterior and posterior parts by the development of the urorectal septum is described on page 345. The posterior portion forms the anorectal canal (Fig. 7-20). The entrance of the distal ends of the mesonephric ducts into the anterior part of the cloaca on each side permits one, for purposes of description, to divide the anterior part of the cloaca into an area above the duct entrances called the primitive bladder and another area below called the urogenital sinus. The caudal ends of the mesonephric ducts now become absorbed into the lower part of the bladder so that the ureters and ducts have individual openings in the dorsal wall (Fig. 7-20). With differential growth of the dorsal bladder wall, the ureters come to open through the lateral angles of the bladder, and the mesonephric ducts open close together in what will be the urethra. That part of the dorsal bladder wall marked off by the openings of these four ducts forms the trigone of the bladder (Fig. 7-21). Thus, it is seen that in the earliest stages the lining of the bladder over the trigone is mesodermal in origin; later, this mesodermal tissue is thought to be replaced by epithelium of entodermal origin. The smooth muscle of the bladder wall is derived from the splanchnopleuric mesoderm. The primitive bladder may now be divided into an upper dilated portion, the bladder, and a lower narrow portion, the urethra (Fig. 7-20). The apex of the bladder is continuous with the allantois, which now becomes obliterated and forms a fibrous core, the urachus. The urachus persists throughout life as a ligament that runs from the apex of the bladder to the umbilicus and is called the median umbilical ligament. Congenital Anomalies of the Bladder Exstrophy of the Bladder (Ectopia Vesicae) Exstrophy of the bladder occurs three times more commonly in males than in females. The posterior bladder wall protrudes through a defect in the anterior abdominal wall below the umbilicus (Fig. 7-22). The condition is caused by a failure of the embryonic mesenchyme to invade the embryonic disc caudal to the cloacal membrane (Fig. 7-22). The absence of intervening mesenchyme between the ectoderm and entoderm produces an unstable state, which is followed by breakdown of this area. Because of the urinary incontinence and almost certain occurrence of ascending urinary infection, surgical reconstruction of the bladder is attempted. Fate of the Mesonephric Duct in Both Sexes In both sexes, the mesonephric (or Wolffian) duct gives origin on each side to the ureteric bud, which forms the ureter, the pelvis of the ureter, the major and minor calyces, and the collecting tubules of the kidney (see page 267). Its inferior end is absorbed into the developing bladder and forms the trigone and part of the urethra. In the male, its upper or cranial end is joined to the developing testis by the efferent ductules of the testis, and so it becomes the duct of the epididymis, the vas deferens, and the ejaculatory duct. From the latter, a small diverticulum arises that forms the seminal vesicle (see Fig. 4-26). In the female, the mesonephric duct largely disappears. Only small remnants persist—as the duct of the epoophoron and the duct of the paroophoron. The caudal end may persist and extend from the epoophoron to the hymen as Gartner’s duct. Development of the Urethra In the male, the prostatic urethra is formed from two sources. The proximal part, as far as the openings of the ejaculatory ducts, is derived from the mesonephric ducts. The distal part of the prostatic urethra is formed from the urogenital sinus (Fig. 7-21). The membranous urethra and the greater part of the penile urethra also are formed from the urogenital sinus. The distal end of the penile urethra is derived from an ingrowth of ectodermal cells on the glans penis. In the female, the upper two thirds of the urethra are derived from the mesonephric ducts. The lower end of the urethra is formed from the urogenital sinus (Fig. 7-21). P.358

Figure 7-18 Right half of the pelvis showing the ovary, the uterine tube, and the vagina.
Figure 7-19 A. Coronal section of the pelvis showing the uterus, broad ligaments, and right ovary on posterior view. The left ovary and part of the left uterine tube have been removed for clarity. B. Uterus on lateral view. Note the structures that lie within the broad ligament. Note that the uterus has been retroverted into the plane of the vaginal lumen in both diagrams.

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Figure 7-20 Formation of the urinary bladder from the anterior part of the cloaca and the terminal parts of the mesonephric ducts in both sexes. The mesonephric ducts and the ureteric buds are drawn into the developing bladder.

P.360

Figure 7-21 Parts of the bladder and urethra derived from the mesonephric ducts in both sexes (hatch marks). The lower end of the urethra in the female and the lower part of the prostatic urethra in the male are formed from the urogenital sinus.
Figure 7-22 A. Exstrophy of the bladder. B. Dorsal view of the embryonic disc. The normal path taken by the growing embryonic mesenchyme in the region of the cloaca is shown. C. Fetus as seen from the side. The head and tail folds have developed, but the mesenchyme has failed to enter the ventral body wall between the cloaca and the umbilical cord.

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Female Genital Organs Ovary Location and Description Each ovary is oval shaped, measuring 1.5 by 0.75 in. (4 by 2 cm), and is attached to the back of the broad ligament by the mesovarium (Fig. 7-19). That part of the broad ligament extending between the attachment of the mesovarium and the lateral wall of the pelvis is called the suspensory ligament of the ovary (Fig. 7-19). The round ligament of the ovary, which represents the remains of the upper part of the gubernaculum, connects the lateral margin of the uterus to the ovary (Figs. 7-18 and 7-19). The ovary usually lies against the lateral wall of the pelvis in a depression called the ovarian fossa, bounded by the external iliac vessels above and by the internal iliac vessels behind (Fig. 7-18). The position of the ovary is, however, extremely variable, and it is often found hanging down in the rectouterine pouch (pouch of Douglas). During pregnancy, the enlarging uterus pulls the ovary up into the abdominal cavity. After childbirth, when the broad ligament is lax, the ovary takes up a variable position in the pelvis. The ovaries are surrounded by a thin fibrous capsule, the tunica albuginea. This capsule is covered externally by a modified area of peritoneum called the germinal epithelium. The term germinal epithelium is a misnomer because the layer does not give rise to ova. Oogonia develop before birth from primordial germ cells. Before puberty, the ovary is smooth, but after puberty, the ovary becomes progressively scarred as successive corpora lutea degenerate. After menopause, the ovary becomes shrunken and its surface is pitted with scars. Function The ovaries are the organs responsible for the production of the female germ cells, the ova, and the female sex hormones, estrogen and progesterone, in the sexually mature female. Blood Supply Arteries The ovarian artery arises from the abdominal aorta at the level of the first lumbar vertebra. Veins The ovarian vein drains into the inferior vena cava on the right side and into the left renal vein on the left side. Lymph Drainage The lymph vessels of the ovary follow the ovarian artery and drain into the para-aortic nodes at the level of the first lumbar vertebra. Nerve Supply The nerve supply to the ovary is derived from the aortic plexus and accompanies the ovarian artery. The blood supply, lymph drainage, and nerve supply of the ovary pass over the pelvic inlet and cross the external iliac vessels (Fig. 7-19). They reach the ovary by passing through the lateral end of the broad ligament, the part known as the suspensory ligament of the ovary. The vessels and nerves finally enter the hilum of the ovary via the mesovarium. (Compare the blood supply and the lymph drainage of the ovary with those of the testis.) Clinical Notes Position of the Ovary The ovary is kept in position by the broad ligament and the mesovarium. After pregnancy, the broad ligament is lax, and the ovaries may prolapse into the rectouterine pouch (pouch of Douglas). In these circumstances, the ovary may be tender and cause discomfort on sexual intercourse (dyspareunia). An ovary situated in the rectouterine pouch may be palpated through the posterior fornix of the vagina. Cysts of the Ovary Follicular cysts are common and originate in unruptured graafian follicles; they rarely exceed 0.6 in. (1.5 cm) in diameter. Luteal cysts are formed in the corpus luteum. Fluid is retained, and the corpus luteum cannot become fibrosed. Luteal cysts rarely exceed 1.2 in. (3 cm) in diameter. Embryologic Notes Development of the Ovary The female sex chromosome causes the genital ridge on the posterior abdominal wall to secrete estrogens. The presence of estrogen and the absence of testosterone induce the development of the ovary and the other female genital organs. The sex cords contained within the genital ridges contain groups of primordial germ cells. These become broken up into irregular cell clusters by the proliferating mesenchyme (Fig. 7-23). The germ cells differentiate into oogonia, and by the third month, they start to undergo a number of mitotic divisions within the cortex of the ovary to form primary oocytes. These primary oocytes become surrounded by a single layer of cells derived from the sex cords, called the granulosa cells. Thus, primordial follicles have been formed, but later, many degenerate. The mesenchyme that surrounds the follicles provides the ovarian stroma. The relationship of the ovary to the developing uterine tube is shown in Figure 7-24. Ovarian Dysgenesis Complete failure of both ovaries to develop is found in Turner’s syndrome. The classic features of this syndrome are webbed neck, short stocky build, increased carrying angle of the elbows, lack of secondary sex characteristics, and amenorrhea. Imperfect Descent of the Ovary The ovary may fail to descend into the pelvis or very rarely may be drawn downward with the round ligament of the uterus into the inguinal canal or even into the labium majus. P.362

Figure 7-23 Formation of the ovary and its relationship to the mesonephric and paramesonephric ducts.
Figure 7-24 The descent of the ovary and its relationship to the developing uterine tube and uterus.

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Uterine Tube Location and Description The two uterine tubes are each about 4 in. (10 cm) long and lie in the upper border of the broad ligament (Figs. 7-18 and 7-19). Each connects the peritoneal cavity in the region of the ovary with the cavity of the uterus. The uterine tube is divided into four parts:

  • The infundibulum is the funnel-shaped lateral end that projects beyond the broad ligament and overlies the ovary. The free edge of the funnel has several fingerlike processes, known as fimbriae, which are draped over the ovary (Figs. 7-19 and 7-25).
  • The ampulla is the widest part of the tube (Fig. 7-25).
  • The isthmus is the narrowest part of the tube and lies just lateral to the uterus (Fig. 7-25).
  • The intramural part is the segment that pierces the uterine wall (Fig. 7-25).

Function The uterine tube receives the ovum from the ovary and provides a site where fertilization of the ovum can take place (usually in the ampulla). It provides nourishment for the fertilized ovum and transports it to the cavity of the uterus. The tube serves as a conduit along which the spermatozoa travel to reach the ovum.

Figure 7-25 A. Different parts of the uterine tube and the uterus. B. External os of the cervix: (above) nulliparous; (below) parous. C. Anteverted position of the uterus. D. Anteverted and anteflexed position of the uterus.

Blood Supply Arteries The uterine artery from the internal iliac artery and the ovarian artery from the abdominal aorta (Fig. 7-25). Veins The veins correspond to the arteries. Lymph Drainage The internal iliac and para-aortic nodes. Nerve Supply Sympathetic and parasympathetic nerves from the inferior hypogastric plexuses. P.364

Figure 7-26 An ectopic pregnancy located where the ampulla of the uterine tube narrows down to join the isthmus. Note the thin tubal wall compared to the thick decidua that lines the body of the uterus.

Clinical Notes The Uterine Tube as a Conduit for Infection The uterine tube lies in the upper free border of the broad ligament and is a direct route of communication from the vulva through the vagina and uterine cavity to the peritoneal cavity. Pelvic Inflammatory Disease The pathogenic organism(s) enter the body through sexual contact and ascend through the uterus and enter the uterine tubes. Salpingitis may follow, with leakage of pus into the peritoneal cavity, causing pelvic peritonitis. A pelvic abscess usually follows, or the infection spreads farther, causing general peritonitis. Ectopic Pregnancy Implantation and growth of a fertilized ovum may occur outside the uterine cavity in the wall of the uterine tube (Fig. 7-26). This is a variety of ectopic pregnancy. There being no decidua formation in the tube, the eroding action of the trophoblast quickly destroys the wall of the tube. Tubal abortion or rupture of the tube, with the effusion of a large quantity of blood into the peritoneal cavity, is the common result. The blood pours down into the rectouterine pouch (pouch of Douglas) or into the uterovesical pouch. The blood may quickly ascend into the general peritoneal cavity, giving rise to severe abdominal pain, tenderness, and guarding. Irritation of the subdiaphragmatic peritoneum (supplied by phrenic nerves C3, 4, and 5) may give rise to referred pain to the shoulder skin (supraclavicular nerves C3 and 4). Tubal Ligation Ligation and division of the uterine tubes is a method of obtaining permanent birth control and is usually restricted to women who already have children. The ova that are discharged from the ovarian follicles degenerate in the tube proximal to the obstruction. If, later, the woman wishes to have an additional child, restoration of the continuity of the uterine tubes can be attempted, and, in about 20% of women, fertilization occurs. Embryologic Notes Development of the Uterine Tube Early on in development, the paramesonephric ducts appear on the posterior abdominal wall on the lateral side of the mesonephros. The uterine tube on each side is formed from the cranial vertical and middle horizontal parts of the paramesonephric duct (Fig. 7-27). The tube elongates and becomes coiled; differentiation of the muscle and mucous membrane takes place; the fimbriae develop; and the infundibulum, ampulla, and isthmus are identifiable. Uterus Location and Description The uterus is a hollow, pear-shaped organ with thick muscular walls. In the young nulliparous adult, it measures 3 in. (8 cm) long, 2 in. (5 cm) wide, and 1 in. (2.5 cm) thick. It is divided into the fundus, body, and cervix (Fig. 7-25). The fundus is the part of the uterus that lies above the entrance of the uterine tubes. The body is the part of the uterus that lies below the entrance of the uterine tubes. The cervix is the narrow part of the uterus. It pierces the anterior wall of the vagina and is divided into the supravaginal and vaginal parts of the cervix. P.365

Figure 7-27 The relationship of the mesonephric and paramesonephric ducts to the developing ovary. A. Cross section of a developing ovary. B. Anterior view of ovaries and ducts. C and D. Mesonephric and paramesonephric ducts in a cross section of the pelvis. Note the developing broad ligament.

The cavity of the uterine body is triangular in coronal section, but it is merely a cleft in the sagittal plane (Fig. 7-25). The cavity of the cervix, the cervical canal, communicates with the cavity of the body through the internal os and with that of the vagina through the external os. Before the birth of the first child, the external os is circular. In a parous woman, the vaginal part of the cervix is larger, and the external os becomes a transverse slit so that it possesses an anterior lip and a posterior lip (Fig. 7-25). Relations

  • Anteriorly: The body of the uterus is related anteriorly to the uterovesical pouch and the superior surface of the bladder (Fig. 7-5). The supravaginal cervix is related to the superior surface of the bladder. The vaginal cervix is related to the anterior fornix of the vagina.
  • Posteriorly: The body of the uterus is related posteriorly to the rectouterine pouch (pouch of Douglas) with coils of ileum or sigmoid colon within it (Fig. 7-5).
  • Laterally: The body of the uterus is related laterally to the broad ligament and the uterine artery and vein (Fig. 7-19). The supravaginal cervix is related to the ureter as it passes forward to enter the bladder. The vaginal cervix is related to the lateral fornix of the vagina. The uterine tubes enter the superolateral angles of the uterus, and the round ligaments of the ovary and of the uterus are attached to the uterine wall just below this level.

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Function The uterus serves as a site for the reception, retention, and nutrition of the fertilized ovum. Positions of the Uterus In most women, the long axis of the uterus is bent forward on the long axis of the vagina. This position is referred to as anteversion of the uterus (Fig. 7-25). Furthermore, the long axis of the body of the uterus is bent forward at the level of the internal os with the long axis of the cervix. This position is termed anteflexion of the uterus (Fig. 7-25). Thus, in the erect position and with the bladder empty, the uterus lies in an almost horizontal plane. In some women, the fundus and body of the uterus are bent backward on the vagina so that they lie in the rectouterine pouch (pouch of Douglas). In this situation, the uterus is said to be retroverted. If the body of the uterus is, in addition, bent backward on the cervix, it is said to be retroflexed. Structure of the Uterus The uterus is covered with peritoneum except anteriorly, below the level of the internal os, where the peritoneum passes forward onto the bladder. Laterally, there is also a space between the attachment of the layers of the broad ligament. The muscular wall, or myometrium, is thick and made up of smooth muscle supported by connective tissue. The mucous membrane lining the body of the uterus is known as the endometrium. It is continuous above with the mucous membrane lining the uterine tubes and below with the mucous membrane lining the cervix. The endometrium is applied directly to the muscle, there being no submucosa. From puberty to menopause, the endometrium undergoes extensive changes during the menstrual cycle in response to the ovarian hormones.

Figure 7-28 Coronal section of the pelvis showing relation of the levatores ani muscles and transverse cervical ligaments to the uterus and vagina. Note that the transverse cervical ligaments are formed from a condensation of visceral pelvic fascia.

The supravaginal part of the cervix is surrounded by visceral pelvic fascia, which is referred to as the parametrium. It is in this fascia that the uterine artery crosses the ureter on each side of the cervix. Blood Supply Arteries The arterial supply to the uterus is mainly from the uterine artery, a branch of the internal iliac artery. It reaches the uterus by running medially in the base of the broad ligament (Fig. 7-19). It crosses above the ureter at right angles and reaches the cervix at the level of the internal os (Fig. 7-25). The artery then ascends along the lateral margin of the uterus within the broad ligament and ends by anastomosing with the ovarian artery, which also assists in supplying the uterus. The uterine artery gives off a small descending branch that supplies the cervix and the vagina. Veins The uterine vein follows the artery and drains into the internal iliac vein. Lymph Drainage The lymph vessels from the fundus of the uterus accompany the ovarian artery and drain into the para-aortic nodes at the level of the first lumbar vertebra. The vessels from the body and cervix drain into the internal and external iliac lymph nodes. A few lymph vessels follow the round ligament of the uterus through the inguinal canal and drain into the superficial inguinal lymph nodes. P.367
Nerve Supply Sympathetic and parasympathetic nerves from branches of the inferior hypogastric plexuses Supports of the Uterus The uterus is supported mainly by the tone of the levatores ani muscles and the condensations of pelvic fascia, which form three important ligaments. The Levatores Ani Muscles and the Perineal Body The origin and the insertion of the levatores ani muscles are described in Chapter 6. They form a broad muscular sheet stretching across the pelvic cavity, and, together with the pelvic fascia on their upper surface, they effectively support the pelvic viscera and resist the intra-abdominal pressure transmitted downward through the pelvis. The medial edges of the anterior parts of the levatores ani muscles are attached to the cervix of the uterus by the pelvic fascia (Fig. 7-28).

Figure 7-29 Ligamentous supports of uterus. A. As seen from below. B. Lateral view. These ligaments are formed from visceral pelvic fascia.

Some of the fibers of levator ani are inserted into a fibromuscular structure called the perineal body (Fig. 7-5). This structure is important in maintaining the integrity of the pelvic floor; if the perineal body is damaged during childbirth, prolapse of the pelvic viscera may occur. The perineal body lies in the perineum between the vagina and the anal canal. It is slung up to the pelvic walls by the levatores ani and thus supports the vagina and, indirectly, the uterus. The Transverse Cervical, Pubocervical, and Sacrocervical Ligaments These three ligaments are subperitoneal condensations of pelvic fascia on the upper surface of the levatores ani muscles. They are attached to the cervix and the vault of the vagina and play an important part in supporting the uterus and keeping the cervix in its correct position (Figs. 7-28 and 7-29). P.368
Transverse Cervical (Cardinal) Ligaments Transverse cervical ligaments are fibromuscular condensations of pelvic fascia that pass to the cervix and the upper end of the vagina from the lateral walls of the pelvis. Pubocervical Ligaments The pubocervical ligaments consist of two firm bands of connective tissue that pass to the cervix from the posterior surface of the pubis. They are positioned on either side of the neck of the bladder, to which they give some support (pubovesical ligaments). Sacrocervical Ligaments The sacrocervical ligaments consist of two firm fibromuscular bands of pelvic fascia that pass to the cervix and the upper end of the vagina from the lower end of the sacrum. They form two ridges, one on either side of the rectouterine pouch (pouch of Douglas). The broad ligaments and the round ligaments of the uterus are lax structures, and the uterus can be pulled up or pushed down for a considerable distance before they become taut. Clinically, they are considered to play a minor role in supporting the uterus. The round ligament of the uterus, which represents the remains of the lower half of the gubernaculum, extends between the superolateral angle of the uterus, through the deep inguinal ring and inguinal canal, to the subcutaneous tissue of the labium majus (Fig. 7-18). It helps keep the uterus anteverted (tilted forward) and anteflexed (bent forward) but is considerably stretched during pregnancy. Uterus in the Child The fundus and body of the uterus remain small until puberty, when they enlarge greatly in response to the estrogens secreted by the ovaries. Uterus After Menopause After menopause, the uterus atrophies and becomes smaller and less vascular. These changes occur because the ovaries no longer produce estrogens and progesterone. Uterus in Pregnancy During pregnancy, the uterus becomes greatly enlarged as a result of the increasing production of estrogens and progesterone, first by the corpus luteum of the ovary and later by the placenta. At first it remains as a pelvic organ, but by the third month the fundus rises out of the pelvis, and by the ninth month it has reached the xiphoid process. The increase in size is largely a result of hypertrophy of the smooth muscle fibers of the myometrium, although some hyperplasia takes place. Role of the Uterus in Labor Labor, or parturition, is the series of processes by which the baby, the fetal membranes, and the placenta are expelled from the genital tract of the mother. Normally this process takes place at the end of the 10th lunar month, at which time the pregnancy is said to be at term. The cause of the onset of labor is not definitely known. By the end of pregnancy, the contractility of the uterus has been fully developed in response to estrogen, and it is particularly sensitive to the actions of oxytocin at this time. It is possible that the onset of labor is triggered by the sudden withdrawal of progesterone. Once the presenting part (usually the fetal head) starts to stretch the cervix, it is thought that a nervous reflex mechanism is initiated and increases the force of the contractions of the uterine body. The uterine muscular activity is largely independent of the extrinsic innervation. In women in labor, spinal anesthesia does not interfere with the normal uterine contractions. Severe emotional disturbance, however, can cause premature parturition. Clinical Notes Bimanual Pelvic Examination of the Uterus A great deal of useful clinical information can be obtained about the state of the uterus, uterine tubes, and ovaries from a bimanual examination. The examination is easiest in parous women who are able to relax while the examination is in progress. In patients in whom it causes distress, the examination may be performed under an anesthetic. With the bladder empty, the vaginal portion of the cervix is first palpated with the index finger of the right hand. The external os is circular in the nulliparous woman but has anterior and posterior lips in the multiparous woman. The cervix normally has the consistency of the end of the nose, but in the pregnant uterus it is soft and vascular and has the consistency of the lips. The left hand is then placed gently on the anterior abdominal wall above the symphysis pubis, and the fundus and body of the uterus may be palpated between the abdominal and vaginal fingers situated in the anterior fornix. The size, shape, and mobility of the uterus can then be ascertained. In most women, the uterus is anteverted and anteflexed. A retroverted, retroflexed uterus can be palpated through the posterior vaginal fornix. Varicosed Veins and Hemorrhoids in Pregnancy Varicosed veins and hemorrhoids are common conditions in pregnancy. The following factors probably contribute to their cause: pressure of the gravid uterus on the inferior vena cava and the inferior mesenteric vein, impairing venous return, and increased progesterone levels in the blood, leading to relaxation of the smooth muscle in the walls of the veins and venous dilatation. The Anatomy of Emergency Cesarean Section An emergency cesarean section is rarely performed. However, a physician may need to perform this surgery in cases in which the mother may die after suffering a severe traumatic incident. Following maternal death, placental circulation ceases, and the child must be delivered within 10 minutes; after a delay of more than 20 minutes, neonatal survival is rare. The Anatomy of the Technique

  • The bladder is emptied, and an indwelling catheter is left in position. This allows the empty bladder to sink down away from the operating field.
  • A midline skin incision is made that extends from just below the umbilicus to just above the symphysis pubis. The following structures are then incised: superficial fascia, fatty layer, and the membranous layer; deep fascia (thin layer); linear alba; fascia transversalis; extraperitoneal fatty layer; and parietal peritoneum. To avoid damaging loops of the small intestine or the greater omentum, which might be lying beneath the parietal peritoneum, a fold of peritoneum is raised between two hemostats; an incision is then made between the hemostats.
  • The bladder is identified, and a cut is made in the floor of the uterovesical pouch. The bladder is then separated from the lower part of the body of the uterus and depressed downward into the pelvis.
  • The uterus is palpated to identify the presenting part of the fetus.
  • A transverse incision about 1 in. (2.5 cm) long is made into the exposed lower segment of the body of the uterus. Care is taken that the uterine wall is not immediately penetrated and the fetus injured.
  • When the uterine cavity is entered, the amniotic cavity is opened, and amniotic fluid spurts. The uterine incision is then enlarged sufficiently to deliver the head and trunk of the fetus. When possible, the large tributaries and branches of the uterine vessels in the myometrial wall are avoided. Great care has to be taken to avoid the large uterine arteries that course along the lateral margin of the uterus.
  • Once the fetus is delivered, the umbilical cord is clamped and divided.
  • The contracting uterus will cause the placenta to bulge through the uterine incision. The placenta and fetal membranes are then delivered.
  • The uterine incision is closed with a full-thickness continuous suture. The peritoneum over the bladder and lower part of the uterine body is then repaired to restore the integrity of the uterovesical pouch. Finally, the abdominal wall incision is closed in layers.

Prolapse of the Uterus The great importance of the tone of the levatores ani muscles in supporting the uterus has already been emphasized. The importance of the transverse cervical, pubocervical, and sacrocervical ligaments in positioning the cervix within the pelvic cavity has been considered. Damage to these structures during childbirth or general poor body muscular tone may result in downward displacement of the uterus called uterine prolapse. It most commonly reveals itself after menopause, when the visceral pelvic fascia tends to atrophy along with the pelvic organs. In advanced cases, the cervix descends the length of the vagina and may protrude through the orifice. Because of the attachment of the cervix to the vaginal vault, it follows that prolapse of the uterus is always accompanied by some prolapse of the vagina. Hysterectomy and Damage to the Ureter During the surgical procedure of hysterectomy, great care must be exercised to not damage the ureters. When the surgeon is looking for the uterine artery on each side at the base of the broad ligament, it is essential that he or she first identifies the ureter before clamping and tying off the artery. The uterine artery passes forward from the internal iliac artery and crosses the ureter at right angles to reach the cervix at the level of the internal os. Sonography of the Female Pelvis A sonogram of the female pelvis can be used to visualize the uterus and the developing fetus and the vagina (Figs. 7-30, 7-31, and 7-32). P.369

Figure 7-30 Longitudinal sonogram of the female pelvis showing the uterus, the vagina, and the bladder. (Courtesy of M.C. Hill.)

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Figure 7-31 Transverse sonogram of the pelvis in a woman after an automobile accident, in which the liver was lacerated and blood escaped into the peritoneal cavity. The bladder (BL), the body of the uterus (U), and the broad ligaments (white arrows) are identified. Note the presence of blood (dark areas) in the uterovesical pouch (UVP) and the pouch of Douglas (PD). (Courtesy of L. Scoutt.)
Figure 7-32 Longitudinal sonogram of a pregnant uterus at 11 weeks showing the intrauterine gestational sac (black arrowheads) and the amniotic cavity (AC) filled with amniotic fluid; the fetus is seen in longitudinal section with the head (H) and coccyx (C) well displayed. The myometrium (MY) of the uterus can be identified. (Courtesy of L. Scoutt.)

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Embryologic Notes Development of the Uterus The uterus is derived from the fused caudal vertical parts of the paramesonephric ducts (Fig. 7-33), and the site of their angular junction becomes a convex dome and forms the fundus of the uterus. The fusion between the ducts is incomplete at first, a septum persisting between the lumina. Later, the septum disappears so that a single cavity remains. The upper part of the cavity forms the lumen of the body and cervix of the uterus. The myometrium is formed from the surrounding mesenchyme. Agenesis of the Uterus Rarely the uterus will be absent as the result of a failure of the paramesonephric ducts to develop. Infantile Uterus Some adults may have an infantile uterus, a condition in which the uterus is much smaller than normal and resembles that present before puberty. Amenorrhea is present, but the vagina and ovaries may be normal. Failure of Fusion of the Paramesonephric Ducts Failure of the paramesonephric ducts to fuse may cause a variety of uterine defects: (a) The uterus may be duplicated with two bodies and two cervices. (b) There may be a complete septum through the uterus, making two uterine cavities and two cervices. (c) There may be two separate uterine bodies with one cervix. (d) One paramesonephric duct may fail to develop, leaving one uterine tube and half of the body of the uterus. Clinically, the main problems with a double uterus may be seen when pregnancy occurs. Abortion is frequent, and the nonpregnant half of the uterus may cause obstruction at labor. P.372

Figure 7-33 Formation of the uterine tubes, the uterus, and the vagina.

Embryologic Notes Brief Summary of the Implantation of the Fertilized Ovum in the Uterus The blastocyst enters the uterine cavity between the fourth and ninth days after ovulation. Normal implantation takes place in the endometrium of the body of the uterus, most frequently on the upper part of the posterior wall near the midline (Fig. 7-34). As the result of the enzymatic digestion of the uterine epithelium by the trophoblast of the embryo, the blastocyst sinks beneath the surface epithelium and becomes embedded in the stroma by the 11th or 12th day. Embryologic Notes A Summary of the Formation of the Placenta The placenta is the organ that carries out respiration, excretion, and nutrition for the embryo, and it is fully formed during the fourth month. The formation of the placenta is complicated and is essentially the development of an organ by mother and child in symbiosis and consists of fetal and maternal parts. The fetal part develops as follows. The trophoblast becomes a highly developed structure, with villi that continue to erode and penetrate deeper into the endometrium. Large irregular spaces known as lacunae appear, which become filled with maternal blood. At the center of each villus is connective tissue containing fetal blood vessels that will eventually anastomose with one another and converge to form the umbilical cord (Fig. 7-35). The maternal part develops as follows. Under the influence of progesterone, secreted first by the corpus luteum and later by the placenta itself, the endometrium becomes greatly thickened and is known as the decidua. Large areas of the decidua become excavated by the invading trophoblastic villi to form the intervillous spaces. The maternal blood vessels open into the spaces so that the outer surfaces of the villi of the fetal part of the placenta become bathed in oxygenated blood (Fig. 7-35). By the fourth month of pregnancy, the placenta is a well- developed organ. As the pregnancy continues, the placenta increases in area and thickness. The placental attachment occupies one third of the internal surface of the uterus. At birth, a few minutes after the delivery of the child, the placenta separates from the uterine wall and is expelled from the uterine cavity as the result of the contractions of the uterine musculature. The line of separation occurs through the spongy layer of the decidua (Fig. 7-35). Gross Appearance of the Placenta at Birth At full term, the placenta has a spongelike consistency. It is flattened and circular, with a diameter of about 8 in. (20 cm) and a thickness of about 1 in. (2.5 cm), and weighs about 1 lb (500 g). It thins out at the edges, where it is continuous with the fetal membranes (Fig. 7-36). The outer, or maternal, surface of a freshly shed placenta is rough on palpation, is dark red, and oozes blood from the torn maternal blood vessels. The inner, or fetal, surface is smooth and shiny and is raised in ridges by the umbilical blood vessels, which radiate from the attachment of the umbilical cord near its center. The fetal membranes (see Fig. 4-36), which surround and enclose the amniotic fluid, are continuous with the edge of the placenta. They are the amnion, the chorion, and a small amount of the adherent maternal decidua. The Placenta and Bleeding in Late Pregnancy The common causes of substantial vaginal bleeding in the third trimester are placenta previa and placental abruption. Placenta Previa Placenta previa occurs in about 1 of every 200 pregnancies. It is more common in multiparous women and in those who have had surgery on the lower part of the uterus. Normally, the placenta is situated in the upper half of the uterus. Should implantation occur in the lower half of the body of the uterus, the condition is called placenta previa. Three types of placenta previa may be recognized: a central placenta previa, in which the entire internal os is covered by placental tissue; marginal placenta previa, when the edge of the placenta is encroaching on the internal os; and a low-lying placenta previa, when the placenta lies low down in the uterus, lateral to the internal os. Severe, painless hemorrhage occurring from the 28th week onward is the clinical sign of placenta previa and is caused by expansion of the lower half of the uterine wall at this time and by its tearing away from the placenta. Placental Abruption Placental abruption is the premature separation of the placenta in which normal implantation has occurred. It occurs in about 1% of pregnancies. It is more common in multiparous women and in women with hypertension in pregnancy. As the placenta separates, hemorrhage occurs; the blood clot dissects the fetal membranes away from the uterine wall. The blood usually escapes through the cervix or ruptures into the amniotic cavity. The blood irritates the myometrium, and uterine muscle tone is increased, which results in contractions. The placental circulation is compromised by the placental separation and the increased pressure on the placenta by the increased uterine tone. Vagina Location and Description The vagina is a muscular tube that extends upward and backward from the vulva to the uterus (Fig. 7-5). It measures about 3 in. (8 cm) long and has anterior and posterior walls, which are normally in apposition. At its upper end, the anterior wall is pierced by the cervix, which projects downward and backward into the vagina. It is important to remember that the upper half of the vagina lies above the pelvic floor and the lower half lies within the perineum (Figs. 7-5 and 7-28). The area of the vaginal lumen, which surrounds the cervix, is divided into four regions, or fornices: anterior, posterior, right lateral, and left lateral. The vaginal orifice in a virgin possesses a thin mucosal fold called the hymen, which is perforated at its center. After childbirth the hymen usually consists only of tags. P.373

Figure 7-34 Sagittal section of the uterus showing the developing conceptus expanding into the uterine cavity. The three different regions of the decidua can be recognized. By the 16th week, the uterine cavity is obliterated by the fusion of the decidua capsularis with the decidua parietalis.

Relations

  • Anteriorly: The vagina is closely related to the bladder above and to the urethra below (Fig. 7-5).
  • Posteriorly: The upper third of the vagina is related to the rectouterine pouch (pouch of Douglas) and its middle third to the ampulla of the rectum. The lower third is related to the perineal body, which separates it from the anal canal (Fig. 7-5).
  • Laterally: In its upper part, the vagina is related to the ureter; its middle part is related to the anterior fibers of the levator ani, as they run backward to reach the perineal body and hook around the anorectal junction (Figs. 7-19 and 7-28). Contraction of the fibers of levator ani compresses the walls of the vagina together. In its lower part, the vagina is related to the urogenital diaphragm (see Chapter 8) and the bulb of the vestibule.

Function The vagina not only is the female genital canal, but it also serves as the excretory duct for the menstrual flow and forms part of the birth canal. Blood Supply Arteries The vaginal artery, a branch of the internal iliac artery, and the vaginal branch of the uterine artery supply the vagina. Veins The vaginal veins form a plexus around the vagina that drains into the internal iliac vein. Lymph Drainage The upper third of the vagina drains to the external and internal iliac nodes, the middle third drains to the internal iliac nodes, and the lower third drains to the superficial inguinal nodes. Nerve Supply The inferior hypogastric plexuses. Supports of the Vagina The upper part of the vagina is supported by the levatores ani muscles and the transverse cervical, pubocervical, and sacrocervical ligaments. These structures are attached to the vaginal wall by pelvic fascia (Figs. 7-28 and 7-29). The middle part of the vagina is supported by the urogenital diaphragm (see Chapter 8). The lower part of the vagina, especially the posterior wall, is supported by the perineal body (Fig. 7-5). Clinical Notes Vaginal Examination The anatomic relations of the vagina are of great clinical importance. Many pathologic conditions occurring in the female pelvis may be diagnosed using a simple vaginal examination. The following structures can be palpated through the vaginal walls from above downward:

  • Anteriorly: The bladder and the urethra
  • Posteriorly: Loops of ileum and the sigmoid colon in the rectouterine peritoneal pouch (pouch of Douglas), the rectal ampulla, and the perineal body
  • Laterally: The ureters, the pelvic fascia and the anterior fibers of the levatores ani muscles, and the urogenital diaphragm

Prolapse of the Vagina The vaginal vault is supported by the same structures that support the uterine cervix. Prolapse of the uterus is necessarily associated with some degree of sagging of the vaginal walls. However, if the supports of the bladder, urethra, or anterior rectal wall are damaged in childbirth, prolapse of the vaginal walls occurs, with the uterus remaining in its correct position.

Figure 7-35 A section through the placenta showing the maternal (top) and fetal (bottom) parts. Note that the maternal part is divided into the basal layer, the spongy layer, and the compact layer. The heavy solid line in the spongy layer indicates where separation occurs between the maternal and fetal parts of the placenta during the third stage of labor.
Figure 7-36 The mature placenta as seen from the fetal surface (A) and from the maternal surface (B).

Sagging of the bladder results in the bulging of the anterior wall of the vagina, a condition known as a cystocele. When the ampulla of the rectum sags against the posterior vaginal wall, the bulge is called a rectocele. Culdocentesis The closeness of the peritoneal cavity to the posterior vaginal fornix enables the physician to drain a pelvic abscess through the vagina without performing a major operation. It is also possible to identify blood or pus in the peritoneal cavity by the passage of a needle through the posterior fornix. Anatomic Structures Through Which the Needle Passes The needle passes through the mucous membrane of the vagina, muscular coat of the vagina, connective tissue coat of the vagina, visceral layer of pelvic fascia, and visceral layer of peritoneum. Anatomic Features of the Complications of Culdocentesis Complications are as follows: (a) The loops of ileum and the sigmoid colon, structures that are normally present within the pouch of Douglas, could be impaled by the needle. However, the presence of blood or pus within the pouch tends to deflect the viscera superiorly. (b) Occasionally, when the uterus is somewhat retroflexed, the needle may enter the posterior wall of the body of the uterus. Vaginal Trauma Coital injury, picket fence–type of impalement injury, and vaginal perforation caused by water under pressure, as occurs in water skiing, are common injuries. Lacerations of the vaginal wall involving the posterior fornix may violate the pouch of Douglas of the peritoneal cavity and cause prolapse of the small intestine into the vagina. Embryologic Notes Development of the Vagina The vagina is developed from the wall of the urogenital sinus (Fig. 7-33). The fused lower ends of the paramesonephric ducts form the body and cervix of the uterus, and once the solid end of the fused ducts reaches the posterior wall of the urogenital sinus, two outgrowths occur from the sinus, called the sinovaginal bulbs. The cells of the sinovaginal bulbs proliferate rapidly and form the vaginal plate. The vaginal plate thickens and elongates and extends around the solid end of the fused paramesonephric ducts. Later, the plate is completely canalized and the vaginal fornices are formed. Vaginal Agenesis If the paramesonephric ducts fail to develop, the wall of the urogenital sinus will fail to form the vaginal plate. In these patients, there is an absence of the vagina, uterus, and uterine tubes. Plastic surgical construction of a vagina should be attempted. Double Vagina A double vagina is caused by incomplete canalization of the vaginal plate. Imperforate Vagina and Imperforate Hymen Imperforate vagina is caused by a failure of the cells to degenerate in the center of the vaginal plates. Imperforate hymen is caused by a failure of the cells of the lower part of the vaginal plate and wall of the urogenital sinus to degenerate. These conditions lead to retention of the menstrual flow, a clinical condition called hematocolpos. Surgical incision of the obstruction, followed by dilatation, relieves the condition. P.374
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Visceral Pelvic Fascia The visceral pelvic fascia is a layer of connective tissue, which, as in the male, covers and supports the pelvic viscera. It is condensed to form the pubocervical, transverse cervical, and sacrocervical ligaments of the uterus. (Fig. 7-29). Clinical Notes Visceral Pelvic Fascia and Infection Clinically, the pelvic fascia in the region of the uterine cervix is often referred to as the parametrium. It is a common site for the spread of acute infections from the uterus and vagina, and here the infection often becomes chronic (pelvic inflammatory disease). Peritoneum The peritoneum in the female, as in the male, is best understood by tracing it around the pelvis in a sagittal plane (Fig. 7-5). The peritoneum passes down from the anterior abdominal wall onto the upper surface of the urinary bladder. It then runs directly onto the anterior surface of the uterus, at the level of the internal os. The peritoneum now passes upward over the anterior surface of the body and fundus of the uterus and then downward over the posterior surface. It continues downward and covers the upper part of the posterior surface of the vagina, where it forms the anterior wall of the rectouterine pouch (pouch of Douglas). The peritoneum then passes onto the front of the rectum, as in the male. In the female, the lowest part of the abdominopelvic peritoneal cavity in the erect position is the rectouterine pouch. Clinical Notes The Rectouterine Pouch and Disease Since the rectouterine pouch (pouch of Douglas) is the most dependent part of the entire peritoneal cavity (when the patient is in the standing position), it frequently becomes the site for the accumulation of blood (from a ruptured ectopic pregnancy) or pus (from a ruptured pelvic appendicitis or in gonococcal peritonitis). Because the pouch lies directly behind the posterior fornix of the vagina, it is commonly violated by misguided nonsterile instruments, which pierce the wall of the posterior fornix in a failed attempt at an illegal abortion. Pelvic peritonitis, often with fatal consequences, is the almost certain result. A needle may be passed into the pouch through the posterior fornix in the procedure known as culdocentesis (see page 375). Surgically, the pouch may be entered in posterior colpotomy. The interior of the female pelvic peritoneal cavity may be viewed for evidence of disease through an endoscope; the instrument is introduced through a small colpotomy incision. P.377
Broad Ligaments The broad ligaments are two-layered folds of peritoneum that extend across the pelvic cavity from the lateral margins of the uterus to the lateral pelvic walls (Fig. 7-19). Superiorly, the two layers are continuous and form the upper free edge. Inferiorly, at the base of the ligament, the layers separate to cover the pelvic floor. The ovary is attached to the posterior layer by the mesovarium. The part of the broad ligament that lies lateral to the attachment of the mesovarium forms the suspensory ligament of the ovary. The part of the broad ligament between the uterine tube and the mesovarium is called the mesosalpinx. At the base of the broad ligament, the uterine artery crosses the ureter (Figs. 7-19 and 7-28). Each broad ligament contains the following:

  • The uterine tube in its upper free border
  • The round ligament of the ovary and the round ligament of the uterus. They represent the remains of the gubernaculum.
  • The uterine and ovarian blood vessels, lymph vessels, and nerves
  • The epoophoron, a vestigial structure that lies in the broad ligament above the attachment of the mesovarium. It represents the remains of the mesonephros (Fig. 7-19).
  • The paroophoron, also a vestigial structure that lies in the broad ligament just lateral to the uterus. It is a mesonephric remnant (Fig. 7-19).

Cross-Sectional Anatomy of the Pelvis To assist in the interpretation of CT scans of the pelvis, students should study the labeled cross sections of the pelvis shown in Figures 7-37 and 7-38.

Figure 7-37 A. Cross section of the male pelvis as seen from above. B. Cross section of the female pelvis as seen from below.

Radiographic Anatomy Radiographic Appearances of the Bony Pelvis A routine anteroposterior view of the pelvis is taken with the patient in the supine position and with the cassette underneath the tabletop. A somewhat distorted view of the lower part of the sacrum and coccyx is obtained, and these bones may be partially obscured by the symphysis pubis. A better view of the sacrum and coccyx can be obtained by slightly tilting the x-ray tube. An anteroposterior radiograph should be systematically examined (Figs. 7-39 through 7-42). The lower lumbar vertebrae, sacrum, and coccyx may be looked at first, followed by the sacroiliac joints, the different parts of the hip bones, and finally the hip joints and the upper ends of the femurs. Gas and fecal material may be seen in the large bowel, and soft tissue shadows of the skin and subcutaneous tissues may also be visualized. To demonstrate the sacrum and sacroiliac joints more clearly, lateral and oblique views of the pelvis are often taken. Radiographic Appearances of the Sigmoid Colon and Rectum Barium Enema The pelvic colon and rectum can be demonstrated by the administration of 2 to 3 pints (1 L) of barium sulfate emulsion slowly through the anus. The appearances of the pelvic colon are similar to those seen in the more proximal parts of the colon, but a distended sigmoid colon usually shows no sacculations. The rectum is seen to have a wider caliber than the colon. P.378

Figure 7-38 Computed tomography scan of the pelvis after a barium meal and intravenous pyelography. Note the presence of the radiopaque material in the small intestine and the right ureter. The section is viewed from below.

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Figure 7-39 Anteroposterior radiograph of the male pelvis.
Figure 7-40 Representation of the radiograph of the pelvis seen in Figure 7-39.

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Figure 7-41 Anteroposterior radiograph of the adult female pelvis.
Figure 7-42 Representation of the radiograph of the pelvis seen in Figure 7-41.

A contrast enema is sometimes useful for examining the mucous membrane of the sigmoid colon. The barium enema is partly evacuated and air is injected into the colon. By this means the walls of the colon become outlined (see Fig. 5-90). P.381
Radiographic Appearances of the Female Genital Tract The instillation of viscous iodine preparations through the external os of the uterus allows the lumen of the cervical canal, the uterine cavity, and the different parts of the uterine tubes to be visualized (Fig. 7-43). This procedure is known as hysterosalpingography. The patency of these structures is demonstrated by the entrance into the peritoneal cavity of some of the opaque medium.

Figure 7-43 Anteroposterior radiograph of the female pelvis after injection of radiopaque compound into the uterine cavity (hysterosalpingogram).

A sonogram of the female pelvis shows the uterus and the vagina (Figs. 7-30, 7-31, and 7-32). Surface Anatomy The surface anatomy of the pelvic viscera is considered on page 330. P.382
Clinical Problem Solving Study the following case histories and select the best answers to the questions following them. A 30-year-old man involved in a barroom brawl was seen in the emergency department. He was found to have a blood-stained tear on the seat of his trousers and lacerations of the anal margin. During the fight he was knocked down and fell in the sitting position on the leg of an upturned bar stool. While under observation he developed the signs and symptoms of peritonitis. 1. The signs and symptoms displayed by this patient could be explained by the following anatomic statements except which? (a) The patient had impaled his rectum on the leg of the upturned bar stool. (b) At operation, a laceration of the anterior wall of the middle of the rectum was found. (c) The leg of the bar stool had entered the rectovesical pouch. (d) The rectal contents had contaminated the peritoneal cavity and were responsible for the development of peritonitis. (e) The anterior surface of the middle third of the rectum has no peritoneal covering. View Answer1. E. The upper third of the rectum has peritoneum on its anterior and lateral surfaces; the middle third has peritoneum on its anterior surface; and the lower third has no peritoneal covering. A 46-year-old man had been treating himself for hemorrhoids for the past 3 years. He had noticed that his feces was often slightly blood stained. For the past 12 months, he had noticed that when he had his bowels open, he always felt that more was to come. Sometimes he went to the toilet several times a day but was only able to pass flatus and blood-stained mucus. Recently, pain had developed down the outside of his right leg. Digital examination of the rectum revealed a large, hard-based ulcer on the posterior wall of the rectum with extensive induration of the pararectal tissues. A diagnosis of advanced carcinoma of the rectum was made. 2. The following statements about this patient are probably correct except which? (a) Some of the bleeding was from the carcinomatous ulcer of the rectum as well as from the hemorrhoids. (b) The lymphatic drainage of the rectum takes place first into the pararectal lymph nodes. (c) Carcinoma of the rectum never metastasizes to the liver. (d) Examination of the right leg revealed some weakness of the muscles supplied by the sciatic nerve. (e) The carcinoma had extended posteriorly to involve the sacral plexus. (f) The patient indicated that the leg pain was felt in skin areas supplied by branches of the sciatic nerve. View Answer2. C. Advanced carcinoma of the rectum not only extends to the pararectal and inferior mesenteric nodes, but may also spread via the superior rectal, inferior mesenteric, splenic, and portal veins to the liver. An inebriated 40-year-old man was involved in a fight over a woman. The woman’s husband gave the man a severe blow on the lower part of the anterior abdominal wall, whereupon he doubled up with pain and collapsed on the floor. On admission to the emergency department of the local hospital the man was in a state of shock and complaining of severe pain in the lower abdominal region. He was unable to pass urine since the fight. A diagnosis of ruptured urinary bladder was made. 3. The following statements concerning this patient are correct except which? (a) Rectal examination revealed a bulging backward of the rectovesical fossa. (b) Although the patient had consumed a considerable volume of liquor, dullness was not present on percussion of the anterior abdominal wall above the symphysis pubis. (c) The urine accumulated in the rectovesical pouch. (d) A full bladder is more likely to be ruptured by a blow on the anterior abdominal wall than an empty bladder. (e) In the adult as the normal bladder fills, its superior wall extends upward into the abdomen, leaving the covering of parietal peritoneum behind. View Answer3. E. In the adult as the normal bladder fills, its superior wall bulges upward into the abdomen, peeling off the peritoneum from the posterior surface of the anterior abdominal wall. A 56-year-old woman was seen by her obstetrician and gynecologist complaining of a “bearing-down” feeling in the pelvis and of a low backache. On vaginal examination, the external os of the cervix was found to be located just within the vaginal orifice. A diagnosis of uterine prolapse was made. 4. The following anatomic statements concerning uterine prolapse are correct except which? (a) The most important support to the uterus is the tone of the levator ani muscles. (b) The transverse cervical, pubocervical, and sacrocervical ligaments play an important role in supporting the uterus. (c) Damage to the levator ani and the cervical ligaments during childbirth can be responsible for prolapse of the uterus. (d) Prolapse most commonly reveals itself before menopause. (e) Prolapse of the uterus is always accompanied by some prolapse of the vagina. View Answer4. D. Prolapse of the uterus most often reveals itself after menopause, when the pelvic fascia tends to atrophy. A 25-year-old woman was seen in the emergency department complaining of severe pain in the right iliac region. Just before admission she had fainted. On physical examination, her abdominal wall was extremely tender on palpation in the lower right quadrant, and some rigidity and guarding of the lower abdominal muscles were noticed. A vaginal examination revealed a rather soft cervix with a circular external os. A tender “doughlike mass” could be felt through the posterior fornix. The patient had missed her last period. 5. The following statements concerning this patient are correct except which? (a) A diagnosis of ruptured ectopic pregnancy was made. (b) Tubal pregnancies commonly occur where the ampulla narrows to join the isthmus. (c) Each uterine tube is situated in the base of the broad ligament. (d) An ectopic tubal pregnancy almost invariably results in rupture of the tube with severe intraperitoneal hemorrhage. (e) Tubal rupture occurs as a result of the eroding action of the trophoblast. (f) Once a tubal pregnancy dies, the decidual lining of the uterus begins to be shed because of lack of hormonal support, and this causes vaginal bleeding. (g) The doughlike mass is produced by the accumulation of blood in the pouch of Douglas. View Answer5. C. Each uterine tube is situated in the upper free margin of the broad ligament. A 39-year-old woman was admitted to the local hospital after experiencing a gunshot wound to the lower part of her back. Radiographic examination revealed that the bullet was lodged in the vertebral canal at the level of the third lumbar vertebra. A comprehensive neurologic examination indicated that a complete lesion of the cauda equina had occurred. 6. The following statements concerning this patient are likely to be true except which? (a) The cauda equina, which consists of anterior and posterior nerve roots below the level of the first lumbar segment, was sectioned at the level of the third lumbar vertebra. (b) The preganglionic sympathetic nerve fibers to the vesical sphincter that descend in the anterior roots of the fourth and fifth lumbar nerves were sectioned. (c) The preganglionic parasympathetic fibers to the detrusor muscle that descend in the anterior roots of the second, third, and fourth sacral nerves were sectioned. (d) The patient would have an autonomous bladder. (e) The bladder would fill to capacity and then overflow. (f) Micturition could be activated by powerful contraction of the abdominal muscles and manual pressure on the anterior abdominal wall in the suprapubic region. View Answer6. B. The preganglionic sympathetic nerve fibers to the vesical sphincter descend in the anterior roots of the first and second lumbar nerves and were left intact. A 65-year-old man with a history of prostatic disease was found on radiologic examination of his skeleton to have extensive carcinomatous metastases in the skull and lumbar vertebrae. The PSA level in his blood was found to be excessively high. 7. The following statements concerning this patient are correct except which? (a) The patient has advanced carcinoma of the prostate that has spread some distance from the primary site. (b) The prostate is surrounded by the prostatic venous plexus, which drains into the internal iliac veins. (c) Large veins with valves connect the prostatic venous plexus to the vertebral veins. (d) Coughing, sneezing, or straining at stool can force the blood from the prostatic plexus into the vertebral veins. (e) Dislodged cancer cells can be carried with the blood to the vertebral column and skull. View Answer7. C. The large veins that connect the prostatic venous plexus to the valveless vertebral veins are also devoid of valves. A 72-year-old woman was suspected of having a tumor of the sigmoid colon. The physician decided to confirm the diagnosis by performing a sigmoidoscopy. 8. The following anatomic statements are correct concerning the procedure of sigmoidoscopy except which? (a) After inserting the instrument into the anus, the lighted end enters the ampulla of the rectum after a distance of about 1.5 in. (4 cm). (b) Some side-to-side movement may be necessary to avoid the transverse rectal folds. (c) The rectosigmoid junction will be reached approximately 6.5 in. (16.25 cm) from the anal margin. (d) To negotiate the rectosigmoid junction, the tip of the sigmoidoscope should be directed anteriorly and to the patient’s left. (e) Stretching of the colonic wall may give rise to colicky pain in the upper part of the abdomen in the region of the xiphoid process. View Answer8. E. Colicky pain from the colon is referred to the lower part of the anterior abdominal wall above the symphysis pubis. P.383
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Review Questions Multiple-Choice Questions Select the best answer for each question. 1. The following statements concerning the uterus are correct except which? (a) The fundus is part of the uterus above the openings of the uterine tubes. (b) The long axis of the uterus is usually bent anteriorly on the long axis of the vagina (anteversion). (c) The nerve supply of the uterus is from the inferior hypogastric plexuses. (d) The anterior surface of the cervix is completely covered with peritoneum. (e) The uterine veins drain into the internal iliac veins. View Answer1. D. The anterior surface of the cervix lies in direct contact with the posterior surface of the urinary bladder and there is no peritoneum separating the two structures. 2. The following statements concerning the ductus (vas) deferens are correct except which? (a) It emerges from the deep inguinal ring and passes around the lateral margin of the inferior epigastric artery. (b) It crosses the ureter in the region of the ischial spine. (c) The terminal part is dilated to form the ampulla. (d) It lies on the posterior surface of the prostate but is separated from it by the peritoneum. (e) It joins the duct of the seminal vesicle to form the ejaculatory duct. View Answer2. D. The ductus (vas) deferens lies in direct contact with the posterior surface of the bladder. The inferior end of the ampulla narrows down and joins the duct of the seminal vesicle to form the ejaculator duct. 3. The following statements concerning the pelvic part of the ureter are correct except which? (a) It enters the pelvis in front of the bifurcation of the common iliac artery. (b) The ureter enters the bladder by passing directly through its wall, there being no valvular mechanism at its entrance. (c) It has a close relationship to the ischial spine before it turns medially toward the bladder. (d) The blood supply of the distal part of the ureter is from the superior vesical artery. (e) It enters the bladder at the upper lateral angle of the trigone. View Answer3. B. The ureters pierce the bladder wall obliquely, and this provides a valvelike mechanism that prevents urine from reentering the ureter from the bladder cavity. 4. The following statements concerning the seminal vesicle are correct except which? (a) The seminal vesicles are related posteriorly to the rectum and can be palpated through the rectal wall. (b) The seminal vesicles are two lobulated organs that store spermatozoa. (c) The upper ends of the seminal vesicles are covered by peritoneum. (d) The function of the seminal vesicles is to produce a secretion that is added to the seminal fluid. (e) The seminal vesicles are related anteriorly to the bladder, and no peritoneum separates these structures. View Answer4. B. The seminal vesicles do not store spermatozoa; they produce a secretion that nourishes the spermatozoa. 5. The following statements concerning the ovary are correct except which? (a) The lymph drainage is into the para-aortic (lumbar) lymph nodes at the level of the first lumbar vertebra. (b) The round ligament of the ovary extends from the ovary to the upper end of the lateral wall of the body of the uterus. (c) The ovarian fossa is bounded above by the external iliac vessels and behind by the internal iliac vessels. (d) The left ovarian artery is a branch of the left internal iliac artery. (e) The obturator nerve lies lateral to the ovary. View Answer5. D. The right and the left ovarian arteries are branches of the abdominal aorta at the level of the first lumbar vertebra. 6. The following statements concerning the nerve supply to the urinary bladder are correct except which? (a) The sympathetic postganglionic fibers originate in the first and second lumbar ganglia. (b) The parasympathetic postganglionic fibers originate in the inferior hypogastric plexuses. (c) The afferent sensory fibers arising in the bladder wall reach the spinal cord via the pelvic splanchnic nerves and also travel with the sympathetic nerves. (d) The parasympathetic preganglionic fibers arise from the second, third, and fourth sacral segments of the spinal cord. (e) The parasympathetic postganglionic fibers are responsible for closing the vesical sphincter during ejaculation. View Answer6. E. The sympathetic nerves are responsible for the contraction of the sphincter vesicae during ejaculation. 7. The following statements concerning the vagina are correct except which? (a) The area of the vaginal lumen around the cervix is divided into four fornices. (b) The upper part of the vagina is supported by the levator ani muscles and the transverse cervical ligaments. (c) The perineal body lies posterior to and supports the lower part of the vagina. (d) The upper part of the vagina is not covered with peritoneum. (e) The vaginal wall receives a branch of the uterine artery. View Answer7. D. The upper third of the posterior wall of the vagina is covered with peritoneum and is related to the rectouterine pouch (pouch of Douglas). 8. The following statements concerning the visceral layer of pelvic fascia in the female are correct except which? (a) In the region of the cervix of the uterus, it is called the parametrium. (b) It is considered to form the pubocervical, transverse cervical, and sacrocervical ligaments of the uterus. (c) It covers the obturator internus muscle. (d) It does not become continuous above with the fascia transversalis. (e) On the lateral wall of the pelvis, it fuses with the parietal layer of pelvic fascia. View Answer8. C. The obturator internus muscle is covered with the parietal layer of pelvic fascia and is called the obturator internus fascia. 9. The following statements concerning the lymphatic drainage of pelvic structures are correct except which? (a) Lymph from the cervix of the uterus drains into the internal and external iliac lymph nodes. (b) Lymph from the prostate drains into the external iliac lymph nodes. (c) Lymph from the posterior fornix of the vagina drains into the internal and external iliac lymph nodes. (d) Lymph from the trigone of the bladder drains into the internal and external iliac lymph nodes. (e) Lymph from the fundus of the uterus drains into the para-aortic lymph nodes at the level of the first lumbar vertebra. View Answer9. B. The lymph from the prostate drains into the internal iliac nodes. 10. The following statements concerning the main venous drainage of pelvic structures are correct except which? (a) The venous blood from the left ovary drains into the inferior vena cava. (b) The venous blood from the prostate drains into the internal iliac veins. (c) The venous blood from the urinary bladder drains into the internal iliac veins. (d) The venous blood from the mucous membrane of the rectum drains into the superior rectal vein. (e) The venous drainage of the seminal vesicles drains into the internal iliac veins. View Answer10. A. The venous blood from the left ovary drains into the left renal vein. Read the case histories and select the best answer to the question following them. A 3-week-old boy was taken to a pediatrician because of repeated vomiting and reluctance to feed. On questioning, the mother said the child had started to vomit on the first day of life and had vomited at least once a day since then. Early on, the mother had been reassured and told that the baby was taking his feedings too quickly and that the vomiting eventually would cease. While initially accepting this reassurance, the mother now noticed that the child did not seem hungry at feeding time; moreover, she could see that the abdomen was becoming distended. She added that the child definitely was constipated; very occasionally, hard meconium was passed. After a thorough physical examination of the child, the pediatrician made the diagnosis of primary megacolon (Hirschsprung disease). 11. The examination of the child revealed the following possible signs except which? (a) The abdomen was found to be distended. (b) A rectal examination with the gloved little finger resulted in the passage of a large amount of flatus and the abdominal distention became visibly less. (c) A low barium enema followed by a radiographic examination showed a normal rectum. (d) On the radiograph, above the rectum, a narrowed part of the colon led to a funnel-shaped expansion, which in turn led to a greatly dilated descending colon and transverse colon. (e) On placing a stethoscope on the abdominal wall, the physician could not hear sounds of peristalsis. View Answer11. E. In patients with primary megacolon, the muscle of the colon immediately proximal to the obstruction is hypertrophied as the result of attempting to force the meconium and feces onward. Usually very active peristalsis is heard on listening to the abdomen with a stethoscope. After the birth of a baby boy, a moist, red, protruding area was noted on the lower part of his anterior abdominal wall above the symphysis pubis. The pediatrician made the diagnosis of exstrophy of the bladder. 12. On further clinical examination, the following physical signs might have been noted except which? (a) The abdominal skin was seen to be continuous with the margin of the red area. (b) The child had epispadias and bilateral undescended testes. (c) Radiographic examination of the lower abdominal area showed a normal symphysis pubis. (d) On closer examination, jets of urine could be seen discharging through the upper lateral corners of the red protruding area. (e) The scrotum was wide and shallow. View Answer12. C. Exstrophy of the bladder is believed to result from a failure of the embryonic mesenchyme to invade the embryonic disc caudal to the cloacal membrane. This produces an unstable state, which is followed by a breakdown of this area of the abdominal wall with exposure of the red mucous membrane of the trigone of the bladder. This results in the separation of the pubes and anomalies in the development of the external genitalia. P.385
Footnotes *The sympathetic nerves to the detrusor muscle are now thought to have little or no action on the smooth muscle of the bladder wall and are distributed mainly to the blood vessels. The sympathetic nerves to the sphincter vesicae are thought to play only a minor role in causing contraction of the sphincter in maintaining urinary continence. However, in males, the sympathetic innervation of the sphincter causes active contraction of the bladder neck during ejaculation (brought about by sympathetic action), thus preventing seminal fluid from entering the bladder.

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