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/PECTORAL GIRDLE AND UPPER LIMB/BONES AND JOINTS

Section 6 – PECTORAL GIRDLE AND UPPER LIMB

CHAPTER 45 – Pectoral girdle and upper limb: overview and surface anatomy

This chapter is divided into two sections. The first is an overview of the general organization of the upper limb, with particular emphasis on the distribution of the major blood vessels and lymphatic channels, and of the branches of the brachial plexus: it is intended to complement the detailed regional anatomy described in Chapters 46 to 50 Chapter 47 Chapter 48 Chapter 49 Chapter 50. The second section describes the surface anatomy of the upper limb.

BONES AND JOINTS

The bones of the upper limb are the clavicle, scapula, humerus, radius and ulna (connected for a large portion of their length by an interosseous membrane) and the bones of the hand, i.e. the carpals, metacarpals and phalanges (Figs 45.1, 45.2).

  

Fig. 45.1  Overview of the bones of the left pectoral girdle and upper limb: anterior view.

  

Fig. 45.2  Overview of the bones of the left pectoral girdle and upper limb: posterior view.

The shoulder girdle is extremely mobile because reciprocal movements at the sternoclavicular and glenohumeral joints enable 180° abduction of the upper limb. Movement occurs in all three planes at the glenohumeral joint.

The elbow joint is a hinge joint. It incorporates the superior (proximal) radio-ulnar joint within its capsule. The proximal and distal radio-ulnar joints permit pronation and supination of the forearm – a unique feature of the primate upper limb.

The range of movement at the condyloid wrist joint, between the distal ends of the radius and ulna and the proximal carpal bones, is supplemented by gliding movements between the carpal bones. The saddle-shaped first carpometacarpal joint, between the trapezium and the base of the first metacarpal, is unique to the primate forelimb and permits opposition of the thumb. The hand is clenched by flexion at the metacarpophalangeal joints, supplemented by gliding movements of the fourth and fifth carpometacarpal joints. In grasping, the thumb is of equal value to the remaining four digits: loss of the thumb is almost as disabling as loss of all of the other digits.

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