1448 



SUKFACE AND SUKGICAL ANATOMY. 



vein, the medial cutaneous nerve of the forearm, and the superficial cubital lymph glands, 

 two or three in number. Extending proximally from the lateral epicondyle to the 

 insertion of the deltoid is the lateral intermuscular septum, which is pierced at the 

 junction of its proximal and middle thirds by the radial nerve. Between the 

 lateral intermuscular septum and the lateral edge of the biceps is the ill-defined 

 lateral bicipital furrow, the floor of which is formed by a strip of the brachialis, 

 and, nearer the elbow, by the brachio-radialis and extensor carpi radialis longus. 



The posterior compartment of the arm is occupied by the triceps, the long head 

 of which can be traced proximally to the axillary margin of the scapula, in front 

 of the posterior border of the deltoid and behind the posterior fold of the axilla. 

 The lateral head of the triceps, after emerging from under cover of the distal part 

 of the posterior border of the deltoid, is continued obliquely along the lateral aspect 

 of the arm as a well-marked muscular elevation. Proximal to the olecranon is 

 the strap-like tendon of insertion of the triceps, which, when the elbow is fully 

 flexed, forms an admirable posterior splint in supracondylar fractures of the 

 humerus. 



The brachial artery, slightly overlapped in the proximal half of the arm by the 

 coraco-brachialis and in the distal half by the biceps, can be felt pulsating through- 

 out the whole length of the anterior part of the medial bicipital furrow. The 



Head of radius 

 Lateral epicondyle 

 Extensor carpi radialis longus 



Radial nerve 



Lateral intermuscular septum. Biceps 

 Axillary nerve 





xtensor carpi radialis brevis 

 Deep branch of radial nerve 



Abductor pollicis longus 



Middle thecal tubercle 

 Styloid process of 

 third metacarpal 



Head of ulna 



Infraspinatus 



Triceps tendon 

 Lateral head of triceps 

 Posterior border of deltoid 

 Long head of triceps 

 Teres major 

 Latissimus dorsi 



. Dorsal border of ulna 



II Flexor carpi ulnaris 

 I Extensor carpi ulnaris 

 Extensor digitorum communis 

 Anconaeus 

 Tip of olecranon 



FIG. 1113. DORSAL ASPECT OF ARM. 



course of the vessel may be mapped out upon the surface by drawing a line from 

 the medial border of the coraco-brachialis, at the level of the posterior fold of the 

 axilla, distally to a point (opposite the neck of the radius) J in. distal to the 

 middle of the bend of the elbow. In ligaturing the vessel, the edges of the 

 coraco-brachialis and biceps muscles, together with the median nerve, furnish valu- 

 able guides to the artery, the mobility of which is often a source of trouble in 

 performing the operation. 



The basilic vein, which is superficial to the deep fascia in the distal third of the 

 arm, is visible in the medial supracondylar triangle and the distal part of the 

 medial bicipital groove. The cephalic vein ascends a little anterior and^edial to 

 the lateral edge of the triceps to reach the interval between the deltoid i^and 

 pectoralis major. 



The surface guide for the median nerve is the same as that for the brachial 

 artery. The ulnar nerve is indicated superficially by a line extending from the 

 lateral wall of the axilla, immediately posterior to the prominence of the coraco- 

 brachialis, to the back of the medial epicondyle ; in the proximal half of the arm 

 the nerve lies close behind the brachial artery under cover of the basilic vein, while 

 in the distal half 'it lies a little posterior to the medial intermuscular septum, 

 partially imbedded in the fibres of the medial head of the triceps. To map out the 

 course of the radial nerve, first mark the point where it pierces the lateral inter- 

 muscular septum, viz., the junction of the proximal and middle thirds of a line 

 extending from the insertion of the deltoid to the lateral epicondyle ; from that 



