PRACTICAL CONSIDERATIONS : SURFACE LANDMARKS. 619 



of insertion of the deltoid and coraco-brachialis, and embraces part of the origin 

 of the brachiaHs anticus and internal head of the triceps, and is therefore, and on 

 account of the intimate attachment of the periosteum (page 272), a not uncommon 

 seat of exostoses. (3) The region is — by reason of the close relation of these mus- 

 cles to the bone — a frequent seat of ununited fracture (page 273). (4) The nutrient 

 artery enters the bone and the superior profunda artery and musculo-spiral nerve 

 wind around its posterior surface at that level, at which also the lesser internal cuta- 

 neous nerve and the basilic vein penetrate the deep fascia, the median nerve crosses 

 the brachial artery, and the ulnar nerve leaves it. 



On the outer surface of the arm below the insertion of the deltoid can be seen 

 the shallow furrow (Fig. 596) between the outer head of the triceps and the brachio- 

 radialis which indicates the position of the external intermuscular septum and of the 

 external supracondyloid ridge (page 273) . 



On the posterior surface of the arm the three heads of tflie ti-lfeeps can be seen 

 when the forearm is strongly extended (Fig. 596). The outer head makes a distinct 

 prominence just beneath the posterior border of the deltoid ; the inner head 

 is less distinct ; the long head comes into view where it descends from between the 

 two teres muscles, and lower in the arm — where it has become tendinous — is indi- 

 cated by a broad, shallow depression ending at the olecranon. The long and outer 

 heads cover the musculo-spiral nerve and superior profunda artery from just beneath 

 the posterior axillary fold to the point where they perforate the external septum. 



On the anterior and inner surfaces of the arm the rounded swell of the biceps 

 and the external and internal bicipital furrows are the most important landmarks. 



^ 



Tendon of flexor 

 carpi radialis 



Fig. 595. 



Extensors 



Biceps 



Deltoid 



Tendon of pal maris 

 longus 



Transverse furrows 



Pronator 

 and flexors 



Internal | P'!^"',- 



k;„:„-*„i brachiahs 



bicipital 



furrow Brachial 



Triceps, long artery 

 and inner heads 



^ 



Antero-median surface of right arm, showing modelling on living subject. 



/ ^ 



Pectoralis 



major 



The elevation of the biceps shades off superiorly into the narrower and less distinct 

 prominence of the coraco-brachialis where it comes into view below and beneath the 

 anterior axillary fold. Inferiorly it narrows externally and merges into the biceps 

 tendon, easily seen passing into the forearm in the deep interval between the rounded 

 supinator and extensor mass on the radial side and the pronator and flexor mass on 

 the ulnar side (Fig. 595). Internally the broader flat slip of bicipital fascia — the 

 inner tendon — may be seen with its sharp upper edge when the forearm is semi- 

 flexed and the biceps is in strong action. The outer bicipital furrow indicates the posi- 

 tion of the subcutaneous cephalic vein. The inner and deeper furrow marks the 

 line of the basilic vein (subcutaneous in its lower half, then subfascial), of the median 

 nerve and the brachial vessels, and in its upper half of the ulnar nerve. To the outer 

 side of the outer furrow from above downward lie the deltoid, the outer head of the 

 triceps, the outer portion of the brachialis anticus and the brachio-radialis, and the 

 common extensor mass (Fig. 596). To the inner side of the inner furrow are seen the 

 coraco-brachialis, the long head and then the inner head of the triceps, the brachialis 

 anticus, and the pronato-flexor mass. • 



At the bend of the elbow anteriorly the subcutaneous veins are often visible. 

 Their arrangement is sufficiently described and figured elsewhere (page 892, 

 Fig. 764). The bicipital fascia passes between the median basilic vein and brachial 

 artery, and, by springing from the inner edge of the biceps tendon, makes that edge 



