268 IMPORTANT ANATOMICAL LANDMARKS. 



between the anterior and middle thirds indicates its exact 

 position. Its pulsations may be felt, and the artery may 

 be compressed against the head of the humerus. 



The pulsations of the brachial artery, which commences 

 at the lower border of the tendon of the latissimus dorsi 

 muscle, may be felt at the inner edge of the coraco-brachi- 

 alis and biceps muscles. At the bend of the elbow it occu- 

 pies a position midway between the tips of the two condyles. 

 The artery may be compressed against the shaft of the 

 humerus. 



The musculo-spiral nerve lies in the depression above 

 the bend of the elbow, marking the interval between the 

 outer border of the brachialis anticus and biceps muscles, 

 and the inner border of the supinator longus muscle. 



The ulnar nerve lies behind the inner condyle of the 

 humerus, in the depression between it and the olecranon, 

 being in close relation to the side of the latter process. 



By rotating the arm at the wrist the head of the radius 

 may be felt near the elbow, rolling under the finger which 

 searches for its position. The forearm should be flexed. 

 It then lies just in front of the external condyle. 



The veins at the bend of the elbow may be demonstrated 

 by the application of a ligature tied around the arm above, 

 their consequent distension rendering them obvious to the 

 eye and touch. 



The ulnar artery, in the upper fourth of its course, is 

 indicated by a line drawn from the middle of the elbow 

 obliquely inward, and thence, by a line drawn from the tip 

 of the internal condyle to the inner border of the pisiform 

 bone. 



The radial artery follows a course indicated by a line 

 drawn from the middle of the bend of the elbow to the 

 interval at the wrist between the tendons of the flexor 

 communis digitorum and that of the supinator longus 

 muscle. The pulsations of the superficialis volse branch of 

 this vessel, when it is present, may be felt upon the ball of 

 the thumb, the muscles of which it crosses, near their 

 origin, in a direction that continues the line of the radial 

 artery. 



The "anatomist's snuff-box" is the triangular interval 

 between the tendon of the extensor secundi interned ii 

 pollicis, and the parallel tendons of the extensor ossis 

 metacarpi pollicis and the extensor primi internodii pollicis 

 muscles. Forced abduction of the thumb will reveal the 



