THE ANTERIOR LIMB 271 



The ulnar artery (a. ulnaris) crosses the uhia obHquely from its 

 origin, reaching in this way the lateral border of the flexor carpi 

 ulnaris, along which it passes to the end of the forearm and to the 

 ulnar side of the pisiform bone. It passes to the ventral surface of 

 the fifth digit, and then turns across the hand, forming the volar 

 arch. 



The single brachial vein (v. brachialis) accompanies the brachial 

 artery and lies behind it. It is formed in front of the elbow by the 

 union of two vessels, the median and ulnar veins, which accompany 

 the corresponding arteries and join one another at the point of 

 separation of the latter. The median vein anastomoses with the 

 radial portion of the cephalic at a point distal to the middle of the 

 forearm. 



The cephalic vein (v. cephalica) is a large superficial vessel 

 appearing on the dorsal surface of the forearm. From the radial 

 side of the latter it receives a large tributary which anastomoses 

 with the median vein. It is accompanied by branches of the super- 

 ficial ramus of the radial nerve. It passes to the front of the arm 

 across the angle of the elbow, lying at first on the anterior margin 

 of the lateral head of the brachialis, and afterwards on the lateral 

 surface of the arm between the acromial portion of the deltoideus 

 and the lateral head of the triceps. It disappears from this surface 

 in the triangular space enclosed by these muscles and the insertion 

 of the levator scapulae major, receiving at this point a large tribu- 

 tary from the shoulder. It appears on the medial surface of the 

 shoulder at the distal end of the axillary border of the scapula 

 between the teres major and the subscapularis; entering the axillary 

 vein at about the same place as the subscapular vein, or in common 

 with the latter. 



The radial nerve (n. radialis) passes behind the brachial artery 

 to the posterior surface of the humerus. It perforates the medial 

 head of the triceps, appearing afterwards on the lateral side of the 

 brachialis in company with the collateral radial artery. A super- 

 ficial ramus, given off on the distal portion of the arm, accompanies 

 the cephalic vein : it passes along the surface of the extensor carpi 

 radialis, dividing into branches for the dorsum of the hand. The 

 remaining portion is chiefly distributed as the ramus profundus to 

 the extensor muscles of the forearm. 



