390 NERVOUS SYSTEM. 



surface of the sixth and seventh nerves (Fig. 159,/). It passes 

 toward the shoulder-joint and suppHes the biceps (Fig^. 160, 4) 

 and coracobrachiaHs muscles. It then passes distad,. resting on 

 the dorsal border of the biceps (4), and supplies the brachialis 

 muscle. Thence it passes dorsad of the biceps to the lateral 

 side, and reaches the integument by passing between the clavo- 

 brachialis and pectoantibrachialis muscles near the elbow; it is 

 then distributed to the skin on the radial side of the ventral sur- 

 face of the forearm, as far as the wrist (Fig. 130, //, page 319). 



8. N. cutaneus medialis (Fig. 160, o). — The medial (or 

 internal) cutaneous nerve rises from the first thoracic. It 

 passes distad along the medial side of the biceps, and at the 

 junction of the second and third thirds of the upper arm reaches 

 the integument by passing between the epitrochlearis and 

 pectoantibrachialis muscles. It then curves spirally about the 

 dorsal border of the forearm and is distributed to the integu- 

 ment of the forearm on the ulnar side, extending nearly to the 

 wrist. 



9. N. medianus (Fig. 160, e). — The median nerve is 

 formed by the junction of three branches, one each from the 

 seventh and eighth cervical with thd brachial artery (^) passing 

 between them, and one from the first thoracic nerve. It 

 accompanies the brachial artery (£■) lying on its medial side, 

 and passes with it through the supracondyloid foramen ; here 

 it is connected by a branch to the musculocutaneous nerve. 

 It passes into the forearm (Fig 161, /?), lying at first beneath 

 the pronator teres (5). Here it gives branches to the pronator 

 teres and flexor muscles (flexor carpi radialis, palmaris longus, 

 five heads of the flexor profundus digitorum, but Jio^ to the 

 flexor carpi ulnaris). Continuing along the forearm, lying on the 

 flexor carpi radialis, it sends a posterior interosseous nerve to 

 the pronator quadratus muscle and branches to the deep and 

 superficial divisions of the flexor sublimis digitorum. It thus 

 supplies the flexor and pronator muscles (except the flexor 

 carpi ulnaris). It then passes into the palm beneath the trans- 

 verse ligament and gives rise to three principal branches. The 

 first of these supplies the integument of the thumb, sending a 

 branch on either side of it; and onto the radial side of the 



