THE MEDIAN NERVE 



991 



passes through the fibres of the opponens digiti quinti to reach the deep surface of the flexor 

 tendons and their s>Tiovial sheaths. It supphes the abductor and opponens digiti quinti, the 

 flexor digiti quinti brevis, the third and fourth lumbricales, all the interossei, the adductors of 

 the thumb, and the medial head, and occasionally the lateral head, of the flexor pollicis brevis. 

 The superficial branch gives otf a branch to supply the palmaris brevis muscle, an anastomosing 

 branch to the median nerve, and then divides into two branches, the proper volar digital branch, 

 which is distributed to the medial side of the fifth digit on its volar aspect, and the common 

 volar digital branch, which passes underneath the palmar aponeurosis and divides into two 

 branches, which supply the contiguous margins of the fourth and fifth digits. These branches 

 usually supply also the dorsal sm-face of the second and third phalanges of the same digits. 



The median nerve contains fibres of the sixth, seventh, and eighth cervical 

 nerves and of the first thoracic, and sometimes of the fifth cervical nerve. The 

 trunk is formed a little below the lower margin of the pectoralis minor, by the 



Fig. 761. — Nerves op the Palmar Surface of the Hand. (Testut.) 



The transverse carpal (anterior annular) ligament, superficial palmar arch, the flexor tendons 



of the digits, and the proximal portions of the lumbrical muscles have been removed. 



Superficial radial 



Palmar branch of median 



Branches of superficial radial 



Branches of first common 

 volar digital 



Branch to adductor pollicis 

 Proper volar digital 



Ulnar nerve 



Deep branch of ulnar 

 ^ ^^Dorsal branch of ulnar 



Superficial branch 



^ — Muscular branch 



,^ Palmar cutaneous branch 



— Branch to lumbrical IV 

 —Common volar digital 

 ■Proper volar digital 



union of two components, one from the medial and one from the lateral cord of 

 the brachial plexus (fig. 755). The medial component passes obliquely across the 

 third part of the axillary arteiy, and in the upper part of the trunk the fibres of the 

 two components are felted together. From its commencement the median nerve 

 runs almost vertically through the lower part of the axillary fossa and through the 

 arm and forearm to the hand. 



In the fossa it lies lateral to the axillary artery and it is overlapped, on its lateral side, by 

 the cqraco-brachialis muscle. In the upper half of the arm it hes along the lateral side of the 

 brachial artery, and it is overlapped by the medial border of the biceps. At the middle of the 

 arm it passes in front of the brachial artery, and then it descends, on the medial side of the artery, 

 to the elbow. In the upper part of the antecubital fossa it is still at the medial side of the bra- 

 chial artery, but separated from it by a small interval, and in the lower part of the fossa it Hes 



