PHYSIOLOGY, AND PATHOLOGY OF THE CHIMPANZEE. 409 



, The 'muscido-cutaneous nerve from C 5, C 6, C 7, gives a branch 

 to ttie coraco-brachialis and then pierces the muscle. It then 

 gives a large branch to the biceps. Finally it divides into a 

 muscular trunk to the brachialis anticus, and a cutaneous trunk, 

 which gives a small nerve to the spinator longus. 



Yonv subscapular_nerves Si,iL:e ^vesewt. The two upper ones go 

 to the upper and lower parts of subscapularis. The long sub- 

 scapular communicates with the musculo-spiral nerve and supplies 

 the latissimus dorsi. The lowest nerve supplies the subscapularis 

 and teres major. 



The median nert'>e arises from the anterior divisions of all the 

 nerves forming the plexus. It almost immediately after its 

 formation gives a small branch to the coraco-brachialis. No 

 branches arise in the arm. Just below the bend of tlie elbow it 

 supplies the flexor carpi radi-alis, flexor sublimis, and both heads 

 of the pronator radii teres. Then it communicates with the ulnar 

 nerve by a thick branch. In the middle of the forearm it supplies 

 the radial fibres of the flexor sublimis digitorum. About an 

 inch distal to the radio-carpal joint it bifurcates. The outer 

 division supplies the thenar muscles, first lumbrical, and the skin 

 of the radial side of the index and ulnar side of the thumb. The 

 inner division gives a small twig to the third and fourth lum- 

 bricals. Then it divides to supply adjacent sides of the second 

 and third and fourth digits. The nerve to the second and third 

 digits also supplies the second lumbrical. All the branches pass 

 deep to the superficial palmar arch. 



The circninjiex nerve gives the nerve to the teres minor before 

 it passes through the quadrilateral space. No definite anterior 

 and posterior divisions are present. After giving ofi: the large 

 lateral cutaneous nerve of the a,rm it breaks up into deltoid 

 branches. 



The ulnar nerve arises in common with the median. Its course 

 is much as in Man. In the forearm it supplies the flexor carpi 

 ulnaris and flexor profundus digitorum and communicates with 

 the median nerve. Two inches proximal to the wrist it divides 

 into anterior and posterior divisions. The former supplies the 

 hypothenar muscles, the skin of the adjacent sides of the annu- 

 laris and minimus and the inner side of the minimus ; and the 

 latter goes deeply to supply the palmar interossei. A dorsal 

 branch leaves the main trunk at the level of the pisiform bone 

 and supplies interossei. 



The musmilospiral nerve from the posterior divisions of 6, 7, 

 8, gives ofTa slender, but long, nerve to the dorso-epitrochlearis. 

 Its course is as in Man. In the arm it gives off branches to the 

 triceps and skin as in Man. In the lower part of the arm it 

 supplies the supinator longus and extensor carpi radialis longior. 

 At the bend of the elbow it divides into radial and posterior 

 interosseous nerves. The former runs down to the skin of the 

 wrist. The latter perforates the supinator brevis. It supplies 

 the extensores carpi radialis longior and brevier, and the muscles 



