THE BRACHIAL PLEXUS. 



878, 



from the radial, and afterwards gives off the internal dorsal collateral of the small digit, and 

 external of the auricularis. 



The palmar branch does not extend to all the digits as in the Dog. Passing within the 

 pisiform bone, it divides into several filaments ; some of these are distributed to the muscles of 

 the small digit and thumb ; another follows the external border of the small digit, and con- 

 stitutes its external palri)ar collateral ; one of the longest 



is lodged in the first intermetacarpal space, giving a fila- _Zi?i *'^2- 



ment to the large cushion of the paw, and the internal 

 palmar collaterals of the small digit and external of the 

 annularis. 



Comparison of the Brachial Plexus in Man with 

 THAT of Animals. 



The brachial plexus of Man, like that of the Dog, is 

 constituted by the anterior branches of the four last cervi- 

 cal, and the last dorsal nerves. The few variations ob- 

 served are very slight, and are to be ascribed to the differ- 

 ence in form of the regions to which the nerves are dis- 

 tributed. 



The shoulder of Man being short, and the other seg- 

 ments of the limb long and well detached, the branches 

 of the brachial plexus can be divided into collateral and 

 terminal. 



Tlie coZiafem? branches are: 1. The subclavian branch, 

 whicii is not found in our animals, they having no sub- 

 clavian muscle. 2. The nerve of the levator anguli 

 tcapulx. 3. Nerve of the rhomhovhus. 4. Supra-scapular 

 nerve. 5. The serratus mngnus (posterior ihnracic) nerve. 

 6. Subscapular, which is divided at its origin into two 

 branches as in the Sheep and Cainivora. 7. The nerves of 

 the great and small pectorals (anterior thoracic). The 

 accessory nerve of the internal cutaneous, reprpsented in 

 quadrupeds by the subcutaneous thoracic. 9. The nerve 

 of the latissimus dor si. 10. The nerve of the teres major. 



The terminal branches go to the arm, forearm, and hand. 

 They iire : 



1. The internal cwtoneoMg, which in tije Horse is fur- 

 nished by the ulnar nerve. It becomes subcutaneous at 

 the upper third of the arm, and a little above the elbow 

 bifurcates ; the anterior is spread on the anterior aspect of 

 the arm to the wrist ; the posterior passes backwards, and 

 is expended in the skin of the lack, and inner part of the 

 forearm. 



2. The musculo-cutaneous, or perforans Casserii, the 

 disposition of whicli is analogous to that of Carnivnra. 



3. The axillary nerve, regarding which there is nothing 

 to say. 



4. The radial nerve (musculo- spiral) passes as in 

 animals, lies in the musculo-spiral groove of tiie humerus, 

 gives off an internal and external cutaneous branch, and 

 reaches the antero-external part of the arm. in the space 

 between the anterior brachial and long supinator, where 



NERVES OF THE FRONT OF FORE- 

 ARM AND HAND OF MAN. 



1, Supinator longus (cut) ; 2, ulnar 

 nerve ; 3. brachialis anticus ; 4, 

 biceps; 5, musculo-spiral nerve; 

 6, median nerve ; 7, posterior 

 interosseous nerve; 8, pronator 

 teres and flexor carpi radialis 



(cut) ; 9, extensor carpi radialis 

 longior (cut) ; 10. brachial artery; 11, supinator brevis ; 12, flexor sublimis digitorum (cut); 

 13,13, radial nerve; 14, 14, flexor carpi ulnaris ; 15, extensor carpi radialis brevier; 16, ulnar 

 artery; 17, radial origin of flexor sublimis digitorum (cut); 18, flexor profundus digitorum; 19, 

 tendon of pronator teres; 20, 20, dorsal branch of ulnar nerve; 21, 21, radial artery; 22, 22, 

 deep branch of ulnar nerve; 23, flexor longus pollicis; 24, abductor minimi digiti ; 25, anterior 

 interosseous nerve; 26, digital branches of ulnar nerve; 27, tendon of supinator longus; 28, one 

 of the lumbricales muscles; 29, pronator quadratus ; 31, tendon of flexor carpi radialis; 33, 

 digital branches of median nerve ; 35, adductor pollicis. 



