TEE BRACHIAL PLEXUS 



87S 



Fig. 472 



from tlip radial, and afterwiirds gives off (lie internal dorsal r^ollatrral of the pmall digit, Hiid 

 extenial of the auricularis. 



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

 pieiform bone, it divides into several filaments ; some of these are distrihutod to the muscles of 

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

 stitutes its external palmar collateral : one of the longest 

 is lodged in the first intermetacarpal space, giving a fila- 

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

 palmar collaterals of the small digit and external of the 

 annularis. 



Comparison op the Brachial Pi.exvs in Man with 

 THAT OF Animals. 



The brachial plexus of Man, like that of tlie 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. 



The collateral branches are: 1. The subclavian branch, 

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

 clavian muscle. 2. The nerve of the levator anguli 

 Bcapulse. 3. Nerve of the rhomhoideus. 4. Supra-scapular 

 nerve. 5. The serratus magniis (posterior thoracic) nerve. 

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

 branches as in the Sheep an<l Cai uivora. 7. The nerves of 

 the great and small pectorals (anterior thoracic). The 

 accessory nerve of the internal cutaneous, represented in 

 quadrupeds by the subcntancous thoracic. 9. The nerve 

 of tlie latissimus dorsi. 10. The neri^e of the teres major. 



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

 They are : 



1. The internal cutaneous, which in tliC Horse is fur- 

 Dished by the ulnar nerve. It becomes sulwutaneous at 

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

 bifurcates; tht 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 back, and inner })art of the 

 forearm. 



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

 disposition of which is analogous to that of Camivora. 



3. The axillary nerve, regarding which there is nothing 

 to say. 



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

 animals, lies in the musculn-8(.iial groove of the 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, 

 bireps ; 5, musculo-spiral nerve; 

 6, median nerve ; 7, posterior 

 interosseous nerve; 8, pionator 

 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 bievinr; 16, ulnar 

 artery; 17, r.ndial origin of flexor sublimis digitorum (cut) ; 18, flexor profun<his 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 Inmbricales muscles; 29, jironator quadratus ; 31, tendon of flexor carpi radialis; 33, 

 digital branches «f median nerve ; 35, adductor pollicis. 



