MEDIAN NERVE. 



417 



on its inner side to the bend of the elbow. It Fig. 187 



then passes between the two heads of the pronator 



radii teres and flexor sublimis digitorum muscles, > w v;; i 



and runs down the fore-arm, between the flexor 



sublimis and profundus, and beneath the annular 



ligament, into the palm of the hand. 



The Branches of the median nerve are, 



Muscular, 



Anterior interosseous, 

 Superficial palmar, 

 Digital. 



The Muscular branches are given off by the 

 nerve at the bend of the elbow ; they are distri- 

 buted to all the muscles on the anterior aspect 

 of the fore-arm, with the exception of the flexor 

 carpi ulnaris, and to the periosteum. The branch 

 to the pronator radii teres sends off reflected 

 branches to the elbow joint. 



The Anterior interosseous is a large branch ac- 

 companying the anterior interosseous artery, and 

 supplying the deep layer of muscles in the fore- 

 arm. It passes beneath the pronator quadratus 

 muscle, and pierces the interosseous membrane 

 near the wrist. On reaching the posterior aspect 

 of the wrist it joins a large and remarkable 

 ganglion which gives off a number of branches for 

 the supply of the joint. 



The Superficial palmar branch arises from the median nerve at about 

 the lower fourth of the fore-arm : it crosses the annular ligament, and is 

 distributed to the integument over the ball of the thumb and in the palm 

 of the hand. 



The median nerve at its termination in the palm of the hand is spread 

 out and flattened, and divides into six branches, one muscular and five 

 digital. The muscular branch is distributed to the muscles of the ball of 

 the thumb. The digital branches send twigs to the lumbricales muscles 

 and are thus arranged : two pass outwards to the thumb to supply its 

 borders; one to the radial side of the index finger; one subdivides for 

 the supply of the adjoining sides of the index and middle fingers ; and 

 the ^emaining one, for the supply of the adjoining sides of the middle and 

 ring- fingers. The digital nerves in their course along the fingers are 

 situated to the inner side of the digital arteries. Opposite the base of the 

 first phalanx each nerve gives off a dorsal branch which runs along the 

 border of the dorsum of the finger. Near the extremity of the finger the 

 digital nerve divides into a palmar and a dorsal branch ; the former sup- 

 plying the sentient extremity of the finger, and the latter the structures 

 around and beneath the nail. The digital nerve maintains no communica- 

 tion with its fellow of the opposite side. 



* Nerves of front of fore-arm. 1. Median nerve. 2. Anterior branch of muscul 

 spiral or radial nerve. 3. Ulnar nerve. 4. Division of median nerve in the palm 

 to the thumb, lst t 2d, and radial side of 3d finger. 5. Division of ulnar nerve to 

 Bide of 3d and both sides of 4th finger. 



2B 



