152 MAMMALIA. 



branches to the integuments on the outer side of the arm. The internal cutaneous 

 nerve is a slender nerve sent off by the ulnar ; it passes down the arm, and, near the 

 inner condyle of the humerus, divides into branches to be distributed on the skin at the 

 ulnar side of the fore-arm. The smaller internal cutaneous nerve is the external 

 branch of the second dorsal after its egress from between the ribs ; it pierces the 

 broadest muscle of the back, and divides into branches to be distributed on the skin at 

 the inner and posterior part of the arm. The musculo-cutaneous nerve arises from the 

 sixth cervical with the outer portion of the median, gives a branch to the pectoral 

 muscle and the coraco-brachial, and then passes off to terminate on the biceps. The 

 median nerve is thus formed ; the sixth cervical having given off the nerve analogous 

 to the usual musculo-cutaneous, the remaining part gives off a branch, which sends one 

 back to the internal brachial muscle behind the tendon of the biceps, and then gives 

 branches to the skin of the fore-arm, in the place of the cutaneous portion of the 

 musculo-cutaneous in man ; it then joins the branch from the seventh cervical and first 

 dorsal nerves, about an inch above the elbow, to form the median nerve, which is 

 small as compared with that in man ; the nerve thus formed passes under the origin of 

 the round pronator muscle, and gives branches to this, the radial flexor muscle of the 

 wrist, and the sublime and deep flexors of the fingers ; it then passes by the side of the 

 radial flexor and between the sublime and deep flexors underneath the annular liga- 

 ment ; it is continued in the hand between the tendons of these muscles, at the division 

 of which it sends off branches ; it gives filaments to the skin of the palm, and a branch 

 to the short prominence corresponding with the thumb and the inner side of the first 

 finger, and a branch to be joined by one from the deep palmar for the outer side of the 

 first finger and the inner side of the second ; another branch also to be joined by a 

 branch from the deep palmar for the outer side of the second and the inner side of the 

 third. The ulnar nerve is formed from the seventh cervical and first dorsal, as well as 

 the inner portion of the median ; it descends behind the inner condyle of the humerus, 

 covered by thick fascia and by part of the sublime flexor muscle ; it then passes down 

 the fore-arm between the flexors of the fingers and the ulnar flexor of the wrist ; in 

 the fore-arm it is much larger than the continuation of the median ; it sends a branch 



