236 CLINICAL APPLIED ANATOMY. 



the loss of action of the interossei alone, then the index 

 and middle fingers should also be affected, but in the early 

 stages at least this is not the case. Later all four fingers may 

 assume the typical position, but the ring and little fingers always 

 exhibit it in a more pronounced manner. 



When degeneration of the muscles, cut off from their trophic 

 supply, occurs, great diminution of the hypothenar eminence 

 and some diminution in that of the thenar eminence follows. 

 Intermetacarpal hollows also appear on the dor sum of the hand, 

 particularly noticeable in the first space by the disappearance 

 of the abductor indicis or first dorsal interosseus. 

 Cutaneous . In forearm : 



The palmar cutaneous branch, given off in the lower third 

 of forearm, pierces the deep fascia, passes into the palm 

 superficial to the anterior annular ligament, and is 

 distributed to the skin of the hypothenar eminence and 

 ulnar half of palm. 



The dorsal cutaneous branch often given off as high as in the 

 middle third of the forearm, is directed obliquely back- 

 wards and downwards deep to the tendon of the flexor 

 carpi ulnaris, and becomes cutaneous at the back of the 

 ulnar side of the forearm in its lower fourth. On the 

 dorsum of the hand this branch supplies filaments to 

 the skin of the ulnar side, and terminates by sending 

 branches to the dorsal aspect of the ulnar side of the little 

 finger and the contiguous sides of the ring and little 

 fingers, which supply the skin as low down as the middle 

 of the second phalanx. 

 In hand : 



The superficial branch is purely cutaneous, and like the 

 dorsal branch supplies the skin of the palmar aspect of 

 the ulnar side of the little finger and the contiguous sides 

 of the ring and little fingers to their distal extremity, 

 afterwards turning round on to the dorsal aspect for the 

 supply of the cutaneous structures over the lower half of 

 the second and the whole of the terminal phalanges. 



