UPPER EXTREMITY AND THORAX, ANTERIOR. 305 



the adjacent sides of the ring and little fingers. The third 

 takes a similar course and distribution to the middle and 

 ring fingers. The fourth is distributed to the adjoining sides 

 of the index and middle fingers in the same manner. 



These digital arteries lie between the fasciculi of the 

 palmar fascia, and long flexor tendons of the fingers, and 

 upon the lumbrical muscles and digital nerves, and are 

 covered by the palmar fascia. 



Just before they bifurcate they are joined by the inter- 

 osseous branches of the deep arch and the perforating from 

 the dorsal interosseous arteries. The remaining side of the 

 index finger is supplied by the radialis indicis, and the thumb 

 by the princeps pollicis, both from the radial artery. See 

 page 310. 



(3) The muscular and cutaneous branches from the 

 superficial arch are few and small. 



The Digital Nerves. Fig. 66. 



The median nerve supplies two branches to the thumb, 

 one on either side ; a third to the outer side of the index 

 finger ; a fourth, to between the index and middle ; and a 

 fifth, between middle and ring fingers ; each of which sub- 

 divide to supply the contiguous sides of these fingers. 



The third and fourth nerves send a fine branch to the 

 two outer lumbrical muscles, the fifth receives a communi- 

 cating branch from the ulnar nerve. From the ulnar nerve 

 the rest of the fingers are supplied, the first digital branch 

 being given off to the inner side of the little finger, and the 

 second to between the little and ring fingers, which then 

 divides into collateral branches to the adjacent surfaces of 

 these two fingers. From the outer side of the second 

 branch is given a small filament to join the median. See 

 above. From the median nerve just below the annular 



20 



