280 DISSECTION OF THE HAND. 



two metaearpal bones ; and to lay bare the vessel, it will be requisite to 

 detach the origin of the flexor brevis pollicis. The deep palmar arch, and 

 the branch of the ulnar nerve accompanying it, together with their offsets, 

 are to be dissected out. 



A fascia, which covers the interossei muscles, is to be removed, when 

 the dissector has observed its connection with the transverse ligament 

 uniting the heads of the metacarpal bones. 



RADIAL ARTERY IN THE HAND (fig. 84). The radial artery enters 

 the palm at the first interosseous space, between the heads of the first dorsal 

 interosseous muscle : and after furnishing one branch to the thumb, and 

 another to the index finger, turns across the hand towards the ulnar side, 

 with its venae comites, forming the deep arch. 



The deep palmar arch (c) extends from the interosseous space to the 

 base of the metacarpal bone of the little finger, where it joins the profunda 

 communicating branch (b). Its convexity, which is but slight, is directed 

 forwards ; and its position is nearer the carpal bones than that of the 

 superficial arch. The arch has a deep position in the hand, and lies on 

 the metacarpal bones and the interossei muscles. It is covered by the 

 long flexor tendons, and in part by the flexor brevis pollicis. The branches 

 of the arch are the following : 



a. Recurrent branches pass from the concavity of the arch to the front 

 of the carpus ; these supply the bones, and anastomose with the other carpal 

 arteries. 



b. Three perforating arteries pierce the three inner dorsal interossei 

 muscles, and communicate with the interosseous arteries on the back of 

 the hand. 



c. Usually there are three palmar interosseous arteries (/), which 

 occupy the three inner metacarpal spaces, and terminate by joining the 

 digital branches of the superficial palmar arch at the cleft of the fingers. 

 These branches supply the interosseous muscles, and the two or three inner 

 lumbricales ; they vary much in their size and distribution. 



d. Digital branches of the radial. The large artery of the thumb (V) 

 (art. princeps pollicis) runs between the first metacarpal bone and the 

 flexor brevis pollicis, to the interval between the heads of the muscle, 

 where it divides into the two collateral branches of the thumb : these are 

 distributed like the arteries of the superficial arch. 



e. The digital branch of the index finger (T) (art. radialis indicis) is 

 directed over the first dorsal interosseous muscle, j, and beneath the short 

 flexor and the adductor pollicis, to the radial side of the forefinger. At 

 the free or anterior border of the adductor pollicis, D, this branch is usually 

 connected by an offset with the superficial palmar arch ; and at the end of 

 tin- digit it unites with the branch furnished to the opposite side by the 

 ulnar artery. 



The deep branch of the ulnar nerve ( 2 ) accompanies the arch of the 

 radial artery as far as the muscles of the thumb, and terminates in offsets 

 to the adductor pollicis and the inner head of the short flexor. 



Branches. Near its origin the nerve furnishes branches to the muscles 

 of the little finger. In the palm it gives offsets to all the palmar and 

 dorsal interosseous muscles, and to the inner two lumbrical muscles ( 3 ), 

 besides the terminal branches before mentioned. 



The transverse metacarpal ligament connects together the heads of the 

 four inner metacarpal bones. Its cutaneous surface is hollowed where the 

 flexor tendons cross it ; and beneath the interossei muscles pass to their 



