n8 THE UPPER EXTREMITY 



palmaris brevis muscle ; beyond this it is placed immediately 

 behind the intermediate part of the palmar aponeurosis. As 

 it is followed from the medial to the lateral side of the hand it 

 will be seen to rest upon (a) the transverse carpal ligament ; 

 (b] the short muscles of the little finger ; (c) the flexor tendons 

 and the digital branches of the median nerve. 



Branches of the Arcus Volaris Superficialis. Small 

 branches proceed from the superficial volar arch for the supply 

 of the integument and adjoining short muscles of the palm. 

 As the ulnar artery leaves the surface of the transverse carpal 

 ligament it gives off its prqfunda branch ; whilst from the 

 convexity of the arch proceed four common volar digital 

 branches. 



The a. volaris profundus is a small vessel, which at once 

 disappears from view by passing backwards in the interval 

 between the abductor digiti quinti and the flexor brevis 

 digiti quinti. It will be traced to its termination in the 

 deep dissection of the palm. 



The four common volar digital arteries supply both sides of 

 the three medial digits and the medial side of the index finger. 

 The first common volar digital artery runs distally upon the 

 short muscles of the little finger, to which it gives twigs, and 

 then it is carried along the medial side of the digit. The 

 second common volar digital artery proceeds towards the interval 

 between the roots of the little and ring fingers, and divides 

 into two branches (collateral or proper volar digital arteries\ 

 which run along the contiguous sides of these digits. The 

 ^third common volar digital artery supplies in like manner 

 the adjacent sides of the ring and middle fingers; whilst 

 the fourth common volar digital artery deals similarly with the 

 contiguous margins of the middle and index fingers. 



There are certain points in connection with these volar 

 digital arteries, during their course in the palm and along the 

 sides of the fingers, which must be noted. In the palm the 

 undivided trunks lie in the intervals between the flexor 

 tendons and volar to the digital nerves and the lumbrical 

 muscles. Along the sides of the fingers they show a different 

 relation to the nerves : the nerves are now on the volar side 

 and the arteries lie dorsal to them. Upon the terminal 

 phalanx the two collateral branches join to form an arch, 

 from which proceed great numbers of fine twigs, to supply 

 the pulp of the finger, and the bed upon which the nail rests. 



