THE HAND. 



359 



radialis indicis. When one of these branches is large the other two are smaller or 

 lacking altogether. Not infrequently the communication with the radial at this point 

 is in the form of a large branch which passes superficially across the web of the thumb 

 and index finger, and its pulsations can be both seen and felt (Fig. 372). 



Branches. As soon as the ulnar artery passes the pisiform bone it gives off its 

 deep branch which passes down between the abductor and flexor brevis minimi digiti to 

 join the termination of the radial and form the deep palmar arch. From the convexity 

 of the superficial arch four palmar digital arteries are given off. One goes to the ulnar 

 side of the little finger while the other three go down between the metacarpal bones 



Ulnar artery 



Deep branch of ulnar artery 

 Deep branch of ulnar nerve 



Superficial palmar arch 



Palmar digital 

 arteries 



Radial artery 



Superficial volar artery 



FIG. 372. Superficial palmar arch. 



to the webs of the fingers. Here they may receive a small communicating branch 

 derived from the deep palmar arch, and about I cm. (fin.) back from the web 

 divide into collateral digital branches which run along the palmar sides of the fingers. 

 The digital nerves as they accompany the digital arteries are superficial to them. 



The Radial Artery and Deep Palmar Arch. The radial artery reaches 

 the wrist between the brachioradialis and flexor carpi radialis tendons. It then turns 

 sharply toward the dorsum around the extremity of the styloid process of the radius. 

 It crosses the external lateral ligaments and the scaphoid and trapezium bones to 

 enter the palm between the bases of the metacarpal bones of the thumb and index 

 finger. It then passes across the palm to the fifth metacarpal bone, where it receives 



