SUPERFICIAL PALMAR ARCH. 491 



the superficial palmar arch, which sometimes terminates by inosculating with 

 the superficialis volas. 



Relations in the Forearm. In its upper half, it is deeply seated, being covered 

 by all the superficial flexor muscles, excepting the Flexor Carpi Ulnaris; it is 

 crossed by the median nerve, which lies to its inner side for about an inch, and 

 it lies upon the Brachialis Anticus and Flexor Profundus Digitorum muscles. 

 In the lower half of the forearm, it lies upon the Flexor Profundus, being 

 covered by the integument, the superficial and deep fascia, and is placed 

 between the Flexor Carpi Ulnaris and Flexor Sublimis Digitorum muscles. It 

 is accompanied by two vena3 comites ; the ulnar nerve lies on its inner side for 

 the lower two-thirds of its extent, and a small branch from the nerve descends 

 on the lower part of the vessel to the palm of the hand. 



PLAN OF RELATIONS OF THE ULNAR ARTERY IN THE FOREARM. 



In front. 



Superficial flexor muscles. j hftlf 

 Median nerve. j 



Superficial and deep fasciae. Lower half. 



Inner sid. jr \ Outer Ride. 



Flexor Carpi Ulnaris. / uinar \ Flexor Sublimis Digitorum 



Ulnar nerve (lower two-thirds). 



Behind. 



Brachialis Anticus. 

 Flexor Profundus Digitorum. 



At the wrist (Fig. 286), the ulnar artery is covered by the integument and 

 fascia, and lies upon the anterior annular ligament. On its inner side is the 

 pisiform bone. The ulnar nerve lies at the inner side, and somewhat behind 

 the artery. 



In the palm of the hand, the continuation of the ulnar artery is called the 

 superficial palmar arch ; it passes obliquely outwards to the interspace between 

 the ball of the thumb and the index finger, where it occasionally anastomoses 

 with the superficialis volas, and a branch from the radialis indicis, thus completing 

 the arch. The convexity of this arch is directed towards the fingers, its con- 

 cavity towards the muscles of the thumb. If the thumb be put at right angles 

 to the hand, the position of the superficial palmar arch will be roughly indi- 

 cated by a line drawn along the lower margin of the thumb across the palm of 

 the hand ; the deep palmar arch is situated about a finger's breadth nearer to 

 the carpus. 



The superficial palmar arch is covered by the Palmaris Brevis, the palmar 

 fascia, and integument ; and lies upon the annular ligament, the muscles of the 

 little finger, the tendons of the superficial flexor, and the divisions of the 

 median and ulnar nerves, the latter accompanying the artery a short part of its 

 course. 



RELATIONS OF THE SUPERFICIAL PALMAR. ARCH. 



In f r nt - f mm . \ Behind. 



Integument. A 1 Annular ligament. 



: a mans .Brevis, V Hand. 1 Origin of muscles of little finger. 



Palmar fascia. V / Superficial flexor tendons. 



Divisions of median and ulnar nerves. 



Peculiarities. The ulnar artery has been found to vary in its origin nearly in the proportion 

 of one in thirteen cases, in one case arising lower than usual, about two or three incnes below 



