216 CIRCULATORY SYSTEM. 



course of the radial artery down the fore-arm is generally 

 much more superficial than usual, as it is placed immediately 

 below the skin. 



Of the Radial Artery. 



The Radial Artery (jTrteria Radialis) is smaller than the 

 ulnar, and extends from the elbow to the hand. In the upper 

 half of the fore-arm it is placed at the bottom of the fissure 

 between the supinator radii longus and the pronator teres mus- 

 cle. Having crossed the insertion of the latter, it runs in front 

 of the radius between the tendon of the supinator and of the 

 flexor carpi radialis. Below the styloid process of the radius 

 it runs between the outer end of the carpus and the extensor 

 muscles of the thumb; it then penetrates to the palm of the hand 

 between the root of the metacarpal bone of the thumb and of 

 the fore finger, above the abductor indtcis muscle. 



The following branches are sent from the Radial Artery. 



1. The Recurrens Radialis arises at the neck of the radius. 

 It winds, externally around the joint between the external con- 

 dyle and the muscles coming from it, and anastomoses with the 

 spiralis of the humeral artery, being distributed in many colla- 

 teral branches, to the joint and to the contiguous muscles. 



2. Several small and irregular muscular branches arise from 

 the radial artery, in its progress to the wrist : they have no ap- 

 propriate names. 



3. The Superficialis Volse arises from the radial about the in- 

 ferior margin of the pronator quadratus muscle. It passes su- 

 perficially over the process of the trapezium to the muscles of 

 the ball of the thumb, and one of its terminating branches joins 

 the arcus sublimis. Sometimes the superficialis volae is the 

 principal branch of the radial. 



4. The Dorsalis Carpi arises from the radial at the carpus, 

 runs across the back of the latter below the extensor tendons, 

 and detaches the posterior interosseous arteries of the back of 



