

MUSCLES Of THE FOREARM. T19 



beneath the last muscle, which about the middle of the 

 forearm ends in a flat tendon, which passes under the pos- 

 terior annular ligament, in the same groove with the last 

 muscle, and is inserted into the root of the metacarpal bone 

 of the second or middle finger, on its back part. 

 Function. To extend the wrist and hand. 

 The extensor digitorum communis (Fig. 229) arises 

 from the external condyle, intermuscular ligament, and 

 fascia, tendinous and fleshy. It descends to about the 

 middle of the forearm, where it ends in four tendons which 

 pass in a common groove of the radius under the posterior 

 annular ligament, and on the back of the hand diverge to 

 the roots of the fingers, where they are connected by cross 

 slips, from whence they expand over the whole posterior 

 part of all the- phalanges of the fingers. The portion of 

 this muscle going to the little finger receives .the name of 

 auricularis. A bursa is connected 1 with the tendons of this 

 muscle under the posterior annular ligament, and can be 

 traced along these tendons to the base of the first phalanges. 

 Function. To extend all the fingers. 

 The extensor carpi ulnaris (Fig. 229) arises tendinous 

 from the external condyle, and fleshy from the intermus- 

 cular ligament and fascia; also fleshy from the back part 

 of the ulna. It then descends, crossing obliquely the upper 

 part of the radius and ulna, to end in a strong tendon, 

 which passes through a groove on the back of the ulna, to 

 be inserted into the base of the metacarpal bone of the little 

 finger. A bursa is seen where the tendon passes through 

 the groove of the ulna. 



Function. To extend the wrist and hand. 

 The supinator radii brevis (Fig. 230) arises tendinous 

 and fleshy from the external condyle, external lateral and 

 coronary ligaments, and from a ridge on the outer and 

 upper part of the ulna. On removing the superficial mus- 

 cles attached to the external condyle, it is seen surrounding 

 the outer and upper part of the radius, and inserted into 

 the tubercle of the radius, and into the oblique ridge lead- 

 ing to the insertion of the pronator teres.- 

 Function. To roll the radius outward. 



