FOREARM AND HAND 



177 



enters the muscle proximal to the elbow. The main action 

 of the muscle is flexion of the elbow, but it can help to 

 initiate supination of the prone forearm and pronation of 

 the supine forearm. 



M. abductor pollicis longu? 



Radius- 



M. extensor carpi radialis brevis - 

 M. extensor carpi radialis longus- 



Tendon of M. extensor 



pollicis brevis 



Sheath of extensor pollicis brevis 



A. radialis. 

 Sheath of extensor 

 pollicis longus 



M. adductor pollicis 



M. interosseus 

 dorsalis primus 



. extensor digitorum communis 

 M. extensor carpi ulnaris 



Ulna 



M. extensor digiti quinti proprius 



Styloid process of ulna 



Ligamentum carpi dorsale 



Sheath of extensor digiti quinti 

 M. abductor digiti quinti 



Tendon of extensor digitorum /' 



communis 

 Tendon of extensor indicis U 



FIG. 76. Dissection of the Back of the Forearm, Wrist, and Hand, 

 showing Mucous Sheaths of Tendons. 



Dissection. Remove the thin deep fascia of the dorsum of 

 the hand, clear away the mucous sheaths of the tendons and 

 clean the tendons, but do not injure (i) the dorsal carpal liga- 

 ment, (2) the blood-vessels which lie deep to and in the intervals 

 between the tendons, (3) the slips which connect the tendon to 

 the ring finger with that on each side of it. Three tendons must 

 VOL. I 12 



