THE MUSCLES AND FASCIA OF THE HAND 



459 



and to the triangular and pisiform bones; laterally, to the lateral margin of the 

 radius; and, in its passage across the wrist, to the ridges on the dorsal surface of 

 the radius. 



Abd. poll. long. 



Ext. carp. rod. long. 

 Ext. carp. rad. brev. 



Fia. 424. The mucous sheaths of the tendons on the back of the wrist. 



The Mucous Sheaths of the Tendons on the Back of the Wrist. Between the dorsal 

 carpal ligament and the bones six compartments are formed for the passage of 

 tendons, each compartment having a separate mucous sheath. One is found in 

 each of the following positions (Fig. 424) : (1) on the lateral side of the styloid pro- 

 cess, for the tendons of the Abductor pollicis longus and Extensor pollicis brevis; 

 (2) behind the styloid process, for the tendons of the Extensores carpi radialis 





