THE POSTERIOR BRACHIAL REGION. 



487 



and from the middle third of the posterior surface of the shaft of the radius. 



-ing obliquely downward and outward, it terminates in a tendon which runs 

 through a groove on the outer side 

 of the styloid process of the ,radius, 

 accompanied by the tendon of the 

 Extensor brevis pollicis. and is in- 

 serted into the base of the rneta- 

 carpal bone of the thumb. It occa- 

 sionally gives off two slips, near its 

 insertion one to the Trapezium, 

 and the other to blend with the 

 origin of the Abductor pollicis. 



Relations. By irs superficial 

 surf'!'--', with the Extensor com- 

 munis digitorum. Extensor minimi 

 digiti, and fascia of the forearm, 

 and with the branches of the pos- 

 terior interosseous artery and nerve 

 which cross it ; by its deep surface, 



Internal 

 condyle. 



External 

 condyle. 



CAPSULAR 

 LIGAMENT. 



B|NM, 



FIG. 309. Supinator brevis. (From a prepara- 

 tion in the Museum of the Royal College of 

 Surgeons of England). 



EXTENSOR 

 CARPI ULNARIS. 



FIG. 310. Posterior surface of the forearm. Deep muscles. 



with the ulna, interosseous membrane, radius, the tendons of the Extensor carpi 

 radialis longior and brevior, which it crosses obliquely, and, at the outer side of 

 the wrist, with the radial vessels : by its upper border, with the Supinator brevis ; 

 by its luwer border, with the Extensor brevis pollicis. 



