90 



OSTEOLOGY 



with which it articulates. It also internally rotates 

 within the lesser sigmotd cavity of the ulna. Below 

 the head is the neck, which is round and smooth, and 

 affords attachment to the supinator brevis muscle. 



THE SHAFT. It is larger below than above, slightly 

 curved, and convex outward and backward. Below 

 the neck on the inner aspect is an elevation of bone 

 called the bicipital tuberosity, which receives the tendon 

 of the biceps muscle. Below this tuberosity the shaft 

 has three surfaces and three borders. 



THE LOWER EXTREMITY. On the inner side of 

 the lower extremity at right angles to the inferior 

 articular surface is a concave articular facet which 

 articulates with the lower extremity of the ulna; the 

 two are held together by ligaments of the inferior 

 radio-ulnar articulation. To the smooth surface of 

 bone between these articular surfaces is attached the 

 interarticular fibrocartilage of the wrist-joint. 



THE ARTICULATIONS OF THE CARPAL BONES 



The Bones of the Wrist (Carpus). The bones 

 of the wrist, eight in number, are arranged in two 

 rows. Those of the upper row, enumerated from the 



