58 ANATOMY AND PHYSIOLOGY 



the glenoid cavity of the scapula. The head of the radius is proximal and 

 articulates with the humerus. The head of the ulna is distal. 



The upper end of the ulna is its largest part, and an important bone in the 

 elbow-joint. The lower end of the radius is the largest part, and important in 

 the wrist-joint. Observe that in the long bones of the upper extremity the 

 nutrient foramina are in the shafts and are directed toward the elbow-joint. 

 They transmit nutrient arteries to nourish the bones. 



CARPUS 



The carpal bones (ossa carpi) are eight in numfygr. and are 

 typical "slwrt tones. They are arranged in two slightly curved 



rows the first and second with the con- 

 vexity of the curves turned upward to- 

 ward the radius, the first row articulating 

 with it. 



FIRST Row 



Navicular (os namculare). On the 

 radial side of the wrist, named from its 

 shape which resembles a boat, and marked 

 by a tubercle. 



FIG BONES OF Semilunar (os lunatu m) . Well named 

 CARPUS, DORSAL SURFACE, from its half-moon shape. 



Cuneiform (os triquetrum). Very 

 slightly resembling a wedge. 



Pisiform (os pisiforme). Resembling the half of a split pea, 

 and placed in front of the cuneiform. 



SECOND Row 



Trapezium (os multangulum majus). On the radial side, 

 marked by a ridge. 



Trapezoid (os multangulum minus). The smallest of the 

 carpal bones. 



Os magnum (os capitatum).- The largest, having head, neck, 

 and body. 



Unciform (os hamatum). Named for its unciform or hook- 

 shaped process. 



When the carpus is seen from the front, four prominent points 

 are to be noted, namely the tubercle of the navicular and ridge 



