104 



Bones of the Upper Extremity. 



Os lunatum 



Os naviculare manus 



Os triquetrum 



Tuberculum ossis navicularis 

 Tuberculum ossis 

 multanguli majoris 



Os multangulum 

 majus 



Os pisi forme 



Hamulus ossis hamuti 



Os multangulum minus 



Os hamatum 



Os capitatum 



130137. Bones of the right carpus, ossa carpi, 



shown singly, from the volar surface. 



The eight ossa carpi (wrist bones') (see also Figs. 138146, 148, 149) are arranged 

 in two transverse rows of four each: the proximal (numbered from the thumb side) consists 

 of the os naviculare manus, os lunatum, os triquetrum, os pisiforme; the distal of the os 

 multangulum majus, os multangulum minus, os capitatum, os hamatum. 



The os nayiculare manus (0. T. scaphoid bone) pivs-nts proximally a convex articular 

 surface (for the radius), on its distal surface, a convex articular surface (for the ossa multangula 

 majus et minus), on the ulnar surface proximal ward a small, almost flat articular surface (for 

 the os lunatum) and distal ward a concave surface (for the os capitatum). On the volar sur- 

 face lies the tuberculum ossis navicularis. 



The OS lunatum (0. T. semilunar bone) presents proximally a markedly convex articular 

 surface (for the radius and for the discus articularis of the joint formed by the forearm witli 

 the hand), distally, a markedly concave articular surface (for the os capitatum and the os 

 hamatum); radialward lies a small, almost flat articular surface for the os naviculare, ulnar- 

 ward a small, flat articular surface for the os triquetrum. 



The os triquetrum (0. T. cuneiform bone) has proximally a small, convex articular 

 surface (for the discus articularis of the joint formed by the forearm with the hand), distally, 

 a large surface curved like the thread of a screw (for the os hamatum), radialward, a small 

 flat one (for the os lunatum) and on the volar surface a small, flat, rounded articular surface 

 (for the os pisiforme). 



The OS pisiforme is a small, egg-shaped bone which dorsalward presents a small, flat, 

 rounded articular surface (for the os triquetrum). 



