224 



OSTEOLOGY 



Articulations. The navicular articulates with five bones: the radius proximally, greater and 

 lesser multangulars distally, and capitate and lunate medially. 



The Lunate Bone (os lunatum; semilunar bone) (Fig. 222). The lunate bone may 

 be distinguished by its deep concavity and crescentic outline. It is situated in 

 the center of the proximal row of the carpus, between the navicular and triangular. 

 The superior surface, convex and smooth, articulates with the radius. The inferior 

 surface is deeply concave, and of greater extent from before backward than trans- 



For radius 



For lunate 



Tubercle 



For greater 

 multangular 



For capitate 



For lesser multangular 

 FIG. 221. The left navicular bone. 



versely: it articulates with the head of the capitate, and, by a long, narrow facet 

 (separated by a ridge from the general surface), with the hamate. The dorsal 

 and volar surfaces are rough, for the attachment of ligaments, the former being 

 the broader, and of a somewhat rounded form. The lateral surface presents a 



For triangular 



For radius 



For navicular 

 For Jiamate For capitate 



FIG. 222. The left lunate bone. 



narrow, flattened, semilunar facet for articulation with the navicular. The medial 

 surface is marked by a smooth, quadrilateral facet, for articulation with the 

 triangular. 



Articulations. The lunate articulates with five bones: the radius proximally, capitate and 

 hamate distally, navicular laterally, and triangular medially. 



For pisiform 



For lunate 



For triangular 



For hamate 



FIG. 223. The left triangular bone. 



FIG. 224. The left pisiform bone. 



The Triangular Bone (os triquetum; cuneiform bone] (Fig. 223). The triangular 

 bone may be distinguished by its pyramidal shape, and by an oval isolated facet 

 for articulation with the pisiform bone. It is situated at the upper and ulnar side 

 of the carpus. The superior surface presents a medial, rough, non-articular portion, 

 and a lateral convex articular portion which articulates with the triangular articular 

 disk of the wrist. The inferior surface, directed lateralward, is concave, sinuously 

 curved, and smooth for articulation with the hamate. The dorsal surface is rough 

 for the attachment of ligaments. The volar surface presents, on its medial part, 



