THE CAEPUS. 



221 



The lesser 



Os hamatum 



Pisiform 



multangular 



Os lunatum 



FIG. 



Os triquetrum 



216. THE RIGHT PISIFORM 

 BONE. 



Articular 



of wrist 



IS tor FlG * 215 ' THE KlGHT Os TRIQUETRUM. 



third NOTE / Tte k n e is represented in the centre of the figure 

 in the position which it occupies in the right hand 

 viewed from the volar aspect. The views on either 

 side, and above and below, represent respectively 

 the corresponding surfaces of the bone turned 

 towards the reader. 



dorsally, is directed distally and towards the medial side, 

 articulates with four bones the greater 

 multangular, navicular, and capitate 

 bones, and the second metacarpal. 



Os Capitatum (O.T. Os Magnum). 

 This is the largest of the carpal bones. 

 Its volar surface is rough and rounded. 

 The proximal portion of the bone forms 

 the head, and is furnished with convex 

 articular facets which fit into the hollows 

 on the medial surface of the navicular 

 and distal surface of the os lunatum; that 

 for the latter is medial to and separated 

 by a slight ridge from the navicular artic- 

 ular area. The distal surface, narrow to- 

 wards its volar border and broad dorsally, 

 is subdivided usually into three facets by 

 two ridges that towards the lateral side 

 is for the base of the second metacarpal ; 



the inter- 

 mediate 



facet is for 



the 



metacarpal ; 



whilst the 



medial facet 



of the three, 

 NOTE. The figure to the left repre- not always present, very small and placed near the dorsal 



bTne 8 ; ^that to' ihfright the side of the bon6 ' is for the fourth metacarpal. The lateral 

 dorsal view. surface of the body has an articular area for the lesser 



multangular, not infrequently separated from the navic- 

 ular surface on the head by a rough 

 line, to which the interosseous ligament 

 connecting it with the navicular is at- 

 tached. The medial surface of the body 

 has an elongated articular area, usu- 

 ally deeply notched in front ; or it may 

 be divided anteriorly into a small cir- 

 cular area near the dorsal edge, and 

 a larger posterior part. This latter 

 articulates either singly or doubly with 

 the os hamatum, the interosseous liga- 

 ment which unites the two bones 

 being attached either to the notch or 

 to the surface separating the two articu- 

 lar facets. The dorsal surface is rough 

 for ligaments; it is somewhat constricted 

 below the head, the articular surface of 

 which sweeps round its proximal border. 

 The capitate bone articulates with 

 seven bones the os hamatum, the os 

 lunatum, the navicular, the lesser mult- 

 angular, and the second, third, and 



Navicula 



FIG. 217. THE RIGHT GREATER MULTANGULAR BONE. 



NOTE. The bone is represented in the centre of the figure ^ , -, 



fourth metacarpal bones; occasionally 



in the position which it occupies in the right hand 



viewed from the volar aspect. The views on either 



the fourth metacarpal does not ar- 



ide, and above and below, represent respectively ticulate with the Capitate. 



Os Hamatum (O.T. Unciform 

 B one ). The os hamatum can be readily 

 distinguished by the hook-like process (hamulus) which projects from the distal and 



