162 THE SKELETON. 



row of the carpus, between the scaphoid and cuneiform. The superior surface, con- 

 vex, smooth, and bounded by four edges, articulates with the radius. The inferior 

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

 versely : it articulates with the head of the os magnum and by a long, narrow 

 facet (separated by a ridge from the general surface) with the unciform bone. 

 The anterior or palmar and posterior or dorsal surfaces are rough,"^or the attach- 

 ment of ligaments, the former being the broader and of a somewhat rounded form. 

 The external surface presents a narrow, flattened, semilunar facet for articulation 

 with the scaphoid. The internal surface is marked by a smooth, quadrilateral 

 facet, for articulation with the cuneiform. 



Hold it with the convex articular surface for the radius upward, and the 

 narrowest non-articular surface toward you. The semilunar facet for the scaphoid 

 will be on the side to which the bone belongs. 



Articulations. With five bones : the radius above, os magnum and unciform 

 below, scaphoid and cuneiform on either side. 



CUNEIFORM (Fig. 108). 



The Cuneiform (cuneus, a wedge ; forma, likeness) may be distinguished by 



its pyramidal shape (os pyramidale), and by its having an oval, isolated facet for 



articulation with the pisiform bone. It is situated at the 



,,,. rt,-/.m semilu ? iar - upper and inner side of the carpus. The superior surface 



01 pvnjorm. ^^^ \ i 



presents an internal, rough, non-articular portion, and an 

 external or articular portion, which is convex, smooth, and 

 articulates with the triangular interarticular fibre-cartilage 

 of the wrist. The inferior surface, directed outward, is 



J7 1 ' 



concave, sinuously curved, and smooth for articulation with 

 fomi 108 '~ The left cu ~ the unciform. The posterior or dorsal surface is rough, for 



the attachment of ligaments. The anterior or palmar sur- 

 face presents, at its inner side, an oval facet, for articulation with the pisiform ; 

 and is rough externally, for ligamentous attachment. The external surface, the 

 base of the pyramid, is marked by a flat, quadrilateral, smooth facet, for articula- 

 tion with the semilunar. The internal surface, the summit of the pyramid, is 

 pointed and roughened, for the attachment of the internal lateral ligament of the 

 wrist. 



Hold the bone with the surface supporting the pisiform facet away from you, 

 and the concavo-convex surface for the unciform downward. The base of the 

 wedge (i. e., the broad end of the bone) will be on the side to which it belongs. 

 Articulations. With three bones : the semilunar externally, the pisiform in 

 front, the unciform below ; and with the triangular, interarticular fibro-cartilage 

 which separates it from the lower end of the ulna. 



PISIFORM (Fig. 109). 



The Pisiform (pisum, a pea; forma, likeness) may be known by its small size 

 and by its presenting a single articular facet. It is situated on a plane anterior to 

 F 0r the other bones of the carpus ; it is spheroidal in form, Avith 



cuneiform. its long diameter directed vertically. Its posterior surface is a 



smooth, oval facet, for articulation with the cuneiform. This 

 facet approaches the superior, but not the inferior, border of 

 the bone. The anterior or palmar surface is rounded and 

 rough, and gives attachment to the anterior annular ligament 

 pisiform m ~ The left and to the Flexor carpi ulnaris and Abductor minimi digit! 

 muscles. The outer and inner surfaces are also rough, the 

 former being concave, the latter usually convex. 



Hold the bone with the posterior surface that which presents the articular 

 facet toward you, in such a manner that the faceted portion of the surface is 

 uppermost. The outer, concave surface will point to the side to which it belongs. 



