74 OSTEOLOGY. 



and articulates with the internal part of the distal end of the 

 radius ; the inferior surface is also smooth and articular, con- 

 sisting of an anterior portion, slightly convex, for the os mag- 

 num below, and a posterior concave or cup-shaped one for the 

 trapezoid. 



The scaphoid articulates with four bones — viz., the radius above,, 

 the lunar internally, and the os magnum and trapezoid below. 



LUNAR BONE. 

 (Fig. 16. 2.) 



The lunar bone (os lunare), the middle bone of the upper 

 row, both in size and position, is somewhat wedge-shaped, 

 and has four surfaces, a base, and an apex. The superior 

 surface is all articular, triangular in shape, with a concavity 

 posteriorly ; it articulates with the middle part of the distal end 

 of the radius. The inferior surface is articular, and divided hj 

 a ridge into an oblong, concavo-convex portion, occupying about 

 five-sixths of the surface, and articulating with the os magnum ; 

 and another small, oblong, and flat part,, situated at the antero- 

 external border, and articulating with the unciform bone. The 

 internal surface is excavated and roughened, and possesses 

 three articular projections, which correspond with those on the 

 scaphoid, the external surface having two for the cuneiform 

 bone. The base is rough, somewhat trapezium-shaped, and is 

 placed anteriorly, the apex, rough and tuberous, being directed 

 backwards. 



The lunar articulates with five bones — viz., the radius above, 

 the scaphoid internally, the cimeiform externally, and the oS mag- 

 num and unciform below. 



CUNEIFORM BONE. 

 (Fig. 16. 1.) 



This is the smallest and most external of the bones of the upper 

 row, and has five surfaces ; the superior, which is cup-shaped, 

 articulates with the radius, and the inferior, somewhat concave, 

 with the unciform bone. The external surface is convex and 

 rough, and gives attachment to ligaments, while the internal 

 has two facets which articulate with the lunar; the posterior 



