74 OSTEOLOGY. 



and articvilates 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 i-adius. 

 The inferior surface is articular, and divided by 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 bor- 

 der, 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 cuneiform externally, and the os 

 magnum and unciform below. 



CUNEIFORM BONE. 



(Fig. 16. 1.) 



This is the smallest and most external of the bon.es 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 con- 

 vex and rough, and gives attachment to ligaments, while the 

 internal has two facets which articulate with the lunar ; the 



