74 



cuneiforme articulates with the unciform bone : on the outer or ulnar 

 side of this surface, a small articular facet is marked off, by which the os 

 cuneiforme assists in supporting the huge metacarpal bone of the little 

 finger. Thus the proximal row of carpal bones is brought into contact 

 with the metacarpal series at both its extremities, and circumscribes, 

 with this series, the space including the three distinct bones of the second 

 carpal row. 



425. The trapezoides. 



The proximal articular surface connecting the trapezoides with the 

 scaphoid proper is semicircular and slightly convex ; that which joins 

 with the os magnum is a small circular, subconcave surface. The distal 

 articular surface supporting the second or index metacarpal is convex next 

 the dorsal part of the carpus, and concave towards the palmar side, in 

 the vertical direction, with opposite curvatures in the transverse di- 

 rection. 



426. The os magnum. 



This carpal bone is wedged in between the scaphoides, lunare, trape- 

 zoides, unciforme and middle metacarpal bone, and its rugged dorsal 

 surface is bounded by sides corresponding with each of these bones ; of 

 these the one connected with the scaphoid is the shortest, that joined to 

 the metacarpal bone is the longest : towards the dorsal part of the carpus 

 this surface is divided into two parts by a rough depression ; on the 

 opposite or palmar side a small portion of the articular surface is bent 

 outwards at a right angle, so as to support part of the second metacarpal 

 bone. The chief part of the proximal surface of the os magnum is 

 convex, and is received into the concavity of the os lunare. 



427- The os unciforme. 



The unciform bone has a flat dorsal surface bounded by five sides, and 

 supporting an oblong protuberance extending from the radial margin to 

 the middle of the dorsal surface. Part of the radial side of the dorsal 

 surface bounds a slight vacuity between the os cuneiforme and os 



