88 



which represents the os trapezium, and supports the metacarpal bone of the 

 thumb. 



This process, or confluent bone, gives to the scaphoid an unciform figure, 

 which the true os unciforme nowise presents. It is short or depressed in the 

 direction of the axis of the hmb, broad from side to side, convex towards the 

 back of the carpus, and made concave on the opposite side by the production 

 of the two angles, and especially of that formed by the anchylosed trapezium. 

 The articulation of the radius covers all the proximal surface, save the trapezial 

 angle ; the surface is very slightly concave at its broad outer part for the recep- 

 tion of the styloid process of the radius, and is convex in the rest of its extent, 

 especially in the direction from the dorsal to the palmar aspect. The articular 

 surface is continued at right angles to its radial portion upon part of the ulnar 

 side of the scaphoid for the junction with the os lunare. The distal surface of 

 the scapho-trapezial bone is excavated by two concave articular surfaces for the 

 OS magnum and trapezoides : these surfaces are separated by a rough concavity 

 from the small and nearly flat one, at the outer side of the trapezial process, for 

 the metacarpal bone of the thumb. The dorsal surface of the scaphoides is con- 

 vex, rough, perforated by vascular canals, and slightly raised between the radial 

 and trapezoidal articulations. The palmar surface is smoother, and presents a 

 narrow groove below the radial articular surface : the chief vascular perforations 

 of the bone are in this groove. 



The OS lunare (6) equals'the scaphoides in size, and resembles a cone or wedge 

 more than a crescent, being much thicker at its dorsal than at its palmar side. 

 The rough dorsal surface is slightly convex transversely, subconcave or flat lon- 

 gitudinally, bounded by six sides, of which the upper, forming the margin of 

 the convex articular surface for the radius, is the longest : the two lateral sur- 

 faces are the shortest ; of these, the one next the scaphoides is concave : the 

 remaining three sides, which are straight, bound two angles ; one of these is 

 applied to the interspace between the cuneiform and unciform bones ; the other, 

 which is longer and more acute, is wedged into the angle between the os mag- 

 num and cuneiforme. The narrow palmar side of the lunare forms a rough 

 convex protuberance on that aspect of the carpus. The radial articular surface 

 is nearly flat transversely, but describes a semicircular curve from behind for- 

 wards : it is continuous with the narrow lateral one joining with the scaphoides. 



