THE CARPAL BONES. 91 



named scaphoid, semilunar, cuneiform, and pisiform ; those of the 

 second or inferior range, trapezium, trapezoid, os magnum, and unci- 

 form. 



The dorsal surface of the carpus is convex, the palmar is concave 

 from side to side, the concavity heing bounded by four prominences, 

 one at the outer and one at the inner extremity of each range. The 

 anterior annular ligament is stretched across the carpus between these 

 prominences, so as to form a canal for the transmission of the flexor 

 tendons. 



The superior surfaces of the scaphoid, semilunar, and cuneiform 

 bones form, when in apposition, a continuous convexity which corre- 

 sponds with the concavity presented by the radius and the interarticular 

 cartilage, while the pisiform bone is attached in front of the cuneiform, 

 with which alone it articulates. The line of articulation between the 

 superior and inferior ranges is concavo-convex from side to side, the 

 trapezium, trapezoid and os magnum bounding a cavity which lodges 

 the external part of the scaphoid, and the os magnum and unciform 

 rising up in a convexity, which is received into a hollow formed by the 

 scaphoid, semilunar, and cuneiform bones. 



The scaphoid bone, the largest and most external of the first row 

 of carpal bones, is of a curved form, and lies Avith its longest axis 

 directed outwards and downwards. Its superior surface, convex and 

 smooth for articulation with the radius, is inclined backwards, so that 

 the posterior surface of the bone is not so deep as the anterior. The 

 internal surface naiTOW from above downwards, articulates with the 

 semilunar bone. The outer extremity, rough superiorly for the attach- 

 ment of ligaments, presents inferiorly an articular convexity, which 

 occupies the hollow formed by the upper surfaces of the trapezium and 

 trapezoid bones, and is continuous with a large concave surface ex- 

 tending over the rest of the inferior aspect of the bone, and articulating 

 with the OS magnum. The fore part of the outer extremity of the 

 scaphoid bone projects forwards, forming one of the tubercles to which 

 the anterior annular ligament is attached. The scaphoid articulates 

 with five bones, viz., the radius, the semilunar, trapezium, trapezoid, 

 and OS magnum. 



The semilunar bone, irregularly cubic, is named from the crescentic 

 concavity from before backwards of its inferior surface, which rests on 

 the head of the os magnum, and frequently also by a bevelled edge 

 slightly on the unciform bone. Its external surface is vertical, and 

 articulates with the scaphoid bone ; its internal surface looks down- 

 wards and inwards, is much deeper and narrower than the external, and 

 articulates with the cuneiform. The convex superior surface, which 

 articulates with the radius, is inclined, like that of the scaphoid, more 

 backwards than forwards and hence the anterior surfiice is deeper than 

 the posterior. The semilunar articulates with five bones, viz., the radius 

 scaphoid, cuneiform, os magnum, and unciform. 



The cuneiform bone is somewhat wedge-shaped, its internal extre- 

 mity, rough for ligaments, forming the blunt narrow end of the wedge. 

 Superiorly it presents an articular surface, which glides upon the 

 triangular cartilage interposed between it and the ulna ; externally it 

 articulates with the semilunar bone, and inferiorly with the unciform, 

 by means of a surface which is concavo-convex from without inwards. 

 Its anterior surface is distinguished from the posterior by a smooth 



