652 



MAMMALIAN" ANATOMY 



The magnum (Fig. 512, 7) in man is the largest bone of the wrist. 

 It is not irregular, as in the cat, and the proximal part, the head (a, b], 

 is rounded, transversely oval, and articulates with the scaphoid and 

 the semilunar. The quadrate body articulates by its ulnar surface (c?) 

 with the unciform, by its radial surface (c) with the trapezoid, and by 

 three facets on its distal surface (/) with the second, third, and fourth 

 metacarpals. 



The unciform (Fig. 512, 8) is wedge-shaped, with the apex (b), 

 which articulates with the semilunar, at the proximal and radial sides. 



FIG. 513. 



FIG. 514. 



BONES OF THE CARPUS, AND THOSE WITH 

 WHICH THEY ARTICULATE. RIGHT HAND, 

 POSTERIOR VIEW. 



Of the upper bones, U is the lower end of the 

 ulna, and R is the lower end of the radius. Of 

 the hones of the carpus, in the first row, S is the 

 scaphoid, L the lunar, C the cuneiform, and P 

 the pisiform bone; and in the second row, T T 

 are the trapezium and trapezoid, M the magnum, 

 and U the unciform bones. 1, the metacarpal 

 bones. 



LEFT HAND, VIEWED IN FRONT, OR ON 

 THE PALMAR SURFACE. 



1, scaphoid bone ; 2, semilunar ; 3, cuneiform ; 

 1, pisiform; 5, trapezium; 6, groove in the 

 latter; 7, trapezoid; 8, magnum; 9, unciform; 

 10, the five metacarpal bones; 11, proximal row 

 of phalanges of the fingers ; 12, middle row ; 13, 

 distal row; 14, 15, phalanges of the thumb. 



The distal base (e, d) articulates with the fourth and fifth metacarpals, 

 the flattened radial side with the magnum, and the sloping, undulating 

 ulno-proximal side (a) with the cuneiform. The palmar surface gives 

 off ,at its ulno-distal angle the unciform process (e) for the attach- 

 ment of the opponens and flexor minimi digiti muscles. 



The Metacarpus (Fig. 514) has five well-developed metacarpals; 

 that of the thumb is much longer than the corresponding metacarpal 

 of the cat. The proximal surfaces of the metacarpals are not so ir- 

 regular, and are more nearly upon one level. The shafts are shorter 

 and more distinctly prismatic ; the distal extremity lacks the crest on 

 the articular surface. 



