9<D ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 126. — The lower ends of the bones of the forearm, and the carpal and metacarpal bones in their 



natural positions, seen from the dorsal surface (f). 

 The preparation was made from a frozen hand, whereby the relative position of the bones could be perfectly determined. 



Fig. 127. — The same preparation seen from the volar surface (|). 



Fig. 128. — The bones of the left hand seen from the dorsal surface (f). 



Fig. 129. — The same preparation seen from the volar surface (f). 



Fig. 130. — Frozen preparation of the bones of the left hand, together with the lower ends of the radius 



and ulna, seen from the dorsal surface (f). 

 Fig. 131. — The same preparation seen from the volar surface (-§). 



All the bones are irregularly shaped and are difficult of description. The navicular (scaph- 

 oid) bone is ellipsoidal; its distal surface is excavated, and the radial border of its palmar 

 surface is provided with a rough tubercle (Fig. 127). The lunate (semilunar) bone is shaped 

 like a half-moon, the triquetrum (cuneiform) resembles a short three-sided pyramid, and the 

 pisiform bone is irregularly spherical. The greater (trapezium) and lesser multangular (trape- 

 zoid) bones are irregularly cubical and the palmar surface of the former exhibits an elongated 

 flattened elevation, the tubercle (Fig. 127). The capitatum or os magnum is the largest bone 

 of the set, and its length is much greater than its breadth; its proximal end is large and forms 

 the head of the bone, which is covered with cartilage. The hamatum (unciform) is also large 

 and irregularly wedge-shaped, and its palmar surface is provided with a flat, slightly curved 

 process, the hamulus or unciform process (Fig. 129). 



The carpal bones do not lie in a single plane, but form an arch which is convex posteriorly 

 and concave anteriorly. The concavity is increased by the two bony prominences which are 

 situated upon both the radial and the ulnar sides of the palmar surface of the carpus and form 

 the carpal groove. The radial carpal eminence (Figs. 127 and 131) is formed by the tubercles 

 of the navicular and greater multangular bones; the ulnar eminence, by the pisiform bone and 

 the hamulus of the hamatum. 



The small, almost spherical pisiform bone is situated only in the palmar surface of the carpus ; 

 all of the remaining carpal bones possess a roughened dorsal and palmar surface. Both surfaces 

 of the four bones situated at the radial and ulnar margins of the carpus, the navicular (scaphoid) — 

 greater multangular (trapezium), triquetrum (cuneiform), and hamatum (unciform) — are con- 

 nected by lateral, radial and ulnar surfaces, but the numerous remaining surfaces (numerous 

 on account of the irregular shapes of the bones) are smooth articular facets covered with cartilage 

 for articulation with each other, with the radius, or with the metacarpal bones. 



The pisiform bone has but a single articular facet for connection with the triquetrum (cunei- 

 form), but all of the remaining carpal bones have several articular surfaces. The most important 

 of these are the following: the navicular (scaphoid) and lunate (semilunar) bones each possess 

 a convex articular surface which articulates with the distal end of the radius; the triquetrum 

 is not connected with the ulna, however, but with an intervening disc of cartilage. Of the joints 

 between the proximal and the distal row of the carpal bones, the most important is that between 

 the convex surface of the head of the capitatum and the concave surfaces of the lunate and 

 navicular bones. 



