44 



THE BONKS AND JOINTS. 



ulnar portion of the bone forms a cap'iluliini. The structure of 

 the inferior extremity is that of epiphyses in general, except that 

 there are two medullary cavities in a common sheath of calcified 

 cartilage; the anterior head consists of cancellous tissue, with a 

 covering 1 of calcified cartilage. 



Fig- 39- 



Bones of the forearm and hand of li'inu 

 fsculenta, right side, dorsmn, twice 

 nat. size. 



a Os antibrachii. 



he Os capitato-hamatuin. 



I Os lunatuin. 



m Ossa metacarpi. 



n Os naviculare. 



/) < I* pyramidale. 



Radial portion of the r.ulio-uliiar. 



t Os multiingulum niajus or trapezium. 



(' Os multangulum minus or trapezi lide.-,. 



u Ulnar portion of the radio-ulnar. 



/ V First to fifth fingers, the fifth only 

 of os nietacarpi, the second and third 

 of two, fourth and fifth of three 

 phalanges. 



3. Bones of the hand (Fig. 39). 



Duges, PI. VIII, Figs. 37, 38, 39, 40, 41, 



4 2 > 43. 52. 



a. Bones of the wrist, oxsa cai'ju. 

 These are arranged in two rows, proxi- 

 mal and distal. The proximal or an- 

 terior row has three bones, viz. : 



1. Os liutafti.il!, the middle bone (Fig. 

 39 1], Duges, 11. 38, articulates with the 

 radial part of the articular surface of 

 the radio-ulnar by a concave surface; 

 with the large bone of the second row 

 (tic) it articulates by means of a rounded 

 head; and with the two other bones 

 of this row, os naviculare (n] and jij/rtt- 

 midale (p], with the former by a saddle- 

 shaped surface, with the latter chiefly 

 by ligament. The bone is irregularly 

 cuboid ; the dorsal and palmar surfaces 

 are non-articular. With Duges I regard 

 this bone as os lunatuin ; Mertens l re- 

 gards it as os naviculare. 



2. Os pyramid ale (Fig. 39^), Duges, 

 n. 37, articulates with the ulnar part 

 of the posterior articular extremity of 

 the radio-ulnar. Anteriorly the bone 

 has a facet which receives the capt lu- 

 lu m ulnae, and alongside this a small 

 flat surface which articulates with the 

 radius. Posteriorly, opposite to the 

 second row, it presents a long raised 

 articular surface, extending from the 

 dorsum to the palmar surface ; and on 



1 Merteus. 1. c. 



