////: Horn S 



Fig. 43. 



surface ; (, 'I'\vo disrthiodml facets elongated transversely, cut on the 

 posterior oiitliiit' of the large articular surface. \\ith which they an- (-un- 

 founded by their superior border; they correspond 

 to similar 1'accts on the ulna; 7, Belou tin 

 roughened surface \\hieli extends to the radio- 

 nlnar arch, ami is in contact with an analogous 

 surface of the same bone through the medium of 

 nn interoBseous ligament ; in the Horse this liga- 

 ment rarely ossifies. 



The inferior extremity, flattened from before 

 to behind, presents: 1, Below, an articular sur 

 faee elongated transversely and some\\hat irregu- 

 lar, responding to the four bones in the upper 

 row of the carpus; 2, On the sides, two tube- 

 rosities for ligamcutous insertion, the inli-mtif 

 salient and well circumscribed, the other r.c/r/vwi/ 

 and excavated by a vertical fissure, iu which passes 

 a tendon ; 3, In front, three grooves for the 

 gliding of tendons ; the external is the largest, and 

 vertical like the median ; the internal, the nar 

 rowcst, is oblique downwards and inwards; 4, 

 Posteriorly, a strong transverse ridge which sur- 

 mounts the articular surface and serves for the 

 insertion of ligaments. 



Structure and development. The radius is :t 

 very compact bone, and is developed from three 

 centres of ossification : one for the body and two 

 for the extremities. 



2. Ulna. 



This is an elongated, asymmetrical bone-, in 

 the form of an inverted triangular pyramid, applied 

 against the posterior face of the radius, to which 

 it is united in adult solipcds. It offers for des 

 cription a middle portion and two extremities, 



Middle portion. This has tJtrce facr* wider 



d*. th b?fow, ana thrce M TV v '; i(/l1 1 '" t> "" 1 " 



Sii|M-ru-;xternal tuberositv; joined at the iiilerior extremity of the bone. I ho 

 ii, Uatliu-ulnararticular sur- external face is smooth and nearly phpie. The 

 i-ir.-s for the humcrus; 7, internal is also smooth and slightly hollowed. 



i; ici ,i; ital '' The anterior is formed to correspond to the radius, 



Slialt or body of the radius; . .. 



B, Grooves lor tendoa* antl presents peculiarities analogous to those of 

 the posterior face of that bone. Thus there is 



found in proceeding from above to below: 1, Two small diarthrodial 

 facets; 1 2, 'A rough surface; 3, A transverse groove for the formation of 

 the radio-ulnar arch; 4, A triangular surface, studded with rugosities. 

 which occupies the remainder of the bone to its lower extremity. The lateral 

 borders, external and internal, arc sharp, and, like the anterior face, are in 

 contact with the radius. The posterior border is concave, rounded, and thi<-l<er 

 than the other two. 



Extremities. The superior extremity comprises all that portion which 

 exceeds the articular surface of the radius. It constitutes an enormous 

 1 It is represented in Man by the xnuilltr itjm<>!il m>l<-h 



KXTKUNAL FACE OF TI1K 

 UAIHUS AND ULNA. 



I, Ulua; 2, Point of the ok- 



