412 



THE ANATOMY OF THE HORSE 



row, as fai' as the interosseous ligaments, and downwards in a similar manner 

 Neither of the ascending pouches is continuous with the radio-carpal capsule, 

 but the external of the two lower communicates with that of the carpo- 

 metacarpal joint. This fact is sometimes important in punctured wounds 

 of the knee joint. 



2. The kadio-carpal articulation, formed by the union of the lower 

 end of the radius with the upper surfaces of the scaphoid, lunar, cuneiform, 

 and pisiform bones, is a true hinge, but somewhat limited in the amount of 



its motion. The lower end of the cannon-bone can 

 describe fully ninety degrees of a circle around the 

 knee joint as a centre ; but the full extent of this 

 motion is divided between the three several articu- 

 lations to which I have alluded, the radio-carpal 

 taking considerably the largest share. The lower 

 end of the radius presents an irregular articular sur- 

 face, longer from side to side than from before 

 backwards, and a non-articular pit or fossa hollowed 

 out to receive a projection of the lunar bone during 

 the flexion of the joint. On each side of these ai^e 

 the lateral processes. The upper surfaces of the 

 carjml bones are moulded exactly to fit the inferior 

 extremity of the radius, and a loose synovial capside 

 passes from one to the other, extending downwards 

 between the three innermost carpal bones as far as 

 their interosseous ligaments, and sometimes also to 

 the capsule between the pisiform and cuneiform 

 bones. 



The ligaments proper to this articulation, in ad- 

 dition to those common to the whole knee joint, are 

 three. Of these one forms a large rounded cord, 

 attaclied to the radius above, and to the cuneiform 

 bone below, taking an oblique direction downwards, 

 and inwards beneath the common posterior liga- 

 ment. The second, much smaller in size, is ex- 

 tended between the external lateral process of the 

 radius and the pisiform bone, being partially covered 

 by the common external lateral ligament, but allow- 

 ing a small triangular space to intervene, through 

 which the synovial capsule is sometimes protruded 

 in diseased conditions of this joint. The third, still 

 more thin and weak in its fibres, is situated beneath 

 _ from the radius is inserted in the lunar bone, and 



into the interosseous ligament which unites the pisiform and the scaphoid 



bones (see 3, Fig. 49). 



3. The carpo-metacarpal articulation is formed above by the three 

 inferior carpal bones, and below by the heads of the three metacarpal bones, 

 together constituting a limited hinge joint. These surfaces above and 

 below are in close apposition, and are lined by one common syno/ial capsule, 

 which, as already mentioned, communicates with that between the two rows 

 of carpal bones. 



Fic. 47. — Anterior View of 

 THE Left Knee Joint. 



A. Inferior third of the ra- 



dius. 



B. Cuneiform bone. 



C. Lunar bone. 



D. Scai>hoid bone. 



E. Unciform bone. 

 G. The great bone. 

 H. Trapezoid bono. 



K. Superior third of meta- 

 carpus. 



1. Scapho-radial ligament. 



2. Externallateralligament. 



3. 3. Internal lateral liga- 



ment. 



4. 4. Ligaments existing be- 



tween upper row of 

 carpal bones. 



5. 5. Caqio-metacarpal liga- 



ment. 



the second, and arising 



