41: 



TIIK ANATOMY OF TIIK HOrxSE 



row, !is far as the interosseous ligaments, and downwards in a similar manner 

 Nfillier of the ascending pouches is continuous with the radio-carpal capsule, 

 hut the external of the two lower ct)mnuinicates with that of the carpo- 

 metacarpal joint. This fact is sometimes important in punctured wounds 

 of the knee joint. 



2. The it.vDio-rAiU'AL ahticulatiox, 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. 2'he 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 are 

 the lateral processes. The upper surfaces of the 

 carpal hones 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 intero-sseous ligaments, and sometimes also to 

 the capsule between the pisiform and cuneiform 

 bones. 



The li(/aments 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, 

 attached to the radius above, and to the cuneiform 

 bone below, taking an obli(|ue 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 

 the second, and arising 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 liinge joint. These surfaces above and 

 below arc in close apposition, and are lined In- one common synovial capsule, 

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

 of carpal bones. 



J 



Vtn. 4T. — AxTERK ill View ok 

 TIIK I>£iT Knee Joi.st. 



A. Inferior third of the ra- 



dius. 



B. Cumnronn bono. 



C. Lunar l)onp. 



1). .Si-ajdioid bono. 

 K. L'ncifonn liono. 

 1;. The gTt'.it Ixme. 

 II. Trajx-zoid Ixm.-. 

 K. Sui>orior thinl of meta- 



i-ari u-. 

 1. .Sraj ' .,i,.iit. 



•J. Ext. .-.m.-iit. 



8. 3. Ii ■ ■ a li-ii- 



nii'iii. 



4. 4. Li^inenta existing lx>- 

 twt-en upper row of 

 rar|>al tKjno«. 



6. 5. Cariio-uicUcarpal liga- 

 ment. 



