DISSECTION OF THE POSTERIOR LIMB. 85 



intercoudyloid groove, and to the external condyle of the femur where 

 it bounds that groove. Its fibres have a slightly spiral arrangement, 

 and extend downwards and forwards to be inserted into the summit of 

 the tibial spine. The 2^osterio7- ligament is longer than the anterior, 

 and is fixed superiorly to the intercoudyloid groove and inner condyle. 

 It extends downwards and backwards to be fixed to a special tubercle 

 on the back of the tibia below the rim of its articular surface. These 

 two ligaments bind the femoral and tibial articular surfaces closely 

 together, and at the same time restrict the movements of the joint, the 

 anterior ligament being put upon the stretch during extension, and fin- 

 ally arresting that movement, while the posterior ligament plays the 

 same part with regard to flexion. 



The Inter-articdlar or Semilunar Fibro-cartilages. These are two 

 crescentic or sickle-shaped pieces of fibro-cartilage, interposed between 

 the condyles of the femur and the articular surface of the tibia. The 

 convex margin of each is turned outwards, and is much thicker than the 

 concave edge, which embraces the tibial spine, and is so thin as to be 

 translucent. The lower surface of each is flattened to rest on the tibia, 

 but the upper surface is hollowed to embrace the femoral condyle. 

 They are fixed in position as follows : — The anterior extremity of the 

 inner fibro-cartilage is fixed into an excavation in front of the tibial 

 spine, while its posterior end is similarly fixed behind the spine. The 

 outer cartilage is fixed by its anterior extremity in front of the spine, 

 while its posterior extremity is bifid, having an upper slip inserted into 

 a depression at the posterior part of the intercoudyloid groove, and a 

 lower into the rim of the tibial articular surface, partly under cover of 

 the posterior interosseous ligament. These slips of insertion at the 

 extremities of the fibro-cartilages are sometimes termed the coronary 

 ligaments, three of which belong to the outer, and two to the inner, 

 fibro-cartilage. Although these insertions serve to prevent the total 

 displacement of the fibro-cartilages, some degree of movement is, never- 

 theless, permitted to the latter ; for it will be noticed, that during 

 flexion they are, as it were, squeezed towards the front of the joint, 

 while in extension they are carried backwards. 



Directions. — If the internal lateral ligament be now cut, and the 

 internal condyle removed with the saw, a better view will be obtained of 

 the crucial ligaments ; after which, complete sepai'ation of the femur and 

 tibia should be effected by cutting the remaining lateral ligament, the 

 crucial ligaments, and the slip of insertion of the external fibro-cartilage 

 at the back of the intercoudyloid groove. This will expose thoroughly 

 the semilunar fibro-cartilages. 



TiBio-FiBULAR ARTICULATION. In the horse the amount of movement 

 permitted between the bones of the leg is very restricted, and not 

 appreciable on the general movements of the limb. Where the head of 



