96 THE SURGICAL ANATOMY OF THE HORSE 



The Interarticular Meniscii or Semilunar Fibro-Cartilages 



These are two discs of fibro-cartilage, which are interposed between 

 the condyles of the femur and the articular surfaces of the tibial 

 tuberosities. In outline they are crescentic and they present two 

 surfaces and two edges. The inner edge is very thin, concave and 

 sharp, and embraces the tibial spine. The outer edge is convex and 

 much thicker. The inferior surface of each disc is moulded to the 

 articular facet of the tuberosity upon which it is placed. 



The superior surface of each shows a depression for the accom- 

 modation of the femoral condyle. 



Upon articulating the distal end of the femur with the proximal 

 extremity of the tibia, it will be seen that there is a marked want of 

 adaptability between the articular surfaces. This is compensated by 

 the presence of the semilunar discs, the upper surfaces of which are 

 moulded on the femoral condyles. An additional function of the discs 

 is to limit concussion in the joint. 



The discs are fixed on the lateral tuberosities by means of five little 

 slips to which the name Coronary Ligaments is given. There is great 

 freedom of flexion and extension between the condyles and the discs, and 

 also slight rotation and lateral movement. 



These discs are important from a surgical point of view inasmuch as 

 they are the seat of Stijie yoint Disease. This takes the form of a chronic 

 chondritis, in the first stages of which post-mortem specimens show 

 simply a dryness of the upper surfaces of the cartilages. This surface 

 later becomes roughened and subsequently a number of small erosions 

 make their appearance, the cartilage being worn through in parts and 

 small areas of bone being visible. This is particularly so in the portion of 

 the cartilage which is next the spine. The cause of the affection is 

 unknown, and it is usually met with in heavy draught horses. Animals 

 so affected will stand for several minutes with the stifle and hock flexed 



