84 THE ANATOMY OF THE HORSE. 



two pits on the external condyle of the femur, where it covers the origin 

 of the popliteus from the lower pit. It descends over the external 

 tuberosity of the tibia, a synovial bm-sa being interposed, and is inserted 

 into the head of the fibula. The internal is longer, but more slender, 

 than the preceding. It is fixed above to a small tiibercle on the inner 

 condyle, plays over the inner edge of the tibial articular surface, and is 

 inserted into the internal tuberosity of the tibia. 



The Posterior Ligament is of a flattened, membranous character, and 

 consists of a superficial and a deep layer, which are separable from each 

 other superiorly, but blended below. Superiorly the ligament is attached 

 to the posterior surface of the femur above the condyles ; below it is 

 inserted into the corresponding surface of the tibia, just below the 

 margin of the articular surface ; while laterally its margins blend with 

 the lateral ligaments. The superficial surface of the ligament is related 

 to the popliteal vessels, and to the gastrocnemius, flexor perforatus, and 

 popliteus muscles. Its deep face serves to support the synovial mem- 

 branes of the joint, and is partly adherent to the semilunar cartilages 

 and posterior crucial ligament. The ligament presents apertures for 

 the transmission of vessels to the interior of the joint. 



Synovial Membranes. These are two in iiumber, one for each condyle 

 of the femur and corresponding part of the ai-ticular surface of the tibia. 

 They are separated from each other by the crucial ligaments in the 

 interior of the joint; while behind, and at the sides, they line the 

 posterior and lateral ligaments. In front they are in contact with the 

 synovial capsule of the femoro-patellar articulation, and are supported 

 by a pad of fat, which separates them from the straight ligaments of 

 the patella. A communication frequently exists in front between these 

 synovial capsules and that for the gliding of the patella. These 

 synovial membranes invest the semilunar cartilages ; and the external 

 one covers, in addition, the tendon of origin of the popliteus, and the 

 common tendon of origin of the flexor metatarsi and extensor of the 

 digit. 



Directions. — The posterior ligament sliould now be cut away; and 

 the patella being thrown down, the synovial membrane and fat should 

 be removed from the fx-ont of the joint. The joint should then be 

 strongly flexed, in order to expose, as far as possible, the crucial liga- 

 ments in the intercondyloid groove. The rims of the semilunar 

 cartilages and their coronary ligaments will at the same time be 



The Crucial Ligaments are two strong fibrous cords stretching between 

 the femur and the tibia, and lodged in the intercondyloid groove. They 

 cross one another somewhat like the limbs of the letter X, and hence 

 their name. They are distinguished as anterior and posterior. The 

 anterior^ the most external of the two, is attached superiorly to the 



