100 THE SURGICAL ANATOMY OF THE HORSE 



layer is strong and fibrous, and it is perforated by a number of 

 foramina for the passage of blood-vessels. Its fibres intercross. It is 

 attached superiorly to the back of the femur immediately below the 

 origin of the outer head of the gastrocnemius muscle. The deep layer 

 is closely applied to the condyles of the femur, and is attached to the 

 superior edge of their articular surfaces. The two divisions become 

 united and are attached inferiorly to the back of the tibia immediately 

 below the articular surface of the tuberosities. The anterior face of 

 this ligament is covered almost throughout its extent by the two 

 synovial membranes of the femoro-tibial joints and these synovial 

 membranes it supports. 



It also covers the posterior borders of the semilunar discs, and the 

 posterior coronary and insertion of the posterior crucial ligaments. The 

 posterior surface of the ligament is crossed by the popliteal vessels, and 

 is covered by the popliteus muscle. 



Synoz'ial Membranes. — The stifle possesses three synovial membranes, 

 a superior or femoro-patellar, and two laterals or femoro-tibial. 



The superior synovial membrane is very large and loosely applied in 

 order that the patella may glide freely over the femoral trochlea without 

 causing injury to the membrane. It is strengthened and supported by 

 the femoro-patellar capsule. A diverticulum of this membrane is pro- 

 longed beneath the insertion of the tendon of the quadriceps extensor 

 cruris muscle. 



The external membrane lines the joint between the outer femoral 

 condyle and the superior face of the disc of cartilage placed on the 

 external tuberosity of the tibia. It also lines the tendon of origin of the 

 popliteus muscle. An extensive pouch of this membrane descends in 

 the groove between the anterior and external tuberosities of the tibia 

 and envelops the tendon which is common to the extensor pedis and 

 superficial division ofthe flexor metatarsi muscle. 



The internal membrane lubricates the joint between the internal 

 femoral condyle and the upper face of the inner semilunar disc. 



