KNEE. 83 



there being one synovial cavity common to the patella and 

 anterior part of the femur, with the internal condyle and 

 tibia, containing the internal semilunar cartilage ; and a 

 second common to the external condyle of the femur and 

 tibia, with the head of the fibula, in which is contained the 

 external semilunar cartilage. 



The fibula has been rotated forwards to show a large 

 facet upon the inner surface of its head, that articulates. 

 partly with the femur and partly with the outer surface of 

 the head of the tibia. 



B. 173. Right knee-joint of Koala (Phascolarctus cinereus} 

 opened from behind. 



The head of the fibula shares in the formation of the 

 joint, articulating by a small facet with the side of the 

 external condyle of the femur. A small nodule of cartilage 

 (fabella) in the tendon of the gastrocnemius, articulates by 

 a facet with the posterior surface of the head of the fibula. 

 There is no bony patella. 



B. 174. Lower portion of the right hind limb of a Tasmanian 

 Devil (Sarcophilus [Dasyurus} ursinus) showing the knee- 

 and ankle-joints. The head of the fibula has a small 

 facet upon its apex for articulation with the femur, and a 

 larger one upon its outer side which articulates with a 

 nodule of bone attached by ligament to the shaft of the 

 femur above the external condyle and to the head of 

 the fibula. The external lateral ligament has been divided 

 to show another ligament beneath it, that passes diagonally 

 backwards from the lower and outer surface of the external 

 condyle of the femur, and is attached by two branches to 

 the anterior and posterior surfaces of the head of the fibula. 



B. 175. Right knee-joint of a Fruit Bat (Pteropus edwardsii) 

 opened from in front. There are no interarticular 

 cartilages. 



B. 176. The parts constituting the knee-joint of a Calf (Bos 

 taurus). 



The patella is turned down, to expose the anterior part 

 of the joint ; and on the opposite side the cupsular ligament 



G2 



