ARTICULATION OF THE TIBIA AND FIBULA. 263 



supplied by the posterior ligament. On either side of the liga- 

 ment of the patella its inner face is in contact with the synovial 

 membrane of the joint. ; 



Bursa Mucosa. 



There are two of these in connection with the ligamentum 

 patellae ; one of which is placed superficially between the 

 ligament and the fascia lata. This is the seafrof the enlargement 

 by increase of secretion, known under the name of housemaid's 

 knee. The other is placed between the tibia and the ligamentum 

 patellae, as seen in fig. 66. 



Articulation of the Tibia and Fibula. Superior Articulution. 



The surfaces of the upper extremities of the tibia and fibula, 

 which are articulated with each other, are very small. When 

 the bones are in their natural position, these surfaces are nearly 

 horizontal, that of the tibia looking down, and that of the fibula 

 looking up : they are covered with cartilages, and have a syno- 

 vial membrane. This articulation is supported by some liga- 

 mentous fibres, which have been called anterior superior, and 

 posterior superior ligaments ; it is strengthened also by the 

 external lateral ligament of the knee, and by the tendon of the 

 biceps muscle which is inserted into the upper end of the 

 fibula. 



Inferior Articulation. 



At their lower extremities, the cartilaginous crust, which, on 

 each of them, forms part of the articulating surface with the 

 astragalous, is turned up on their lateral surfaces which are in 

 contact with each other ; so that a small portion (equal in 

 breadth only to one sixth of an inch) of the contiguous surfaces, 

 is covered with cartilage ; the other parts of these surfaces 

 which are very considerable, are attached to each other by the 

 intervention of fibrous or membranous matter, and there is 

 very little motion of the bones on each other. 



There are very strong external ligaments, called the anterior 



