452 THE INFERIOR EXTREMITY 



On the condyles the line is curved with a downward convexity, 

 and on the medial side it passes through the adductor tubercle. 



Ossification of the Proximal Extremity of the Tibia. 

 A secondary centre appears in the cartilaginous proximal 

 extremity of the tibia shortly before birth, and the epiphysis 

 which it forms includes both condyles and the tibial tuberosity. 

 Occasionally the tibial tuberosity possesses a separate centre 

 of ossification, which appears at the eleventh or twelfth year 

 and soon fuses with the rest of the epiphysis. The proximal 

 epiphysis of the tibia unites with the shaft at about the twenty- 

 fourth year. The epiphyseal line usually passes through the 

 articular surface for the head of the fibula. 



The Patella does not begin to ossify till the third year, but 

 ossification is complete at puberty. 



The Knee -Joint. The Capsule of the knee-joint is 

 strongest on the posterior aspect of the joint, and it is quite 

 distinct on the lateral and medial aspects. Anteriorly it forms 

 a thin fibrous layer closely applied to the outer surface of the 

 synovial membrane, but, proximal to the patella and over the 

 area occupied by the patella, it is entirely deficient. On each 

 side of the patella the capsule depends for its strength on 

 the tendinous expansions of the vasti, lateralis and medialis 

 (p. 409). 



Proximally, the line of attachment of the capsule crosses the 

 epiphyseal line on the lateral and medial condyles, but it remains 

 at least half an inch distant from the margins of the articular 

 surface. Posteriorly the capsule is attached to the proximal 

 margins of the articular surfaces and to the intercondylar line. 

 On this aspect, therefore, the line of attachment of the capsule 

 practically coincides with the epiphyseal line. 



Distally, the capsule is attached to the tibial condyles, a 

 little beyond the margins of the articular surface. 



The Synovial Membrane of the knee-joint is very extensive, 

 and its arrangement is complicated by the presence of the 

 intra-articular ligaments and menisci. It lines the deep aspect 

 of the capsule, from which it is reflected on to those parts of the 

 femur and tibia which are intra-capsular but non-articular. 

 From the antero-distal part of the joint a triangular fold of 

 the synovial membrane passes proximally and backwards, to 

 be attached by its apex to the anterior extremity of the inter- 

 condylar fossa. This fold is termed the patellar synovial fold 

 (ligamentum mucosum), and its free margins are known as the 



