158 



Anatomy of Skeleton 



inner 

 cmdylt 



fibres of its posterior ligament come down below the level of the tibia (transverse 



lig.) and will be considered with the ankle joint (p. 174). 



Fastened in this way there is still a very slight amount of movement possible 



between the bones, but it is so small that it may be practically disregarded and the 



fibula looked on as securely attached to the tibia, not carrying any weight, but com- 

 pleting and strengthening the articular 

 surface of the ankle on the outer side, 

 and affording, with the tibia and mem- 

 brane, a firm ground for the origin of 

 muscles. 



The fibula is excluded from the 

 cavity of the knee, although the outer 

 ligaments of this joint reach it : the upper 

 end of the tibia carries the femur and 

 fibro-cartilages, has synovial and articular 

 relations, and directly transmits the 

 weight from the femur. 



The knee joint is a hinge joint, in 

 which, however, there is possible a certain 

 small amount of rotation during flexion, 

 and exists between femur, patella, and 

 tibia. There is a single cavity between 

 femur and patella, carried back as two 

 condylar cavities under each condyle 

 between femur and tibia. The condyles 

 rest partly on rings of fibro-cartilage, 

 the semilunar cartilages, between them 

 .and the tibia, to which the rings are 

 fastened, and there are strong crucial 

 ligaments connecting femur and tibia and 

 placed between the two condylar cavities : 

 these condylar cavities pass back on each 

 side of the crucial ligaments, and turn up 

 behind the condyles to reach the bone 

 just above the articular surfaces. The 

 whole is surrounded by ligamentous 

 coverings. 



The upper articular aspect of the tibia 

 naturally corresponds with the lower 

 surface of the femur that is, there are 

 two surfaces on which the condyles rest, 

 with an intervening crest for ligamentous attachments, and the inner surface is 

 longer and rather narrower than the outer, as is the case in the femoral condyles. 

 The semilunar fibro-cartilages which are interposed between the bones also exhibit 

 corresponding differences, for the inner one forms a more oval figure than the outer 

 (Fig. 130). 



The outer cartilage more nearly completes a circle,' so that its ends, or cornua, 

 are closer together than those of the inner meniscus, thus placing the order of their 

 attachment to the tibia as in Fig. 131. The two cornua of the outer cartilage are on the 



interior 



Fie. 130. Parts of a right knee to show the 

 correspondence between them. The inner 

 condyle of the femur is longer, as are also 

 1he inner cartilage and tibial surface; the 

 outer structures are shorter and rounder in 

 shape. The inner condyle exhibits a curve, 

 possibly related to the small amount -of 

 movement it has on the tibia rotating round 

 the femoral attachment of the anterior 

 crucial ligament : no definite corresponding 

 curve is seen on the tibia, but the contiguous 

 margins of the tibial surfaces show a com- 

 parable difference. 



