754 



LIGAMENTS OF THE KNEE JOINT. 



are very strong, and are relaxed when the leg is bent, but 

 tense when it is extended. 



The semilunar carti- 

 lages (Fig. 246) are sit- 

 uated upon the superior 

 articular surface of the 

 tibia, and are two in 

 number, an external and 

 an internal. The outer 

 edge of each is thick, 

 the inner edge thin, 

 sharp, and loose. The 

 upper surface of each is 

 concave, the lower sur- 

 face flat. The external 

 receives the head of the outer condyle, and is more circular 

 and movable than the internal, which receives the inner con- 

 dyle. The circumference of the semilunar cartilages is 

 attached to the margin before and behind the spine of the 

 tibia, and to the lateral ligaments. These cartilages are 

 connected in front by fibres called the transverse ligament. 

 The synovial membrane is both extensive and complex. 

 It covers the head of the tibia, both surfaces of the semi- 

 lunar cartilages, the condyles of the femur, the inner sur- 

 face of the patella, the crucial ligaments, and posterior 

 surface of the tendons of the recti muscles. It gives off 

 several reflections which have been styled ligaments. The 

 double fold of this membrane upon a quantity of fat behind 



FIG. 246, A represents the Knee Joint laid open. 1 Lower end of femur. 

 2 Anterior crucial ligament. 3 Posterior crucial ligament. 4 Fasciculus 

 attached to semilunar cartilages. 5 Point where ligamentum mucosum is 

 attached. 6 Internal semilunar cartilage. 7 External semilunar cartilage. 

 8 Ligamentum patella. 9 Bursa laid open. 10 Superior peroneo-tibial 

 articulation. 11 Interosseous ligament. 



FIG. 246, B represents a Vertical section of Knee Joint. 1 Cellular struc- 

 ture of lower end of femur. 2 Common tendon of the extensor muscles, at- 

 tached to the patella. 3 Patella. 4 Ligamentum patellae. 5 Cancellated struc- 

 ture of tibia. 6 Bursa between tibia and ligament of patella. 7 Adipose matter 

 projecting into the joint. 8 Synovial membrane. 9 One of the ligamenta alaria. 

 10 Ligamentum mucosum. 11 Anterior crucial ligament. 12 Posterior crucial 

 ligament. 



