ARTICULATIONS 315 



of the femur, where it is attached. This band is termed 

 the patellar synovial fold (O.T. ligamentum mucosum). As 

 it approaches the femur it becomes narrow and slender ; 

 but, before it fairly rises from the surface of the infra-patellar 

 pad it is broad and triangular, and presents two free margins 

 which extend along the lateral borders of the distal part of 

 the patella, and receive the name of plicae alares (ligamenta 

 alarid). It must be clearly understood that these are not 

 ligaments in the ordinary sense of the word, but merely folds 

 of synovial membrane. 



Within the joint the dissector is now able to recognise : 



1. The two crucial ligaments. 



2. The two menisci (O.T. semilunar cartilages). 



Stratum Synoviale (O.T. Synovial Membrane). As the 



knee-joint is the largest joint in the body its synovial mem- 

 brane is more extensive than that of any other joint. It lines 

 the deep surfaces of the ligamentous structures of the lateral 

 and anterior parts of the joint. It also lines the deep surfaces 

 of the medial and lateral portions of the posterior part of the 

 capsule, and from them it is prolonged anteriorly along the 

 sides and round the front of the crucial ligaments. In the 

 anterior part of the joint it is prolonged proximally beyond 

 the articular surface of the distal end of the femur, in the 

 form of a great cul-de-sac, under cover of the tendon of the 

 quadriceps. The proximal extremity of this cul-de-sac usually 

 communicates by an orifice of greater or less width with the 

 suprapatellar bursa. The synovial membrane also invests the 

 menisci and a pouch-like diverticulum is prolonged posteriorly 

 and distally, along the tendon of the popliteus which it partially 

 ensheaths, across the posterior part of the external border ot 

 the lateral meniscus to the posterior aspect of the proximal 

 end of the tibia. This prolongation lies is close relation with 

 the capsule of the tibio-fibular joint, and in some cases a 

 communication is established between the cavity of the 

 diverticulum and the cavity of the tibio-fibular joint. 



Dissection. Divide the patellar synovial fold and remove the infra- 

 patellar pad of fat. The bursa between the ligamentum patellae and the 

 proximal part of the tuberosity of the tibia may now be opened and 

 examined. Next dissect away the intermediate part of the posterior 

 portion of the capsule (oblique popliteal ligament) and trace the median 

 genicular artery, which pierces it, forwards to the crucial ligaments. 

 It will now be seen that the posterior surface of the posterior crucial 

 ligament is not covered by synovial membrane, and that it is connected 



