THE KNEE-JOINT. 



185 



wards, and outwards. The posterior or internal ligament, stronger but shorter than 

 the anterior, is attached below to the floor of the popliteal notch of the tibia, and 

 above to the lower part of the outer surface of the internal condyle, as well as to the 

 adjacent fore part of the intercondylar fossa of the femur ; its fibres are directed 

 upwards and a little forwards and inwards. 



The semilunar fibro -cartilages are two crescent-shaped plates, placed on 

 the articulating surfaces of the head of the tibia, and interposed between these 

 and the condyles of the femur. They have each a smooth free surface above 

 and below, and a convex border, which is thick, while the concave border is thinned 

 to a fine edge ; and the part of the articular surface of the tibia within the concave 



Fig. 209, A. THE KNEE-JOINT, OPENED FROM BEFORE, TO SHOW THE CRUCIAL LIGAMENTS AND 

 SEMILUNAR FiBRo-CARTiLAGES. (Allen Thomson.) I 



1, external, 2, internal semilunar fibre-cartilage ; 3, on the outer condyle of the femur, points to 

 the anterior crucial ligament ; 4, placed on the line separating the patellar surface from the inner 

 condylar surface of the femur, points to the posterior crucial ligament ; 5, transverse ligament of the 

 semilunar fibre-cartilages ; 6, part of the ligamentum patellae ; 7, on the head of the fibula, points to 

 the anterior superior tibio-fibular ligament ; 8, upper part of the interosseous membrane, showing the 

 perforation for the anterior tibial vessels. 



Fig. 209, B. THE KNEE-JOINT, OPENED FROM BEHIND, so AS TO EXPOSE THE CRUCIAL LIGAMENTS 



AND SEMILUNAR FIBRO-CARTILAGES. (Allen Thomson. ) | 



1, internal, 2, external semilunar fibro-cartilage ; 3, anterior, 4, posterior crucial ligament ; 

 farther up is seen the accessory band from the external semilunar fibro-cartilage ; 8, upper part of the 

 interosseous membrane ; 9, internal lateral ligament ; 10, placed on the head of the fibula, points to 

 the posterior superior tibio-fibular ligament ; between the head of the fibula and the external fibro- 

 cartilage (2) is seen the surface of the tibia upon which the semilunar cartilage descends in flexion, and 

 where a communication sometimes takes place between the synovial cavities of the knee-joint and of the 

 tibio-fibular articulation. 



border of each cartilage is left uncovered. At their extremities they are fibrous, and 

 are firmly fixed to the head of the tibia, while by their circumference they are 

 connected with the fibrous capsule of the joint. 



The internal semilunar fibro-cartilage forms about a semicircle ; its anterior 

 extremity is small and pointed, and is inserted into an impression at the fore and 

 inner part of the hollow before the spine of the tibia ; its posterior end is attached 



