IXTEEIOH OF THE KXEE-JOIXT. 169 



tached inferiorly to the back of the pit behind the tibial spine, and 

 superiorly to_,.tlie._fore part of the intercondylar hollow, as well as 

 slic^htly to the side of the inner condyle of the femur ; its fibres are 

 directed upwards and a little forwards. 



The semilvmar cartilages are two crescent-shaped interarticular fibro- 

 cartilao-es, placed on the articulating surfaces of the head of the til^a, 

 and interposed between these and the condyles of the femur. They 

 have each a synovial 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 border 

 of each cartilage is left uncovered. At their extremities they are 

 fibrous, and are firmly fixed to the head of the tibia, whilst by the cir- 

 cumference they are connected with the fibrous capsule of the joint. 



Fig. 151. — View of the Interarticular Fibro- 

 Cartilages op the right Knee-Joint, from 



ABOVE, WITH THE CrUCIAL LiGAJIENTS DIVIDED, 

 AND THE LiGAlIENTUM PaTELL^ TURNED FOR- 

 /WARDS. (A. T). ^ 



1, ligamentum patellaa ; 2, the inner fil)ro- 

 cartilage ; 3, the outer one ; 4, the anterior tuber- 

 osity of the tibia in front of the transverse liga- 

 ment ; 5, the cut end of tlie anterior cnicial liga- 

 ment directed obliquely towards the outer side and 

 backwards ; 6, the ciit end of the iiosterior crucial 

 ligameut, from which fibres are seen descending to 



the outer fibro-cartilage ; 6', tibial attachment of the posterior crucial ligament ; 7, the 

 head of the fibula ; S, the synovial suriiice of tlie tibia, which extends for some way 

 downwards towards the tibio-fibular synovial sac, with which it is sometimes continuous. 



Tlie internal semilunar cartilage forms nearly a semicircle ; 

 its anterior cornu is small and pointed, and is inserted into an impres- 

 sion at the fore and outer part of the internal articular surface of the 

 tibia ; its posterior end is attached to the inner edge of the hollow 

 behind the spine, and is in relation with the posterior crucial liga- 

 ment. 



The external semilunar cartilage forms more than three-fourths of 

 a circle ; its two cornua, fixed, one before, the other between the points of 

 the spine of the tibia, are so close at their insertion that they may be said 

 to be interposed between the attachments of the internal semilunar 

 plate. Its external border is in contact behind with the tendon of the 

 popliteus muscle, and is therefore separated by this fi'om the fibrous 

 capsule. From this fibro-cartilage a ligamentous band ascends, to be 

 attached to the inner condyle of the femur in connection either in front 

 or behind with the posterior crucial ligament {accessory hand of the 

 2Wsf('rior crucial lit/anicnf). 



Transverse ligament. — Towards the front of the joint the convex 

 borders of the interarticular fibro-cartilages are connected by a slight 

 transverse band, which receives this name. Its thickness varies much 

 in difixirent bodies. 



Capsular membrane. — Under this name is described the fibrous 

 tissue which invests the joint in the intervals between the stronger 

 bauds which have been named ligaments. It is incomplete, not extend- 

 ing underneath the tendons of the extensor muscles. Between the sides 



