218 



DISSECTION OF THE LEG. 



Semilunar 

 cartilages 

 are two. 

 Common 

 characters. 



Internal 

 is oval. 



External 

 nearly cir- 

 cular in 

 form : 



its trans- 

 verse and 



flexion, in which the tibia is being drawn back over the femur. 

 This use will be exemplified by cutting across the posterior (in 

 another joint or in another dissection) and leaving entire the ante- 

 rior ; when this has been done, the articular surfaces of the tibia 

 can be carried nearly altogether behind the condyles of the femur. 



The two inter articular or semilunar jibro-cartilages (fig. 84) partly 

 cover on each side the articular surface of the tibia. 



They are thick at the convex margin, where they are united by 

 fibres to the capsule, and are thin, sharp, and free at the concave 

 edge ; they are hollowed on the upper surface, so as to assist in 



giving depth to the fossae foi- 

 l-he reception of the condyles 

 of the femur, but are flattened 

 below. Inserted into the tibia 

 at their extremities, they are 

 coarsely fibrous at their attach- 

 ment to the bone, like the 

 crucial ligaments ; and they 

 become cartilaginous only 

 where they lie between the 

 articular surfaces. The sy no- 

 vial membrane is reflected over 

 them. 



The internal fibro-cartilage (a) 

 is oval in form, and is less 

 sharply curved than the ex- 

 ternal. In front it is attached 

 by a pointed end close to the 

 anterior margin of the head of 



FIG. 84. THE FIBRO-CAKTILAGES OF 

 THE KNEE-JOINT. \ 7 mv OF THE 

 HKAD OF THE TIBIA WITH THE 

 FlBRO-CARTILAGES ATTACHED ; THE 

 CRUCIAL LIGAMENTS HAVE BEEN CUT 



THROUGH. 



a. Inner, and b, outer semilunar 

 nbro-cartilage. 



c. Transverse, and d, ascending or 

 posterior band (cut) of the external 

 cartilage. 



e. Posterior, and _/, anterior crucial 

 ligament. 



the tibia, in front of the anterior 

 crucial ligament. At the back, 

 where it is much wider, it is 

 fixed to the inner lip of the 

 hollow behind the spine of the 

 tibia, between the attachment 

 of the other cartilage and the posterior crucial ligament. 



The external fibro-cartilage (b) is nearly circular in form, and is 

 connected to the bone within the points of attachment of its fellow. 

 Its anterior part is fixed in front of the spine of the tibia, close to 

 the outer articular surface, and opposite the anterior crucial ligament 

 which it touches ; and its posterior extremity is inserted behind and 

 between the two osseous points of the spine. This fibro-cartilage is 

 less closely united to the capsule than the internal, for the fore part 

 is in the centre of the joint, and the tendon of the popliteus muscle 

 separates it behind from that membrane. 



The outer fibre-cartilage is provided with two accessory bands, 

 one in front, the other behind. 



The anterior or transverse ligament (c) is a narrow band of fibres 

 between the semilunar cartilages at the front of the joint. Some- 

 times it is very small or even absent. 



