370 



THE ARTICULATIONS. 



Femur. 



in the interior of the joint, nearer its posterior than its anterior part. They are 

 called crucial because they cross each other somewhat like the lines of the letter 



X ; and have received the names anterior 

 and posterior, from the position of their 

 attachment to the tibia. 



The Anterior, or External Crucial Liga- 

 ment (Fig. 259), is attached to the depres- 

 sion in front of the spine of the tibia, being 

 blended with the anterior extremity of the 

 external semilunar fibro-cartilage, and, pass- 

 ing obliquely upward, backward, and out- 

 ward, is inserted into the inner and back 

 part of the outer condyle of the femur. Its 

 direction is upward, backward, and outward. 

 The Posterior, or Internal Crucial Lig- 

 ament, is stronger, but shorter and less ob- 

 lique in its direction, than the anterior. It 

 is attached to the back part of the depres- 

 sion behind the spine of the tibia, to the 

 popliteal notch, and to the posterior extrem- 

 ity of the external semilunar fibro-cartilage ; 

 and passes upward, and somewhat forward, 

 and inward, to be inserted into the outer part 

 of the inner condyle of the femur. As it 

 crosses the anterior crucial ligament a fas- 

 ciculus is given off from it, which blends with 

 the posterior part of that ligament. It is 

 in relation, in front, with the anterior 

 crucial ligament; behind, with the capsular 

 ligament. 



The Semilunar Fibro-cartilages (Fig. 260) 

 are two crescentic lamellae which serve to 

 deepen the surface of the head of the tibia, for articulation with the condyles of 

 the femur. The circumference of each cartilage is thick, convex, and attached to 

 the inside of the capsule of the knee ; the inner border is thin, concave and 



free. Their upper surfaces 

 are concave, and in relation 

 with the condyles of the 

 femur ; their lower surfaces 

 are flat, and rest upon the 

 head of the tibia. Each car- 

 tilage covers nearly the outer 

 tAvo-thirds of the correspond- 

 ing articular surface of the 

 tibia, leaving the inner third 

 uncovered ; both surfaces are 

 smooth and invested by syno- 

 vial membrane. 



The Internal Semilunar 

 Fibro-cartilage is nearly sem- 



Fio.260. Head of tibia, with semilunar cartilages, etc. Seen from i circular in form a little 

 above. Right side. ' , . 



elongated irom betore back- 

 ward, and broader behind than in front ; its anterior extremity, thin and pointed, 

 is attached to a depression on the anterior margin of the head of the tibia, in 

 front of the anterior crucial ligament ; its posterior extremity is attached to the 

 depression behind the spine, between the attachments of the external semilunar 

 fibro-cartilage and the posterior crucial ligaments. 



FIG. 259. Right knee-joint. Showing inter 

 nal ligaments. 



