KNEE-JOINT. 



303 



Fig. 208. Right Knee-joint. Showing 

 ternal Ligaments. 



In- 



the fascia lata, from the Vasti and Crureus muscles, and from the Biceps, Sar- 

 torius, and tendon of the Semi-membranosus. 



The Crucial Ligaments are two interosseous ligaments of considerable strength, 

 situated 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 re- 

 ceived the names anterior and posterior, 

 from the position of their attachment 

 to the tibia. 



The anterior or external crucial liga- 

 ment (Fig. 208), smaller than the pos- 

 terior, is attached to the inner side of 

 the depression in front of the spine of 

 the tibia, being blended with the an- 

 terior extremity of the external semi- 

 lunar fibro-cartilage, and passing ob- 

 liquely upwards, backwards, and out- 

 wards, is inserted into the inner and 

 back part of the outer condyle of the 

 femur. 



The posterior or internal crucial liga- 

 ment is larger in size, but less oblique 

 in its direction than the anterior. It is 

 attached to the back part of the depres- 

 sion behind the spine of the tibia, and 

 to the posterior extremity of the exter- 

 nal semilunar fibro-cartilage; and passes 

 upwards, forwards, and inwards, to be 

 inserted into the outer and fore-part of 

 the inner condyle of the femur. As it 

 crosses the anterior crucial ligament, a 

 fasciculus 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 ligamentum posticum Winslowii. 



The Semilunar Fibro-car- 



tilages (Fig 209) are two Fig. 209. Head of Tibia, with Semilunar Cartilages, etc. 

 crescentic lamellae, which Seen from above. Right Side. 



are attached to the margins 

 of the head of the tibia, and 

 serve to deepen its surface 

 for articulation with the 

 condyles of the femur. The 

 circumference of each car- 

 tilage is thick and convex ; 

 the inner free border, thin, 

 and concave. 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 cartilage covers nearly the outer two-thirds of the corresponding articular 

 surface of the tibia, leaving the inner third uncovered ; both surfaces are 

 smooth, and invested by synovial membrane. 



The Internal Semilunar Fibro-cartilage is nearly semicircular in form, a little 



