THE KNEE-JOINT 



289 



horn of the medial semilunar meniscus, and receives a large slip from the lateral meniscus, 

 which ascends along it, either in front or behind, to the femur; higher up in front it is connected 

 with the anterior crucial hgament. 



Until they rise above the intercondyloid eminence of the tibia the two crucial ligaments 

 are closely bound together, so that no interspace exists between their tibial attachments and 

 the point of decussation; the only space between them is therefore a V-shaped one correspond- 

 ing to the upper half of then- x-shaped arrangement, and this is a mere chink in the undissected 

 state, and can be seen from the front only, owing to the fatty tissue beneath the synovial mem- 

 brane which surrounds their femoral attachment. 



The interarticular menisci or semilunar j&bro-eartilages (figs. 319 and 320) 

 are two crescentic discs resting upon the circumferential portions of the articular 

 facets of the tibia, and moving wath the tibia upon the femur. They some- 

 what deepen the tibial articular surfaces, and are dense and compact in structure, 

 becoming looser and more fibrous near their extremities, where they are firmly 

 fixed in front of and behind the intercondyloid eminence of the tibia. The 

 circumferential border of each is convex, thick, and somewhat loosely attached to 

 the borders of the condyles of the tibia by the coronary ligaments and the re- 

 flexion of the synovial membrane. The inner border is concave, thin, and free. 

 Half an inch (1.3 cm.) broad at the widest part, they taper somewhat toward their 



Fig. 320. — Structures lying on the Head of the Tibia. (Right knee.) 



Ligamentum patellae- 

 Expansion from quadriceps 

 femoris tendon 



Transverse ligament 



Lateral meniscus 

 Anterior crucial ligament 

 Medial meniscus 



Posterior crucial ligament 



>r — Tendon of biceps 



Fibular collateral 

 ligament 



extremities, and cover rather less than two-thirds of the articular facets of the 

 tibia. Their upper surfaces are slightly concave, and fit on to the femoral 

 condyles, while the lower are flat and rest on the head of the tibia; both surfaces 

 are smooth and covered by synovial membrane. 



The lateral meniscus (fig. 320) is nearly circular in form and less firmly fixed than the 

 medial, and consequently slides more freely upon the tibia. Its anterior cornu is attached to a 

 narrow depression along the lateral articular facet, just in front of the lateral intercondyloid 

 tubercle of the tibia, close to, and on the lateral side of, the anterior crucial ligament; a small slip 

 from the cornu is often fixed to the tibia in front of the crucial hgament. The posterior 

 cornu is firmly attached to the tibia behind the lateral intercondyloid tubercle, blending with the 

 posterior crucial Ugament, and giving off a weU-marked fasciculus, which runs up along the 

 anterior border of the ligament to be attached to the femur (ligament of Wrisberg). It also 

 sends a narrow sUp into the back part of the anterior crucial hgament. Its outer border is 

 grooved toward its posterior part by the popliteus tendon, which is held to it by fibrous tissue 

 and synovial membrane, and separates it from the fibular collateral Ugament. From its anterior 

 border is given off the transverse ligament. 



The medial meniscus (fig. 320) is a segment of a larger circle than the lateral, and has an 

 outUne more oval than circular. Its anterior cornu is wide, and has a broad and obUque attach- 

 ment to the anterior margin of the head of the tibia. It reaches from the margin of the condyle 

 toward the middle of the fossa in front of the intercondyloid eminence, being altogether in front 

 of the anterior crucial Ugament. The posterior cornu is firmly fixed by a broad insertion in an 

 antero-posterior line along the medial side of the posterior intercondyloid fossa, from the medial 

 tubercle to the posterior margin of the head of the tibia. Its convex border is connected with 

 the tibial collateral Ugament and the semimembranosus tendon. 



The transverse ligament (figs. 319 and 320) is a rounded, slender, short cord, 

 which extends from the convex border of the lateral meniscus to the concave 

 border or anterior cornu of the medial, near which it is sometimes attached to the 

 bone. It is an accessory band of the lateral meniscus, and is situated beneath 

 the synovial membrane. 



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