320 INFERIOR EXTREMITY 



anterior portion of the lateral surface of the medial condyle. 

 It receives one, or sometimes two, strong slips from the 

 posterior horn of the lateral meniscus (Fig. 118, p. 319). 



The anterior crucial ligament is tight in extension, and 

 the posterior crucial ligament is tight in flexion of the knee- 

 joint. 



Menisci (O.T. Semilunar Cartilages). These are two cres- 

 centic plates of fibre-cartilage which are placed on the condylar 

 surfaces of the tibia. They deepen the surfaces upon which 

 the condyles of the femur roll, and, being movable, they fill up 

 the gaps which would otherwise arise during the movements 

 of the joint. Each meniscus presents two fibrous extremities, 

 or horns, which are attached to the rough intermediate surface 

 on the proximal end of the tibia. They are thick towards the 

 circumference of the joint, but thin away to a fine free 

 concave edge in the opposite direction. Both surfaces are 

 smooth and covered with synovial membrane. They do not 

 cover the entire extent of the condylar surfaces of the tibia. 

 The central parts of the latter, as well as the sloping surfaces 

 of the tubercles of the eminentia intercondyloidea, are free. 

 On raising the cartilages from the surface upon which they 

 rest, distinct impressions similar in shape and extent are seen 

 on the subjacent encrusting cartilage of the tibia. 



Dissection. Carefully define the attachments of the fibrous horns of the 

 menisci. 



The lateral meniscus is usually somewhat thicker around 

 its circumference than the medial meniscus. It forms the 

 segment of a smaller circle, and its horns being fixed to the 

 tibia close together, a very nearly complete circle is formed. 

 The anterior fibrous horn is attached, immediately in front of 

 the intercondylar eminence, to the lateral side of and partly 

 under cover of the attachment of the anterior crucial ligament. 

 The posterior horn is fixed to the summit of the inter- 

 condylar eminence in the interval between the two tubercles. 

 It likewise gives a strong slip to the posterior crucial ligament. 

 The fibular collateral ligament is not in contact with the 

 lateral meniscus. It is separated from it by the tendon of 

 the popliteus, and the impress of the tendon is left on the 

 cartilage in the form of a faint smooth groove on the 

 posterior part of its lateral border. Posteriorly, its circumfer- 

 ence is attached to the posterior ligament. 



