134 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 217. — The right knee-joint in extension seen from in front (§). 

 Fig. 218. — The rijdit knee-joint in extension .seen from behind (§). 



Fig. 219. — The right knee-joint in extension opened by two lateral incisions. The quadriceps muscle, 

 together with the patella, has been reflected downward (§). 



FlG. 220. — The right knee-joint in flexion after removal of the articular capsule and the lateral 

 ligaments (§). 



It is broader than the internal meniscus, and, as its radius is smaller, it covers the condyle of the 

 tibia except in the situation of its relatively small median hiatus. It arises in the anterior intercon- 

 dyloid fossa of the tibia and runs to the external intercondyloid tubercle, while the internal meniscus 

 passes from the anterior margin of the articular surface of the internal condyle to the posterior 

 intercondyloid fossa. The anterior portions of both menisci are connected by fasciculi which vary 

 greatly in their development and are known as the transverse ligament, and their thick external 

 margins are adherent to the articular capsule, the external meniscusbeing less intimately adherent, 

 and hence more movable than the internal one. 



In addition to the menisci, the articular cavity also contains two important accessory liga- 

 ments, the crucial ligaments \ Figs. 220 and 221), of which there are two, an anterior and a posterior. 

 Their anterior surfaces are provided with a synovial covering which passes as a septum through 

 the posterior portion of the articulation, and they are strong ligaments firmly connecting the tibia 

 with the femur. They both arise from the intercondyloid fossa of the femur and pass to the 

 tubercles and intercondyloid fossae of the tibia. The anterior ligament has a broad origin on the 

 inmr surface of the external condyle of the femur, and, becoming narrower, it passes to the anterior 

 intercondyloid fossa and to the anterior intercondyloid tubercle of the tibia. The posterior liga- 

 ment passes from the outer surface of the internal condyle of the femur to the posterior intercon- 

 dyloid fossa and to the corresponding tubercle of the tibia; it is flat at its origin but rounded at its 

 insertion, and is usually Wronger than the anterior ligament. During rest (semiflexion), the two 

 ligaments cross in such a way that the anterior one is in front of the posterior. The latter is usu- 

 ally connected with the external meniscus. 



W ith tlie exception of certain diverticula of the synovial membrane, which will subsequently 

 be described, the articular capsule is attached to the margins of the cartilaginous articular surfa< 

 Its line of attachment upon the posterior surface of the femur is indicated by the intercondyloid 

 line, so that the entire intercondyloid fossa is situated within the articular cavity. 



The knee joint possesses a number of peculiarities; its synovial folds are more pronounced 

 than those of any other joint in the body; its synovial membrane gives off diverticula, some of 

 which are of large size and pass beneath the- neighboring muscles; it is much strengthened by the 

 majority of the overlying tendons; and the patella is embedded in the anterior portion of the 

 articular capsule and forms the- immediate anterior boundary of the articular cavity. 



The majority of the reinforcing ligamentsof the knee joint are adherent to the capsule through- 

 out the greater portion of their extent. There are two lateral ligaments, the fibular and the tibial 

 lateral ligament. The tibial (internal) lateral ligament 1 Figs. 217 and 218) arises from the internal 

 cpicondyle and is intimately adherent to the capsular ligament; its superficial fibers run to the 



