ARTICULATIONS OF THE LOWER EXTREMITIES. 307 



on the anterior surface of the tendinous origins of the gastroc- 

 nemius, and envelops the tendon of the popliteus; it also invests 

 the crucial ligaments, but in such a way as to leave them out 

 of its cavity. 



The mass of fat behind the tendon of the patella forms, just 

 below the latter, a ridge on each side, protruding into the arti- 

 culation, and having a fringed summit formed by a doubling of 

 the synovial membrane. The external ridge is the Ligamentum 

 Alare Minus Externum, and the other the Ligamentum Alare 

 Majus Internum. These ridges converge at their lower extre- 

 mities, and from their point of union proceeds a duplicature of 

 the synovial membrane, in front of the anterior crucial ligament; 

 the other end of the duplicature is attached to the posterier ex- 

 tremity of the groove, in the middle of the trochlea, for the pa- 

 tella. This duplicature is the Mucous Ligament, (Ligamentum 

 Mucosum.) 



Of the Peroneo-Tibial Articulation. 



The tibia and fibula are held together by three places of 

 union, one above, another below; and, thirdly, the ligament 

 which fills up the space between the bodies of the bones. 



1. The Superior Articulation, formed by the upper extremity 

 of the fibula and the outer side of the head of the tibia, is entire- 

 ly disconnected with the cavity of the knee joint, and has no- 

 thing in common with its apparatus, except the external lateral 

 ligament, which has been described. The articular faces are 

 small, and covered with cartilage; an anterior and a posterior 

 ligament, and a synovial membrane, hold the bones together at 

 this point. 



The anterior ligament is attached by one end to the front of 

 the head of the fibula, and proceeding upwards and inwards, is 

 inserted by the other into the contiguous part of the head of 

 the tibia, before the articular facet. The fibres are separated 

 into fasciculi, leaving interstices between them for cellular sub- 

 stance. 



The posterior ligament is narrower than the anterior, but its 

 fibres are more compact; and, like the anterior, they observe a 

 transverse course, being attached by the one end to the head of 

 the fibula, and, by the other, to the head of the tibia. The pop- 



