170 



ARTICULATIONS OF THE LO^YEE LIMB. 



of the patella and the femur it consists of fibres connected witli the 

 insertion of the yasti muscles and with the fascia lata, and thus forms 

 the structures, uniting the patella to the tibia, -which have been called 

 ]((ieral palellar ligaments; posteriorly it covers the condyles of the 

 femur beneath the gastrocnemius muscle. In this last situation it is 

 thin, and a sesamoid bone is often found in connection with it in the 

 outer, less frequently in the inner head of the muscle. 



The synovial membrane is the largest in the body. Traced down- 

 wards from the femur on either side of the joint, it may be followed 

 from the capsule to tiie upper surface of the semilunar cartilages, round 

 the free borders of those structures to their inferior surfaces, and thence 

 to the tibia. The crucial hgameuts are invested in front by a reflected 



Fig. 152. — VEniic.iL Antero-Fosterior Section 

 OF THE Left Knee-Joint, seen froji tue 



OUTER. OR LEFT SIDE. (A. T. ) ^ 



The section is made somewhat obliquely a little 

 to the outside of the middle, so as to preserve entire 

 the crucial ligaments with their attachments : it is 

 from a young subject of eighteen or nineteen years. 

 1,1, the upper portion of the synovial cavity ex- 

 tending upwards between the extensor tendons arid 

 the femur ; 1', an apertui-e made into the posterior 

 l^ortion of the synovial cavity ; 2, 2', ligamentum 

 mucosum ; 3, ligamentum patellte ; 2', 3, the sub- 

 patellar synovial fatty cushion ; 4, bursa above the 

 insertion of the ligamentum patelhe into the ante- 

 rior tibial tulierosity ; 5, 5', the anterior crucial 

 ligament ; 5', points also to the internal semilunar 

 cartilage within the joint ; (J, lower part of the 

 posterior crucial ligament, the upper part of which 

 is towards 2 ; 6', the accessory band joining the 

 external semilunar cartilage, which is cut short ; 

 7, the spine of the tibia. 



portion of the membrane continued for- 

 Avards from the posterior wall of the joint. 

 Between the tibia and patella the syno- 

 vial membrane lies upon a large pad or 

 cushion of fat. on the surface of which 

 it forms two lateral folds {alar ligamcnis) 

 Avhich fit into the space between the 

 tibia, patella and femur, while from the 

 middle of the pad it sends backwards 

 a tapering process, the ligamentum mucosum, through the joint to the 

 front of the intercondylar fossa. Above the patella the synovial mem- 

 brane extends upwards some distance, forming a large pouch between 

 the extensor tendons and the femur. 



Movements, &c. — In order to explain the nature of the movements, it is 

 necessary to state ■■^ome considerations with regard to the relations of the several 

 parts of the knee-joint to each other. The knee-joint may be regarded as con- 

 sisting of three articulations conjoined, viz.. that between the patella and femur, 

 and two others, one between each condyle of the femiu- and the tibia. In most 

 mammals the synovial membranes of those three joints are either completely 

 distinct or communicate with each other hj only small oijenings ; and this some- 

 times occui's in Man. In the human subject the ligamentum mucosum is an 



