42 ANTHROPOLOGY. 



dyles of the femur, the head of the tibia, and the patella, enter into this 

 articulation ; the fibula is only remotely connected with it. The ligaments 

 which secure it may be classed into those external and those internal to the 

 synovial membrane. The external ligaments are the ligamentum patella', 

 ligameyitum posticum, and the internal and external lateral ligaments. The 

 internal are the two crucial, the inter-articular fibro-cartilages, the trans- 

 verse, and certain folds of the synovial membrance. 



The ligamentum imtelhn {pi. 126, fig. 8''") consists of strong, parallel, 

 glistening, tendinous fibres which arise from the inferior angle and from the 

 anterior surface of the patella, and are inserted into the tubercles of the 

 tibia. This ligament is principally a continuation of the extensor tendon, in 

 which the patella was developed first in the form of a cartilage. 



The posterior ligament arises from the tendon of the semi-membranous 

 muscle, and ascends obliquely from behind the inner condyle of the tibia to 

 the external condyle of the femur. 



The internal lateral ligament {figs. 8\ 9°) arises from the back part of the 

 tuberosity on the inner condyle of the femur, below the insertion of the 

 tendon of the abductor magnus ; descends obliquely forwards, and is inserted 

 into the internal condyle of the tibia. 



The external lateral ligament {figs. 8\ 9 ') arises from the back part of the 

 tuberosity on the external condyle, above the fossa for the poplitaeal tendon ; 

 it is thick, round, and smooth ; descending, it is inserted into the outer side 

 of the head of the fibula. 



The synovial membrane of the knee is the largest of its class in the 

 body. 



The internal ligaments in the knee joint are the alar, mucous, transverse, 

 crucial, and semi-lunar cartilages. 



The alar ligaments {fig. 8 ') are only folds of the synovial membrane, in 

 some measure produced by the displacement and eversion of the patella. 

 They are one on each side of the bone, the internal being the most distinct. 



The ligamentum mucosum or adiposum {fig. 11'''') is only a small fl)ld or 

 tubular process of the same membrane : of a conical form, it arises broad 

 from the fatty substance behind the ligamentum patellae, passes backwards 

 and upwards, and is inserted into the notch between the cond^des. The 

 transverse ligament extends between, and is attached to the anterior convex 

 portions of the two semi-lunar cartilages above the articular fatty mass. 



The crucial ligaments {fig. 10"'') are the most important of the inter- 

 articular cartilages. They are two strong, twisted, fibrous cords, which pass 

 from the notch in the femur to the median line of the head of the tibia. 

 They cross each other in passing to their respective attachments, this decus- 

 sation resembling the letter X, whether viewed laterally or before or behind. 

 They serve to attach the femur to the tibia, to steady one bone on the other, 

 and to prevent any lateral displacement. 



The semi-lunar cartilages {figs. 11 ''■*, 10''') are placed upon the articular 



surfaces of the tibia. The convex margin of each is thick, and connected 



by its edges with the synovial membrane, and between these with the 



external ligaments and fascia. The anterior and posterior extremities of 



748 



