CHAPTER VIII. 



Tab. XI. — THE HIP, KNEE AND ANKLE JOINTS. 



Fig. 1. The capsular ligament is here opened in order to show the 

 ligament of the hip, named the round ligament. It allows considera- 

 ble latitude of motion, at the same time that it is the great safe-guard 

 against dislocation. 



Fig. 2. and 4. The crucial or internal ligaments of the knee-joint 

 arise from each side of the depression between the condyles of the 

 thigh bone ; the anterior is fixed into the centre, the posterior into 

 the back of the articulation of the tibia. This structure properly Urn- 

 its the motions of the joint, and gives the firmness requisite for violent 

 exertions. Viewing the form of the bones, we should consider it one 

 of the weakest and most superficial, but the strength of its ligaments 

 renders it the most secure, and the least liable to dislocation of any joint 

 in the whole body. 



Fig. 3. One of the interarticular cartilages of the knee, from their 

 shape called semilunar ; it is also represented in situ, Fig. 2. The 

 outer edge of each cartilage is thick, the inner concave edge thin; 

 the sockets for the condyles of the thigh bone are thus rendered deep- 

 er, and the cartilages are so fixed as to allow a little play on the tibia, 

 by which the joint moves with great freedom. 



A moving cartilage is not common, but is peculiar to those joints 

 whose motions are very frequent, or which move under a great 

 weight. It is a contrivance found at the inner head of the collar bone 

 and the articulation of the wrist, as well as at the knee. The obvious 

 use is to lesisen friction and facilitate motion. 



Fig. 4. Exhibits the formation of the ankle joint ; a, the fibula ; b, 

 the tibia. 



