THE ARTICULATIONS IN GENERAL. 



171 



In the third, they are amphiarthroses, or mixed articulations; so termed 

 because they participate in the movements of the other two classes : synarthroses, 

 by the continuity established between the articular surfaces ; and diarthroses. by 

 the extensive motion they permit. 



The general characters that distinguish each of these three great classes ol 

 articulations will be successively studied. 



Fia 115. 



PLANS OF THE DIFFERENT CLASSES OF ARTICULATIONS. 



♦, Suture: 1, periosteum ; 2, sutural ligament. B, Amphiarthrosis : a, first degree — 1, periosteum ; 

 2, articular cartilage ; 3, iQterarticular ligament : h, second degree — 4, single cavity in the 

 interarticular ligament : c, third degree — 5, double cavity in the interarticular ligament. C, 

 Diarthrosis : 6, simple diarthrosis — 1, periosteum; 2, articular cartilage,* 3, epithelial layer of 

 the synovial membrane (dotted line) ; 4, fibrous capsule ; 5, cul-de-sac of the synovial membrane ; 

 6, fibrous layer of the synovial membrane : c, double diarthrosis — 7, interarticular meniscus ; 8, 

 9, cavities of the two synovial membranes. 



General Characters of Diarthroses. 



We ought to consider, in the diarthrodial articulations (Fig. 115, c, J and c) : 

 1. The contiguous hony surfaces which form them. 2. The cartilaginous layers 

 {cartUages of incrustatioyi) which cover these. 3. The fibrous or fibro-cartilagi- 

 nous tissue {articular fibro-cartilages) which complete them, when they are not 

 shaped so as to be reciprocally adapted to each other. 4. The ligaments which 



