THE OSSEOUS SYSTEM. 



327 



connective tissue, with occasional cartilage-cells, and an epithe- 

 lium, very thick in places. The smaller ones frequently consist 

 even of nothing but epi- Fig. 127. 



thelium, or of little else 

 than connective tissue. 



In many joints there 

 are firm, whitish-yellow 

 fibrous plates, the so- 

 termed interarticular car- 

 tilages orligaments which, 

 either projecting in pairs 

 from the synovial cap- 

 sule, are interposed be- 

 tween the bones consti- 

 tuting the articulation 

 (knee), or form a single 



diaphragm transversely ^-4tL.^ 



across the joint (articu- 

 lations of the jaw, clavi- 

 cle, sternum, and wrist). 

 These processes consist 

 of a firm, fibrous tissue, the fibres of which, usually cross 

 each other in various directions, and are in all respects 

 closely allied to connective tissue, but presenting less distinct 

 fibrils ; and besides this, of cartilage-cells and fine elastic 

 fibres. The cartilage-cells, in the most superficial layers, 

 are more solitary, in the deeper, disposed more in roivs and 

 smaller, ultimately being replaced by fine elastic fibres, a 

 certain number of which, at all events, appear to originate 

 from cells resembling the cartilage-cells. The interarticular 

 ligaments, which, from what has been said respecting them, 

 must be enumerated among the fibro-cartilages, are not covered 

 by synovial membrane, though they probably have an epithelial 

 investment at the attached border, but onlv for a small 



Fig. 127. From the synovial membrane of a phalangeal articulation : A, two non- 

 vascular appendages of the synovial processes, x 250 diam.; a, connective tissue in 

 its axis; b, epithelium (in the peduncle of the larger process not distinctly cellular) 

 continuous with that on the free borders of the process ; c, d, cartilage cells : B, four 

 culls from the epithelium of the synovial membrane of the knee, one with two nuclei, 

 x 330 diam. 



