16S GENERAL ANATOMY. 



disposition joined to the presence of sheaths; lastly, besides this 

 latter, folds formed by parts which extend into the articulation, 

 and that are covered by the membrane. All these forms, which 

 are so various, are to be referred finally to the vesicular form. 

 214. The external surface of the synovial membranes is 

 more or less intimately connected with the neighbouring 

 parts. They all adhere closely to the articulating surfaces of 

 the bones, or rather to the cartilages which invest them, by 

 the two extremities of the kind of sac they represent. Their 

 connexion with these cartilages is so close as to occasion a 

 belief that the latter is naked: Nesbit, Bonn and W. Hunter, 

 however, long ago announced the existence of a prolongation 

 of the synovial membranes, upon the articulating surfaces of 

 the bones. It is to Bichat in particular, that we are indebted 

 for having, incontestably, established this truth. Some au- 

 thors, however, such as Gordon and M. Magendie, still raise 

 doubts on the subject. Many facts demonstrate the presence 

 of the synovial membranes on the cartilages. When these 

 membranes are inflamed, their redness, which in time becomes 

 apparent, extend around the circumference of the cartilage, 

 and becomes less and less sensible as it advances towards its 

 centre, the membrane becoming more and more identified 

 with the cartilage; the centre itself is finally penetrated with 

 vessels, but the cartilage is coloured only at its surface, pre- 

 serving in its thickness the whiteness peculiar to it. The 

 bridles which are sometimes formed in the synovial mem- 

 branes arise, indifferently, from all parts of their extent, and 

 it is observed that when they adhere to the cartilage, their 

 bases are less closely united to it, and that in this place, the 

 membrane becomes apparent as it naturally is about the arti- 

 culating surfaces: in this manner, the synovial membrane 

 becomes apparent even on the centre of the cartilage. The 

 fungous degeneration peculiar to the synovial membrane is 

 also to be found on the cartilage. Finally direct inspection 

 demonstrates the continuity of this membrane. By obliquely 

 raising a slice of cartilage, and afterwards bending it back so 

 as to break it at its base, it still holds by the synovial mem- 

 brane which covers it equally with the rest of the cartilage. 



