SECT. 95.] 



OSSEOUS SYSTEM. 



l8l 



substance, so that ulcerous breaches are formed, which may pe- 

 netrate to the bone, or proceed from it. 



§ 95. The articular capsules are not shut sacs, but short and 

 wide tubes, which arc applied with their two open ends to the 

 borders of the articular surfaces of the bones, and connect them. 

 The articular capsule is, in some cases, attached simply to the 

 border of the cartilaginous surface, and thence passes directly to 

 the other bone (patella, am phi arthroses) ; in other cases, it also 

 covers a greater or less part of the bone adjoining the cartilaginous 

 surface, and is then reflected, in order to become connected with 

 the other bone, in one of these two modes. In neither case docs 

 the synovial membrane rest immediately upon the hard structure, 

 but is more or less closely adherent to the periosteum, and, finally, 

 terminates, without a well-defined edge, not far from the border of 

 the articular cartilage, with the perichondrium of which it is in- 

 separably united. In point of intimate structure, the outer fibrous 

 capsules entirely agree with the fibrous ligaments, whilst the 

 synovial membranes consist 1. : of a layer of Kg. 83. 



connective tissue with fine elastic fibres, and 

 not very numerous vessels and nerves ; and 

 2. of an epithelium composed of one to four 

 layers of flattened cells, of 0*005"' to o - oo8'" 

 in diameter, with rounded, nuclei. These 

 membranes do not possess glands and pa- 

 pilla^ but they include in their folds large 

 collections of fat (plicce adiposes.), and are 

 furnished with vascular processes (plica vas- 

 culosce), or synovial fringes. The former, at 

 one time improperly called Haversian glands, 

 principallv occur in the hip and knee ioints Diagrammatic view of a sec- 



. /» n li *' 10n °^ a finger-joint, in part 



in the form of yellow, or yellowish-red, soft aftor Arnold. «. Bones ; &. arti- 



-* . i^i cular cartilages ; c. periosteum 



processes Or folds, and COllSlst merely Of large passing into the perichondrium 



... . „ n • "t of the articular cartilages; d. 



Collections OI fat- Cells 111 more VaSCUlar parts synovial membrane at the 



c , . , , mi i  border of the cartilage, begin- 



ot the synovial membrane. The latter exist ing to become connected with 



, ,, . . . -, n - the perichondrium; e. epithe- 



m almost all joints ; they are small flattened hum of the same. 

 projections of the synovial membrane, of a red colour (if their 

 vessels are full) indented and plaited at their borders, and beset 

 with smaller processes. They are generally situated near to where 

 the synovial membrane arises from the cartilage, and lie flat upon 

 it, so that they often form a sort of wreath around it ; in other 

 cases they are more isolated, aud also occur in other parts of the 



