234 SYNOVFAL CAPSULES. 



Of the Synovial Capsules. 



< The synovial capsules are formed of an extremely thin 

 transparent, double reflected tissue, the vessels of which circu- 

 late in the healthy state only the serous portions of the blood, 

 and which, though erected into a distinct tissue or system by 

 Bichat, under the name of synovial, is now generally considered 

 as forming only a part of th general serous tissue, which it 

 closely resembles in structure, and with which it intimately 

 sympathizes in disease. They are of three kinds : 1st. Those 

 which line the inner surface of the ligaments of the joints, and 

 are reflected over the surfaces of the articular cartilages. These 

 are called the articular synovial cartilages. 2d. Those which 

 are placed between the tendons of the muscles, and the bones 

 and cartilages against which the tendons rub. These are called 

 burscE mucoscs. 3d. Those which are placed between the* skin 

 and the bones, tendons, or other hard parts, over which it per- 

 forms frequent and extensive movements. These are called the 

 subcutaneous synovial capsules. 



Of the Articular Synovial Capsules. 



They are invested in a particular manner by a thin delicate 

 membrane, which in some joints, as those of the hip and 

 shoulder, seems to be the internal lamina of a stronger liga- 

 ment called the capsular ; and, in other joints, the knee, for 

 example, appears to be independent of any other structure. 

 In each case, this synovial membrane, as it has lately been 

 called, forms a complete sac or bag which covers the articular 

 surface of one bone, and is reflected from it to the correspond- 

 ing surface of the other ; adhering firmly to each of the 

 articulating surfaces, and extending loosely from the margin of 

 one surface to that of the other. 



In the distribution it supplies the place of perichondrium to 

 the cartilages, and of periosteum to those surfaces of bone with 

 which it is connected. 



It seems greatly to resemble the membranes which line the 



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