50 ANATOMY FOR NURSES. [CHAP. V. 



The synovial membranes are composed entirely of connective 

 tissue, with the usual cells and fibres of that tissue. They are 

 distinguished by the nature of their secretion, which is a viscid, 

 glairy fluid, resembling the white of an egg and named synovia. 

 From its nature, it is well adapted for diminishing friction, and 

 thereby facilitating motion. 



These membranes are found surrounding and lubricating the 

 cavities of the movable joints in which the opposed surfaces 

 glide on each other ; in these situations they are called articular 

 synovial membranes. They are found forming sheaths for the 

 tendons of some of the joints, and thus facilitating their motion 

 as they glide in the fibrous sheaths which bind them down 

 against the bones; they are here called vaginal synovial mem- 

 branes, or synovial sheaths. Lastly, they are found in the form 

 of simple sacs, interposed, so as to prevent friction, between two 

 surfaces which move upon each other, and in these situations 

 they take the name of bursal synovial membranes, or synovial 

 bursse. These bursso may be either deep seated or subcu- 

 taneous. The former are, for the most part, placed between a 

 muscle and a bone, or between a tendon and a bone. The sub- 

 cutaneous burs86 lie immediately under the skin, and occur in 

 various parts of the body, interposed between the skin and 

 some firm prominence beneath it. The large bursa situated 

 over the patella is a well-known example of this class, but 

 similar, though smaller, bursee are found also over the olecranon, 

 the malleoli, the knuckles, and other prominent parts. 



TABLE OF JOINTS. 



1. Synchondrosis. A thin layer of cartilage is inter- 

 posed between the bones to which it adheres 



closely on each side. 

 SYNARTHROSIS, 



2. Suture. A thin layer of fibrous tissue is inter- 



OR. *s 



T posed between the bones. Sutures may be den- 



IMMOVABLE JOINT. 



tated, tooth-like; serrated, saw-like; squamous, 



scale-like ; harmonic, smooth ; and grooved, for 

 the reception of thin plates of bone. 



1. Symphysis. The bones are united by a plate or 

 disk of fibro-cartilage of considerable thickness; 



AMPHIARTHROSIS, 



OR 



or by articular cartilages lined by a partial syno- 

 vial membrane. 



SLIGHTLY MOVABLE ., . . ,_, , ., , , 



2. Syndesmons. 1 he bony surfaces are united by 



an intrrosscoiis ligament, as in the lower tibio- 

 fibular articulation. 



