341 



by other transverse fibres. This verticle direction of the greatest pan 

 of cartilaginous fibres, demonstrated by Lassone, is very favourable to 

 their elastic re-action. The capsular ligament is reflected over them, be- 

 comes very thin, and is lost in their perichondrium, according to Bonn, 

 Nesbit, and other anatomists. 



Besides the cartilages which surround the extremities of bones, there 

 are found, in certain articulations, fibre-cartilaginous lamina lying be- 

 tween the articulating surfaces. These connecting ligaments may be ob- 

 served in the articulation of the lower jaw to the temporal bones, of the 

 femur with the tibia, and of the sternum with the clavicle ; and all such 

 articulations perform a great number of motions, as is the case with the 

 jaw, or suffer considerable pressure, as the joints of the knee and sternum. 

 The latter, which has a very slight degree of motion, being the point in 

 which terminate all the efforts of the upper extremity, required this ap- 

 paratus to lessen the effect on the trunk, the motion that is given, being 

 in part, lost, in the action of the articulating cartilage*. 



I shall.'not repent what has been already said of the secretion of the fluid 

 that lubricates the articulating surfaces, that facilitates their motion, and 

 keeps them in contact. Its quantity is in direct ratio to the extent of 

 these surfaces, and of the membranous capsule in which they are contain- 

 ed ; it is likewise, proportioned to the frequency of motion which each 

 articulation allows. 



Synovia is the name that is given to the fluid prepared by the glandule- 

 cellular bodies in the vicinity of the articulations, and secreted by the 

 membranous capsules which surround them, and are reflected over the 

 articulating extremities of the bones whose cartilages they cover ; so that, 

 as was shown by Bonn, about the middle of the last century, these extre- 

 mities cannot be said to be contained within the cavity of the capsule, 

 which is closed in every direction, any more than the abdominal viscera 

 within that of the peritoneum. The synovia is heavier than common wa- 

 ter, quite cojourless, and more viscid than any other animal fluid. It 

 contains a considerable quantity of albumine, which, according to Mar- 

 gueron, who first gave a tolerably accurate analysis of synovia, it is found 

 in a particular state, and much disposed to concrete in to filaments, on the 

 addition of acids. 



Besides, it contains muriate and carbonate and phosphate of lime, 

 the whole dissolved in water, which forms about three-fourths of its 

 weightf. 



CLXXIX. Theory of Anchylosis. Motion may be considered as the 

 proper stimulus of the synovial secretion; and a moveable joint, as is just- 

 ly observed by Grimaud,is as a centre of fluxion towards which the fluids 

 rush, in every direction, in consequence of the irritation which friction 

 determines. If the joint remains long without motion, the synovia is se- 

 creted in smaller quantity, and this lessens gradually : it may even hap- 



* The most certain proof of the organic nature of the cartilages is the serous exuda- 

 tion which appears in the course of a few seconds after a clean division of them by the 

 knife. Cellular texture forms the mould or basis in which the cartilaginous substance is 

 deposited. The vessels of this texture carry only the colourless part of the blood into 

 it, during its ordinary state of health; yet it is remarkable that other colouring substan- 

 ces, as bile and madder, give this substance their respective colours Copland. 



| See the Chapter on the Chemical Constitution of the Secretions, &c. at the end of 

 the ApBExmx. Copland. 



