274 WINDGALL. 



as .that of the joint, and secluded through the density of its parietes 

 from all around, appears requisite, not merely that it may retain 

 the fluid secreted into it, but that no other fluid, not even air, may 

 gain admission into it: the presence of air being found, the same 

 as in joints, to derange its secretory function, and create inflam- 

 mation. Hence it is that an opened bursa or tendinous sheath 

 is regarded in much the same light as an opened joint, or, at all 

 events, as a case calling for more medical skill and attention than 

 any flesh or skin wound of the ordinary description. 



Bursal and Thecal Structures, being appendages to the 

 locomotive apparatus, are regulated in their number and distribu- 

 tion by the amount or extent of motion particular parts of the body 

 possess. This accounts for the bursae and sheaths of tendons 

 being met with exclusively in the limbs ; also for those in the horse, 

 in particular, as an animal forced into speed and labour under 

 heavy burthens, coming so frequently under our notice in states of 

 derangement or disease : the form such deranged or morbid con- 

 dition assumes being usually that of, what is called, 



WINDGALL. 



Such an appellation naturally leads any body to suppose that 

 " wind" must constitute the swelling known as windgall; whereas, 

 in point of fact, it is a bursa filled to distention (not with windj 

 but) with the same kind of synovial fluid of which it contains, for 

 the due performance of its function, but a comparatively small 

 proportion in a state of health. 



The Synovial (and Bursal) Membranes in Disease exhi- 

 bit phenomena analogous to those of their correlative tissues, the 

 serous membranes. Under inflammation — or under even simply 

 increased vascular action — we know how prone the serous surfaces 

 are to emit serous fluid in unnatural quantity, and coagulated 

 lymph along with it. The same propensity brought into action 

 by similar causes is manifested by the synovial and bursal mem- 

 branes. But the synovial is not equally disposed with the serous 

 structure to run into the adhesive inflammation. Effusion of lymph 

 does occur, but not so often, in joints and bursae. Rheumatic in- 

 flammation of joints is one example of it; the intense inflammation 



