118 OF BURSiE MUCOSAE. 



sciatic ligament ; 2, spliinctor ani ; 3, depressor coccy- 

 gis ; 4, the muscles of the tail ; 5, 5, the triceps abductor 

 tibialis ; 6, the vastus externus ; 7, the rectus ; 8, the 

 gastrocnemius muscles ; 9, the plantarius ; 10, the extensor 

 pedis; 11, the peroneus ; 12, the flexor pedis perforans ; 

 13, the insertion of the gracilis; 14, the gastrocnemii 

 muscles; 15, the flexor pedis accessorius ; 16, the course 

 of the perforans tendon, inside the os calcis of the hock 

 joint ; 17, the insertion of the gastrocnemius externus into 

 the point of the hock ; 18, 18, the popliteus muscles ; 19, 

 the extensor pedis. 



SECTION X. 



OF BURS^ MUCOSA, 



Tendons of great length are usually furnished with sheaths, 

 within which is secreted a glairy, slippery fluid, of a similar 

 nature with synovia ; by means of this they are enabled to 

 slide over the bones, or other structures, with great ease. 

 At the extremities of the tendons ; also between them and 

 at the points of bone ; wherever the parts are liable to 

 pressure or friction, these little bladders or sacs, filled with 

 synovia, form distinct structures ; they are called ynucous 

 capsules or hurs(S mucosa;, being composed of dense cellular 

 tissue, whose internal vascular surface is lined by a synovial 

 membrane. From injury, or other causes, this membrane 

 becomes at times inflamed ; and, when resolution of such 

 inflammation is not effected, coagulable lymph is thrown 

 out; which not being always again absorbed, remains between 

 the tendons and its sheath ; occasioning distention and 

 often lameness, from the obstruction it offers to the freedom 

 of motion ; therefore, we are at no loss to account for the 

 gorged sinews in hard-worked horses ; nor for the stiffness 

 they occasion. The mucous capsules, at the extremities of 

 the tendons, also are extremely liable to become distended ; 

 and bursal disease receives very different names according 

 to its situation ; as ivindgalls at the fetlock ; thoroughpin be- 

 hind the hock ; and capped hock at the point of the joint. 

 These diseased accumulations appear to be brought on by 

 undue exertion of the parts : after which, any motion appears 



