PLATE IV. 



INFLAMED AND ULCERATED CONDITION OF THE SYNOVIAL 



SURFACES OF THE ASTRAGALUS AND TIBIA 



IN INVETERATE SPAVIN. 



(G 4, Troop Horse, Case related at pages 77-8.) 



Fig, 1, The astragalus presenting to view its articulatory trochleae. 



Fig. 2, The lower end of the tibia presenting its concavities, in which the trochleae 

 of the astragalus play, in the motion of the hock-joint. 



In both bones the synovial membrane upon the articular cartilages is in an 

 inflamed condition, and, especially, shews inflammation around the lips of the 

 ulcerations apparent in the centres of the joint, such parts being deeply red- 

 dened, as well as perceptibly tumefied. 



The caries, or ulcerations, are, in the sites in which they are ordinarily found, 

 viz. in the centre of the articulatory channel between the condyles of the astra- 

 galus, and upon the middle articulatory eminence of the tibia. They are deep 

 and ragged, and in their greatest depths display the bare substance of the 

 cartilage underneath; while around these bare (white) parts granulations are 

 apparent. Altogether, the disease within the joint had the appearance of being 

 of an acute and highly painful character. 



