DISEASES OF THE FACIAL SINUSES. 517 



DISEASES OF THE FACIAL SINUSES. 



Tlie facio-cranial sinuses may very reasonably be looked upon 

 as one cavity, divided into frontal, maxillary, and sphenoidal 

 compartments. They form air-cavities, communicating with the 

 nasal passages by a small passage guarded by an imperfect valve. 

 In addition to the above divisions, each compartment is divided 

 into smaller cavities by thin osseous plates, the whole being 

 lined by a continuation of the Schneiderian membrane, which is 

 neither so vascular nor so thick as in the nasal passages. These 

 cavities differ in size in different breeds, as well as in individual 

 horses of the same breed. They are small and ill-developed in 

 all young animals, but rapidly increase in size till full growth is 

 attained. In the ox and sheep they communicate with the canals 

 and foramina of the " horn processes" of the frontal bones ; hence, 

 in the malignant catarrhal fever of the ox the horns are loosened 

 by the extensive suppurative inflammation extending to the 

 cavities of the " horn flint." 



In catarrhal affections, the lining membrane of these sinuses, 

 by extension of the inflammation of the Schneiderian membrane, 

 becomes diseased, and pours out a quantity of pus, which, lodging 

 in the various compartments of the sinuses, becomes a source of 

 irritation, constituting what is known as " nasal gleet " or ozoena. 

 A collection of pus or tumours in the sinuses, if exit be not 

 allowed, cause absorption of the bony plates by pressure. 



Nasal gleet may arise from other causes than catarrhal inflam- 

 mation (but this is the most common cause), such as external 

 injuries, caries of the upper molars, disease of the superior 

 maxilla from elongated inferior molar teeth, alveolar abscesses, 

 hypertrophy of the fangs of the^ teeth, disease of the facial 

 bones, collections of inspissated pus in the convolutions of the 

 ethmoidal and turbinated bones, formation of cystic tumours and of 

 calcareous concretions in the superior maxillary sinuses, and from 

 clots of blood in a state of decomposition ; and in horned cattle 

 and sheep, from the lodgment of the larvae of the QEstrus bovis. 



General Syynptoins. — " In the majority of instances there will 

 be an irregular discharge from one nostril, indicating that the 

 sinuses of that side of the head only are affected. This dis- 

 charge will also vary very much in its quality, according to the 

 nature of the malady, the duration of the disease, and the struc- 



