THE NASAL CAVITIES. 1 



;i single muscle placed <>n tin- widened portion of tin- cartilaginous 

 pieees ; tin- mpermaxiUo-iuuaUs >;//* (ililntnfm- miri* l'it< riills Percivall), 

 rmuiiliil ninx,-Ii- nf tin- nose, whose insertion occupies the whole extent 

 of the external wing; the rapenNOxiZZiMiaMKt JMTMU (ncualis brevis Inlni 

 nni ri<n /.- - IVreivall), fixed, by its two portions, to tho skin of tho false 

 nostril; the miilillf anterior (cfeprflMOT alee nasi Percivall) which is cn- 

 fotinded, superiorly, with tho external fasciculus of the preceding muscle, 

 it being attached to the inferior branch of the cartilaginous appendix of the 

 maxillary turbinated bom; ; and, lastly, the supcrnaso-labialis (levator labii 

 superioris alrqui- imxi - IVrcivall), whose anterior branch is inserted, in 

 part, into the external wing. All these muscles having been described in 

 the Myology (page 220), need not be further alluded to here. 



Iutc<jn UK a I x f the nose. The skin covering the alfe of the nose, ex- 

 ternally, is doubled over their free margin to line their internal face, being 

 prolonged over the entire extent of the false nostril, and is continued, in 

 the nasal fossa), properly called, by the pituitary membrane. This skin is 

 line, thin, charged with colouring pigment, often marked by leprous spots, 

 and adheres closely to the muscles included between its duplicatures, through 

 the medium of a very dense and resisting fibro-cellular tissue. 



Vessels and nerves. The nostrils are supplied with blood by the superior 

 coronary, the .' /' mal nasal, and the palato-labial arteries ; it is returned by the 

 glosso-facial reins, and partly by the venous network of the nasal mucous 

 membrane. The lymphatics, large and abundant, receive those of the 

 pituitary membrane, and join the submaxillary glands by passing over the 

 cheeks. The nerves are very numerous, the sensory being derived from 

 the maxillary branch of the fifth pair, and the motors from the facial 

 nerve. 



FUNCTIONS. The nostrils permit the entrance to tho nasal cavities, 

 of the air which is to pass to the lungs. Their dilatability allows the 

 admission of a greater or less volume, according to the demands of 

 1 1 >piration. It is to be remarked that, in Solipeds, the nostrils constitute 

 the only channel by which the aerial column can be introduced to the 

 trachea, iii consequence of the great development of the soft palate, which is 

 op posed to the entrance of air by tho mouth ; these orifices are also, for the 

 relatively larger than in the other domesticated animals, in 

 which tho passage of air, by the buccal cavity, is easily accomplished. 



2. The Nasal Fossae. (Figs. 223, 224.) 



Channeled in the substance of the head, above and in front of the palate, 

 and separated from one another, in the median plane, by a cartilaginous 

 > jitiini which does not exist in the skeleton, the mu-al fossa) extend from tho 

 nostrils to the cribriform plate of the ethmoid bone, in a direction parallel 

 to tho larger axis of the head. Their length is, therefore, exactly measured 

 by that of the face. See Fig. 223 for tho whole of these cavities. 



The nasal fossa) are formed by two lateral .///>, a r<,f or arch, & floor, and 



In until x. 



\\'nlls. The two walls are very close to each other, and the more- so M 

 they an- examined towards tho ethmoid bone and tho roof of tho cavity. The 

 iratii.g them varies, in proportion as it is measured at the levi-1 <>t 

 tlie turbinated bones or at tho meat uses. 



/ wall. This is formed by the nasal septum, and is perfectly 

 smooth. 



