T1IR LARYS\. 449 



TllO ft'lHl* r>J tin (jri'ft/ i Uimoiilnl << II Ciimpi.rts itx-lf :n, in tlf I|.>r-e. 



'1'ln re i- niil\ niii- pair of iti.i'ill<tri/ >/;/)/-/>, \\hich urn very large, and partitioned into 

 ai|i.irtinriitH by a plate of bone, tliat hears at it- MI[M ri.>r border tin- supcrnmxillo- 

 denlal canal. like tli.' superior iiinxillaiy sinus of S.-Iipeds. Tin- external or maxillary 

 compartment i> prolonged into tin- lachrymal protuberance ; ilu- internal occupi- 

 thickness nf tin- palatine aroh. A wide orifice at the base of the maxillary turbinated 

 iMine a Herds a communication between this sinus and the nasal fossa. 



In the >'/<< y< ;.nd (iout, then- exists a similar arrangement of tho sinuses of the 

 luad ; hut tin .-e cavities are much less spacious than in the Ox; the frontal sinus, in 

 particular. does not extend beyond the sni>erior border of the frontal Inine. 



In the I'iij, these latter sinuses ure prolonged into tl:e piri.-tal bones; though they 

 are far from offering the same extent a- in the .-mailer Kniuinants. It is the same with 

 the i-thers : they present an arrangement analogous to those of the Sfheep and Goat. 



In the Dog and Cut, there ;,re only, on adi side a maxillary and a frontal sinus. 

 The tir.-t scarcely merits notice ; and the second, a little more developed, opens into the 

 nasal cavity by means of a small aperture situated near the middle septum of the two 

 frontal .-inuscs. 



( I .eyli .-tales that the Carnivore have no maxillary sinus ; consequently, the aphenoidal 

 sinus communicates below with the nasal fossa).) 



COMPARISON OF THE NASAL CAVITIES IN MAN WITH THOSE OF ANIMALS. 



The external orifices of the nasal cavities of Man nre called nostrils ; these are flattened 

 transversely, and prolonged in front of the lobule of the nose; their external face or ala 

 is concave and movable. They are lined internally by a membrane that holds a middle 

 pl;,.-. IH -tween the skin and mucous membranes ; it has a number of little hairs, called 



The car// /a* or natal fossx offer nothing particular; as in animals, they show a superior, 

 mil Idle, and inferior meatus. On their floor, in front, is seen the superior orifice of the 

 incisive foramen, which corresponds to the commencement of Jucobson's canal. The 

 jiituitiiry iiiemltrane has a sqnamous epithelium in its olfactory, as on its Schneiderian 

 portion. At the Iwttom of the nasal cavities and the upper part of the pharynx, is a 

 kind of divertii'iilnni named the posterior nareg; it has been already alluded to when 

 speaking of the pharynx. 



The xiiiwK* ure : 1, The sphenoidal sinus and the posterior ethmoidal cells, thnt open 

 the roof of the nasal fossa?; 2, The middle ethmoidal cells, opening inti> tin- 

 meatns; 3, The anterior ethmoidal cells, and frontal and maxillary sinuses, 

 with the middle meatus. All these sinuses have a proper communicating 

 with the nasal cavities. 



THE AIR TUBK SUCCEEDING THE NASAL CAVITIES. 



Tins single tube comprises : the larynx, \\-Jiich commences the tnit'ltcn ; 

 the latter forms tho body or middle- portion, the In-onch'nr terminating it. 



1. Larynx. (Figs. 227, 228, 229.) 



/V./..H.I//.... -1. Make a longitudinal M-ction of the head, in order to study the 



jvneial d>po-itin "| the larynx (!'!_'. --I . -. l-"late the cartilages, to examine 



d c in!i>niiatiiui. :t. Kelimve tin: inilx'le.- from a third laiynx, to .-ho.v the 



ilu -de of articulation of the vaiii'ii^ eartilaire* l-'i_-~. J'_'7. '!!* . I. 1'ri pan tli. mnwles in 



conf.iriiiity with the indication* furnished by a glance at ti^-iir. _'_".'. ^. Uemn\e a hn \ ii\ 



aa carefully an i>ossible, K> as not to injure the walls of the pharynx, in order to study 



itcrior of the organ, and i >]>ceially its pharyngeal 



Form Situation. The larynx forms a very short canal, which gives 

 passage to the air during respiration, and is at tho same time the organ 

 of tho voice. 



i cartilaginous box, depressed on ench side, mul <>]> n from our end to 

 tin- >tlirr : tin; anterior orifice being situated at the bottom of the pharyngcal 

 eavity. and the posterior contimioUK with the trachea. 



Tliis uj)[>aratuH, situated in tho intermaxillary space, is suspended 



'n the two eornna of the os hyoides, and fixed to tho extremities of 



by one of itu constituent pieces. It serves to support the 



2 o 



