THE LARYNX 465 



the septum nasi in adaptation to the habit of rooting. A plate of cartilage, 

 representing the lamina of the alar cartilage of the horse, curves outward and 

 downward from the upper part of the os rostri and a pointed bar of cartilage 

 curves upward from the lower part of the bone in the outer wing of the nostril. 

 The notch between the nasal bone and the premaxilla is closed in by parietal 

 cartilages which resemble those of the ox. 



The nasal cavity is long and narrow. It is divided behind by a horizontal 

 plate into an upper olfactory part, which leads to the ethmoidal meatuses, 

 and a lower respiratory part, which is a direct continuation of the inferior meatus. 

 The posterior ])art of the septum is membranous. 



The turbinal bones resemljle in general those of the ox. The superior meatus 

 is exceedingly small. The middle meatus is a deep fissure between the two turbinals : 

 it divides posteriorly into two branches; one of these extends upward and Imck- 

 ward between the lateral mass of the ethmoid bone and the superior turbinal; 

 the other widens and joins the inferior meatus. The opening between the maxillary 

 sinus and the raitldle meatus lies in a plane through the last cheek teeth. The 

 mitldle meatus is continuous with the space inclosed by the dorsal part of the in- 

 ferior turbinal and with the cavit}' of the superior turbinal. The dorsal division 

 of the middle meatus presents several openings into the frontal sinus. The in- 

 ferior meatus is relatively roomy; it communicates with the space inclosed by 

 the ventral coil of the inferior turbinal. The opening of the naso-lacrimal duct is 

 found in the posterior part of the inferior meatus. The naso-palatine duct and 

 the vomero-nasal organ (of Jacobson) resemble those of the ox. 



THE LARYNX 



The larj-nx is remarkable for its great length and mobility. The cartilages 

 are more loosely attached to each other than in the other animals. The cricoid 

 cartilage is thick and compressed laterally; its lamina is long and narrow; its 

 arch is directed obliciuely downwartl and backward. The thyroid cartilage is very 

 long; its laminae are united ventrally and form a median ridge. The anterior 

 cornua being absent, there are no joints formed with the hyoid bone. The pos- 

 terior cornua are broad, bent inward, and articulate with the cricoid cartilage. 

 The epiglottis is relatively very large, and is more closely attached to the hyoid 

 bone than to the rest of the larynx. The middle part of its base is turned forward, 

 and rests on the thyro-hyoid membrane; it is closely connected with the body of 

 the hyoid bone by the hj'o-epiglottic ligament and the strong hyo-epiglottic muscle.^ 

 The apex of the arytenoid cartilage is very large, and is divided into two parts at 

 its extremity; the inner part is fused with that of the opposite cartilage. There is 

 a small interarytenoid cartilage in the transverse ligament. The rima glottidis 

 is very narrow. The vocal cords are directed obliquely downward and backward; 

 and each is pierced by a long, slit-like opening, which leads into the large laryngeal 

 saccule. The thyro-arytenoid or vocal ligament is similarly divided into a larger 

 anterior and a smaller posterior part. There is a middle ventricle near the base of 

 the epiglottis. The thyi'o-arytenoid muscle is very strong and is undivided. The 

 arytenoideus is very small. The crico-thyroid consists of two strata; the super- 

 ficial layer corresponds to the muscle of the other animals; the deep part consists 

 of transverse fibers. 



^ The arrangement here is one of the most striking features of the pig's larynx. The short, 

 thick middle hyo-epiglottic ligament and the anterior part of the thyro-hyoid membrane are 

 inelastic, while the posterior part of the membrane is thin and elastic and allows the epiglottis 

 to be separated by a considerable interval from the thyroid cartilage. Morever, the borders of 

 the epiglottis are connected with the thyroid cornua of the hyoid bone by lateral hyo-epiglottic 

 ligaments. 

 30 



