982 THE DIGESTIVE SYSTEM. 
lower part or pharynx proper, which is further subdivided—perhaps unnecessarily— 
into the oral pharynx (pars oralis) lying behind the mouth and tongue, and the 
laryngeal pharynx (pars laryngea) behind the larynx. 
The aperture left between the soft palate and the posterior wall of the 
pharynx, through which the naso-pharynx communicates with the lower divisions 
of the cavity, may conveniently be called the pharyngeal isthmus (isthmus 
pbaryngo-nasalis). 
The pharynx presents seven openings through which it communicates with 
neighbouring cavities (Fig. 660). These are the two posterior nares (choanee ) 
on the anterior wall, and the two Eustachian tubes on the sides of the naso- 
———©rbit 
Posterior end of 
middle turbinated~ 
bone 
Pharyngeal tonsil~_ 
Posterior edge of 
~ nasal septum 
——Eustachian cushion 
Antrum of Highmore—! 
_ Orifice of Eustachian 
tube 
Posterior end of 
inferior turbinated— 
bone 
Anterior palatine 
—arch 
Glands in hard 
palate 
_—Tonsil 
Wisdom tooth— 
Buecinator (cut) 
we arch 
Uvula— \\ as aes ‘pr ° Bo Scopes palatine 
\ mee * R ' 
"—~Pharyngeal isthmus 
~~Tongue 
Fic. 662.—THE NASO-PHARYNX FROM THE FRONT. 
A coronal section was made through the upper part of the head; this passed immediately in front of 
the posterior edge of the nasal septum, and extended into the mouth below. Through the posterior 
nares the naso-pharynx is seen. The prominence of the posterior margin of the Hustachian orifice, 
and the lymphoid nodules constituting the pharyngeal tonsil, should be noted. The palatine arches, 
the tonsils, and an unusually wide pharyngeal isthmus, are also seen. 
pharynx ; the isthmus of the fauces leading into the mouth from the oral pharynx ; 
the orifice of the larynx on the anterior wall of the laryngeal portion of the 
cavity; and finally, the opening of the cesophagus at its lower end. 
Naso-pharynx (Figs. 661 and 662).—Although described as a part of the pharynx, 
this portion of the cavity should be regarded as an annex to the respiratory portion 
of the nasal cavities rather than as a subdivision of the pharynx proper, for, both 
anatomically and functionally, it is all but completely marked off from the 
digestive tube. It differs from the rest of the pharynx in that its cavity remains, 
under all conditions, a distinet open chamber incapable of obliteration, owing to 
the fact that all its walls, with the single exception of the floor, are practically 
immovable. 
