PHARYNX 375 



through the various apertures which open into the pharynx, 

 with the mucous membrane of the nasal cavities, the auditory 

 tubes and ty?npanic cavities, the mouth proper, the larynx, and 

 the oesophagus. 



Racemose glands, which lie immediately subjacent to the 

 mucous membrane and secrete mucus, are present in great 

 numbers. There are also numerous lymph follicles, and 

 in certain localities these are aggregated together into large 

 masses (the tonsils and the pharyngeal tonsil). These will 

 be studied with the regions of the pharynx in which they 

 are placed. 



The soft palate projects into the pharynx, posterior to 

 the isthmus faucium, and divides the cavity of the pharynx 

 into an upper and a lower part. The upper part, called 

 the naso - pharynx, communicates with the nasal cavities 

 and the tympanic cavities by four apertures, viz. the two 

 choanae (O.T. posterior nares) and the two auditory tubes 

 (O.T. Eustachian tubes). 



The lower portion of the pharynx may be regarded as 

 consisting of an oral part, which lies posterior to the 

 mouth and tongue, and a laryngeal part, placed posterior 

 to the larynx. Below the soft palate there are three 

 openings into the pharynx, viz. the opening of the mouth or 

 isthmus faucium, the opening of the larynx, and the opening of 

 the oesophagus. 



Pars Nasalis. The naso-pharynx is situated immediately 

 posterior to the nasal cavities and below the body of the 

 sphenoid and the basilar part of the occipital bone. It is the 

 widest part of the pharynx. Its walls, except the soft palate, 

 are not capable of movement, and, consequently, its cavity 

 always remains patent, and presents under all conditions very 

 much the same form. 



In its anterior boundary are the choanae, through which it 

 opens into the nasal cavities. The choance are two oblong 

 orifices which slope from the base of the cranium downwards 

 and anteriorly to the posterior border of the hard palate. 

 Each is an inch long and half an inch wide, and it is separated 

 from its fellow by the posterior part of the septum nasi, which 

 in this region is formed by the vomer. By looking through 

 the choanae a partial view of the lower two meatuses of the 

 nose and of the posterior ends of the middle and inferior 

 conchae may be obtained. 

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