THE PHAEYNX. 



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^ ment (nasal portion), from the posterior margin of the septum of the nose at its inferior part 

 horizontally backwards, measures 15 to 18 mm., and that of the middle segment, from the glosso- 

 palatine arches to the posterior wall, about 10 mm. Below that level, the anterior and pos- 

 terior walls gradually approach one another, until, below the laryngeal orifice, they are in 

 contact with one another. 



The transverse width of the pharynx also varies considerably. Immediately below the base 

 of the skull the cavity is wide, as there is on each side a deep recess, and it measures 45 mm., or 

 nearly 2 inches. 



Opposite the middle of the soft palate the cavity narrows, and measures transversely 25 mm., 

 or 1 inch. 



It again widens out below this level, and expands to a width of 35 mm., opposite the inferior 

 margin of the laryngeal opening, where on each side there is a wide recess, called the piriform recess. 



Pharyngeal tonsil 

 Dura mater / Tuba auditiva, labium posterius 



Sinus transversus 

 Mastoid process 



f- V. jugularis interna 



A. carotis interna 



. sterno-cleido-mastoideus 

 M. levator veli palatini 



M.- digastricus 



Ganglioi 



N. accessorius 

 N. laryngeus superior 

 M. constrictor pharyngis 

 medius 



M. stylopharyngeus 



M. pter. interims 

 A. car. externa 



M. pharyngopalatinus 



M. stylohyohleus 



M. constrictor pharyngis 

 medius 



A. maxillaris externa 

 A. pharyngea ascendens 

 A. lingualis 



I. constrictor pharyngi 

 inferio 



A. carotis externa 



Os hyoideum cornu (major) 



V. jugularis interna 



N. sterno-cle'ido-mastoideus 



FIG. 901. INTKRIOR OF PHARYNX AND STRUCTURES IN RELATION TO ITS SIDE WALLS, 



VIEWED FROM BEHIND. 



Cavum Pharyngis. The cavity of the pharynx is partially intersected by the 

 soft palate, which is attached anteriorly to the hard palate, and laterally to the 

 side walls of the pharynx. This sheet, sloping obliquely backwards and down- 

 wards, cuts into the cavity of the pharynx (Fig. 901), and, falling short of the 

 posterior wall, incompletely divides it into two, namely, an upper part, pars nasalis 



C. naso-pharynx), and a lower part or pharynx proper. This lower portion is 

 further subdivided into the pars oralis (O.T. oral pharynx), lying behind the mouth 

 and tongue, and the pars laryngea (O.T. laryngeal pharynx), behind the larynx. 



The aperture left between the soft palate and the posterior wall of the 

 tiarynx, through which the nasal part of the pharynx communicates with the 

 inferior divisions of the cavity, is called the isthmus pharyngonasalis. 



The pharynx presents seven openings by which it communicates with 



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