

THE PHAKYNX. 1149 



The external carotid lies more superficially, and is here separated by a con- 

 siderable interval from the, pharyngeal wall. 



Lastly, a process of the parotid gland may insert itself on the medial aspect of 

 the internal pterygoid, and come into contact with the pharynx. 



The pharyngeal plexus of nerves lies in contact with the side wall. 



Structure of the Pharyngeal Wall. The wall of the pharynx is strong and 

 mobile ; it is firmly fixed above to the base of the skull, but below that level it is not 

 attached firmly to any surrounding structures, except to the hyoid bone and the skeleton 

 of the larynx, and hence the inferior end can easily be displaced from side to side in 

 the neck. 



The wall is composed of a strong fibrous membrane, called the fascia pharyngo- 

 basilaris (O.T. pharyngeal aponeurosis), lined internally by mucous membrane, and covered 

 incompletely on its outer surface by a series of three overlapping muscles, the constrictor 

 muscles of the pharynx. 



These muscles are themselves covered externally by a thin layer of fibrous tissue 

 or fascia, which passes forwards, at its superior part, on to the surface of the buccinator 

 muscle, and is called the fascia buccopharyngea. 



External to this fascia the wall of the pharynx is in contact with loose cellular tissue 

 by which it is connected to and separated from adjacent structures. 



With the wall of the pharynx are associated several accessory muscles, viz., the 

 muscles of the soft palate and the stylopharyngeus and pharyngo-palatine muscles, which 

 blend with the wall but are also attached to the larynx (see p. 466). 



The fibrous aponeurosis which forms the principal constituent of the pharyngeal 

 wall is firmly attached (round the margins of the openings into the pharynx) to other 

 structures as follows : 



Above, it blends with the periosteum covering the basilar portion of the occipital 

 bone in front of the pharyngeal tubercle, and body of the sphenoid bone, and on each 

 side it extends out to the angular spine of the sphenoid and the apex of the petrous part 

 of the temporal bone. 



On each side, it is attached to the structures which lie on each side of the orifices of 

 the nose, mouth, and larynx. As it descends it gradually becomes thinner, and is 

 eventually lost. 



The fascia pharyngo-basilaris is particularly strong in the superior part, where there is 

 an area on each side which is not covered by the superior constrictor muscle. This area 

 forms the sinus of Morgagni, and here the tuba auditiva and tensor and levator veli 

 palatini muscles pass through the wall. 



Mucous Membrane of the Pharynx. The superficial layer of the mucous 

 membrane of the pharynx consists, in the lower part, of a stratified squamous epithelium, 

 while in the upper or nasal portion it is, in part, composed of ciliated epithelium. In the 

 superior part of the pharynx and in the side wall, there are found large masses of lymph 

 tissue, constituting the pharyngeal tonsil in the roof, and the palatine tonsil on each side. 

 The same tissue is found in considerable amount in the pharyugeal recess and on the 

 pharyngeal portion of the dorsum of the tongue. 



There are also numerous racemose glands, of the mucous type, in the walls of the 

 pars nasalis, and in the soft palate, and in the ary-epiglottic folds. 



Pharyngeal Muscles. For the details of the attachment and relations of these 

 muscles, see pp. 464-467. 



External to the pharyngeal muscles lies the fascia buccopharyngea. 



The fascia pharyngobasilaris, which is thick above and thin belpw, and the fascia 

 bucco-pharyngea, which is thin above and stouter below, are practically blended into one 

 layer above, near the base of the skull, where the muscular coat is absent. Lower 

 down they are separated by the constrictors, and become two distinct sheets. They 

 are strengthened in the median plane posteriorly by a fibrous band descending from the 

 pharyngeal tubercle. 



Vessels and Nerves of the Pharynx. The arteries of the pharynx are derived from 1, 

 the ascending pharyngeal ; 2, the ascending palatine branch of the external maxillary ; 3, the de- 

 scending palatine from the internal maxillary, with a few twigs from the dorsalis linguae, 

 toasillar (of external maxillary), the artery of the pterygoid canal, and the pharyngeal branch 



the internal maxillary. The veins go to the pharyngeal venous plexus, which is found 



ween the constrictors and the bucco- pharyngeal fascia. The plexus communicates with the 

 pterygoid plexus above and with the internal jugular or common facial vein below. 



The lymph vessels of the pharynx pass chiefly to the superior set of deep cervical glands. 



