890 THE ORGAM Ol- 1>I<; KSTIOX. 



The pharynx is about four inches and a half in length, and broader in the 

 transverse than in the autero-posterior diameter. Its greatest breadth is opposite 

 the cornua of the hyoid bone; its narrowest point, at its termination in the 

 oesophagus. It is limited, above, by the body of the sphenoid and basilar process 

 of the occipital bone ; beloiv, it is continuous with the oesophagus ; posteriori//, it 

 is connected by loose areolar tissue with the cervical portion of the vertebral 

 column and the Longi colli and Recti capitis antici muscles ; anteriorly, it is 

 incomplete, and is attached in succession to the internal pterygoid plate, the 

 pterygo-maxillary ligament, the lower jaw, the tongue, hyoid bone, and thyroid and 

 cricoid cartilages; laterally, it is connected to the styloid processes and their mus- 

 cles, and is in contact with the common and internal carotid arteries, the internal 

 jugular veins, and the glosso-pharyngeal, pneumogastric, hypoglossal, and sym- 

 pathetic nerves, and above with a small part of the Internal pterygoid muscles. 



It has seven openings communicating with it the two posterior nares, the 

 two Eustachian tubes, the mouth, larynx, and oesophagus. 



The pharynx may be subdivided from above downward into three parts, nasal, 

 oral, and "laryngeal. The nasal part of the pharynx (pars nasalis) or naso-pharynx 

 lies behind the nose and above the level of the soft palate : it differs from the two 

 lower parts of the tube in that its cavity always remains patent. In front it com- 

 municates through the choarise with the nasal fossa?. On its lateral wall is the 

 pliaryngeal orifice of the Eustachian tube, which presents the appearance of a 

 tical cleft bounded behind by a firm prominence, the ei^Jt^n, caused by the innert 

 extremity of the cartilage of the tube impinging on the deep surface of the mucous 

 membrane. A vertical fold of mucous membrane, the plica salpingo-pharyrigea, 

 stretches from the lower part of the cushion to the pharynx ; it contains the ISal- 

 pingo-pharyngeus muscle. A second and smaller mucous fold may be seen stretch- 

 ing from the upper part of the cushion to the palate, the plica salpingo-palatina. 

 Behind the orifice of the Eustachian tube is a deep recess, the/osscr of J-fosentn tiller, 

 which represents the remains of the upper part of the second branchial cleft. 



The oral part of the pharynx (pars oralis] reaches from the soft palate to the 

 level of the hyoid bone. It opens anteriorly, through the isthmus faucium, into 

 the mouth, while in its lateral wall, between jhe two pillars of the jauces, is 

 the tonsil. 



The laryngeal part of the pharynx (pars larynged) reaches from the hyoid bone 

 to the lower border of the cricoid cartilage, where it is continuous with the oesoph- 

 agus. In front it presents the triangular aperture of the larynx, the base of which 

 is directed forward and is formed by the epiglottis, while its lateral boundaries are 

 constituted by the aryteno-epiglottidean folds. On either side of the laryngeal 

 orifice is a recess, termed the sinus pyriformis : it is bounded internally by the 

 aryteno-epiglottidean fold, externally by the thyroid cartilage and thyro-hyoid 

 membrane. 



Structure. The pharynx is composed of three coats mucous, fibrous, and 

 muscular. 



The pharyngeal apaneurosis, or fibrous coat, is situated between the mucous 

 and muscular layers. It is thick above, where the muscular fibres are wanting, and 

 is firmly connected to the basilar process of the occipital and petrous portion of the 

 temporal bones. As it descends it diminishes in thickness, and is gradually lost. 

 It is strengthened posteriorly by a strong fibrous band which is attached above to 

 the pliaryngeal spine on the under surface of the basilar portion of the occipital 

 bone, and passes downward, forming a median raphe, which gives attachment to 

 the Constrictor muscles of the pharynx. 



The mucous coat is continuous with that lining the Eustachian tubes, the nares, 

 the mouth and the larynx. In the naso-pharynx it is covered by columnar ciliated 

 epithelium ; in the buccal and laryngeal portions the epithelium is of the squamous 

 variety. Beneath the mucous membrane are found racemose mucous glands ; they 

 are especially numerous at the upper part of the pharynx around the orifices of 

 the Eustachian tubes. Throughout the pharynx are also numerous crypts or 



