THE PHARYXX 949 



the (h'c|) lohe just described, io open l>y a small oi'ilice on the snnnnit of a jiapilla 

 by the side of the fra.'uuiii of the tongue. In this course it is crossed su|»erlicially 

 by the Iin<fual nerve. It lies at iirst between the niylo-hyoid and hyo-glossus; next, 

 between the niylo-hyoid and genio-hyo-glossus; and lastly, under cover of the 

 mucous membrane of the mouth, between the <ienio-hyo-glossus and the sublincrual 

 jrland. The duct is about two inches (5 cm.) in length, and has com])aratively 

 thin coats. It is lined by columnar epithelium. 



The arteries to the gland are derived from the facial and lingual, and they are 

 accompanied l)y corrcsi)onding veins. 



The nerves proceed from the submandil)ular ganglion, from the mylo-hyoid of 

 the mandiliuLir nerve, and from branches of the synii)atheti(-. 



The SUBLINGUAL GLAND — the smallest of the salivary glands — is al)Out one 

 drachm in weight. It lies beneath the f(jre })art of the tongue and mucous mem- 

 brane of the tloor of the mouth, resting deeply upon the mylo-hyoid muscle. Its 

 position is indicatetl by a ridge of mucous meml)rane, the sublingual ridge, which 

 runs outwards and backwards from the fraenum. It is limited externally by the 

 sublingual fossa of the mandil)le, and internally by the genio-hyo-glossus, stylo- 

 glossus, and Wharton's duct; in front it touches its fellow, and behind it approaches 

 the deep lol>e of the submaxillary gland. 



The duct from the main portion of the gland — the duct of Rivinus oi- Bartholin 

 — runs alongside the sulmiaxillary duct, and opens either into it or on llie same 

 pa|)illa. The fore part of the gland consists of a cluster of little lobules, each with 

 its own separate duct — the ducts of "NValther. They open in a line on the floor of 

 the mouth, on the sublingual ridge. 



The arteries are derived from the sul)lingual and suljinental, with their cori'e- 

 sponding veins. 



The nerves are derived from the gustatory (through the submandibular gan- 

 glion) and from the sympathetic. 



THE PHARYNX 



The pharynx is i)laced l>ehind the nose and mouth, and extends from the base 

 of the skull to the lower part of the cricoid cartilage opposite the sixth cervical 

 vertebra. The soft |)alate jjrojects into it from the front, dividing it into a nasal 

 portion above, and a buccal portion l)elow. 



The openings of the two posterior nares which are in front, and the orifices of 

 the two Eustachian tubes, one on each side, open into the naso-])harynx; -whilst 

 into the buccal ])ortion l)clow the velum are the single openings of the mouth in 

 front, and the larynx and a\sophagus below. 



Thus there are seven openings leading into its cavity. 



It measures from above; downwards about four and a half inches (11 "3 cm.). 

 It is flattened from before backwards, so that the cavity in this direction is 

 extremely contracted, its mucous membrane, especially above, being thrown into 

 numerous folds and recesses; whilst below the cavity becomes entirely obliteratt^d, 

 and its anterior and ]>osterior walls, except during the act of swallowing, are in 

 actual contact. It is widest opposite the cornua of the hyoid l)one, and narnjwest 

 below wbei'e it jiasses into the (eso])hagus. 



The pharyngeal walls arecomi)osed of a fibrous coat, the ])haryngeal ajtoneu- 

 rosis, lined l)y a nuicous memliranc, and sumamded externally by muscular layers 

 invested by a delicate areolar sheath which lies i)en(>ath the stronger post-jiharyngeal 

 fascia. 



The pharyngeal aponeurosis is well marked above, l)ut lielow it loses its density 

 and gradually disappears as a definite structure. Above, it is attached to the basi- 

 occipital bone in front of the jtharyngeal tubercle. Its attachment may be traced 



