THE PHARYNX. 721 



beneath the mucous membrane of the floor of the mouth, at the side of the 

 fraenum linguae, in contact with the inner surface of the lower jaw, close to the 

 symphysis. It is narrow, flattened, in shape somewhat like an almond, and 

 weighs about a drachm. It is in relation, above, with the mucous membrane; 

 below, with the Mylo-hyoid muscle; in front, with the depression on the side 

 of the symphysis of the lower jaw, and with its fellow of the opposite side; 

 behind, with the deep part of the submaxillary gland; and internally, with the 

 Genio-hyo-glossus, from which it is separated by the lingual nerve and Whar- 

 ton's duct. Its excretory ducts (ductus Riviniani), from eight to twenty in 

 number, open separately into the mouth, on the elevated crest of mucous mem- 

 brane, caused by the projection of the gland, on either side of the fraBnum 

 linguae. One or more join to form a tube which opens into the Whartonian 

 duct: this is called the duct of Bartholine. 



Vessels and Nerves. The sublingual gland is supplied with blood from tho 

 sublingual and submental arteries. Its nerves are derived from the gustatory. 



Structure. The salivary are conglomerate glands, consisting of numerous 

 lobes, which are made up of smaller lobules, connected together by dense areo- 

 lar tissue, vessels, and ducts. Each lobule consists of numerous closed vesicles, 

 which open into a common duct: the wall of each vesicle is formed of a delicate 

 basement membrane, lined by epithelium, and covered on its outer surface with 

 a dense capillary network. In the submaxillary and sublingual glands, the 

 lobes are larger and more loosely united than in the parotid. 



THE PHARYNX. 



The Pharynx is that part of the alimentary canal which is placed behind the 

 nose, mouth, and larynx. It is a musculo-membranous sac, somewhat conical in 

 form, with the base upwards, and the apex downwards, extending from the 

 under surface of the skull to the carotid cartilage in front, and the fifth cervical 

 vertebra behind. 



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

 transverse than in the antero-posterior diameter. Its greatest breadth is oppo- 

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

 oesophagus. It is limited, above, by the basilar process of the occipital bone; 

 beloiv, it is continuous with the oesophagus; posteriorly, 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 larynx; laterally, it is con- 

 nected to the styloid processes and their muscles, and is in contact with the 

 common and internal carotid arteries, the internal jugular veins, and the eighth, 

 ninth, and sympathetic 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 posterior nares are the two large apertures situated at the upper part of 

 the anterior wall of the pharynx. 



The two Eustachian tubes open one at each side of the upper part of the 

 pharynx, at the back part of the inferior meatus. Below the nasal fossas is the 

 posterior surface of the soft palate and uvula, the large aperture of the mouth, 

 the base of the tongue, the epiglottis, and the cordiform opening of the larynx. 



The oesophageal opening is the lower contracted portion of the pharynx. 



Structure. The pharynx is composed of three coats : a mucous coat, a mus- 

 cular layer, and a fibrous coat. 



The fibrous coat is situated between the mucous and muscular layers, and is 

 called the pharynrjeal aponeurosis. It is thick above, where the muscular fibres 

 are wanting, and is firmly connected to the basilar process of the occipital and 

 46 



