PHARYNX. 



949 



part of the pharynx its free surface presents 

 numerous slight elevations occasioned by the 

 glands which are situated beneath it; these in- 

 deed are scattered over the whole pharynx, but 

 are especially abundant at its upper part, where 

 they form a compact lamina between its mus- 

 culo-membranous tunic and the mucous mem- 

 brane, opening upon the surface of the latter 

 by slender ducts. 



5. Vessels and nerves. The bloodvessels 

 distributed to the pharynx are derived from 

 several sources, but chiefly from an especial 

 trunk, viz. the ascending or inferior pharyngeal 

 artery ; this vessel arises from the posterior part 

 of the external carotid, often its first branch, 

 near the bifurcation of the common carotid ; it 

 ascends to the base of the skull, lying close by 

 the side of the pharynx and upon the rectus 

 capitis anticus major muscle, sending off nu- 

 merous small branches, which, intermingling 

 with the pharyngeal plexus of nerves, are dis- 

 tributed to the constrictors and stylo-pharyn- 

 geus, to the velum, arches of the palate and 

 tonsil, ending in minute ramifications on the 

 mucous membrane ; the next most regular sup- 

 ply is from the inferior palatine and tonsillitic 

 branches of the facial artery ; the internal max- 

 illary, lingual and superior thyroid vessels con- 

 tribute an irregular supply of small and unim- 

 portant twigs. The veins form a considerable 

 plexus, the pharyngeal venous plexus, which is 

 produced chiefly by the frequent anastomoses 

 of the pharyngeal vein with the small branches 

 that accompany the inferior palatine and tonsil- 

 litic arteries, and with some of the commencing 

 twigs of the internal maxillary vein ; the pha- 

 ryngeal vein, which receives the blood from 

 this plexus, opens, either singly or in conjunc- 

 tion with the lingual, into the internal jugular 

 vein ; of the lymphatics, but little is known ; 

 they probably enter the chain of glands which 

 lie along the outer side of the carotid sheath. 

 An intricate plexus of nerves, the pharyngeal 

 plexus, is situated upon the sides of the pha- 

 rynx, the branches being particularly numerous 

 upon the middle constrictor muscle near its 

 origin ; it is of some length, and subject to 

 variety in the number of its filaments in diffe- 

 rent subjects ; it interlaces with the ramifica- 

 tions of the arterial twigs from the ascending 

 pharyngeal, and derives its branches from the 

 three portions of the eighth pair of nerves and 

 from the superior cervical ganglion of the sym- 

 pathetic ; the glosso-pharyngeal nerve sends 

 downwards two or more branches to the plexus; 

 one of these I have seen to join the superior 

 laryngeal nerve ; they are given off just before 

 the nerve winds round the lower border of the 

 stylo-pharyngeus muscle ; subsequently one or 

 two branches penetrate this muscle to be distri- 

 buted to the pharyngeal mucous membrane ; 

 the pneumo-gastric detaches one or two pharyn- 

 geal branches; the larger one appears in a great 

 measure formed by a branch from the spinal 

 accessory nerve ; these join with the filaments 

 from the glosso-pharyngeal ; the superior laryn- 

 geal nerve by its external branch also contri- 

 butes a few filaments ; lastly, from the superior 

 cervical ganglion of the sympathetic, twigs are 



derived, which, communicating with those 

 already mentioned, complete this intricate 

 plexus ; the branches from it are distributed to 

 the pharyngeal walls, to the soft palate, and 

 stylo-pharyngeus muscles. The digastric branch 

 of the facial nerve and the lingual or its de- 

 scending branch are described as sometimes 

 communicating with this plexus : for the more 

 minute anatomy of these nerves see PAR 

 VAGUM, GLOSSO-PHARYNGEAL NERVK, AND 

 SPINAL ACCESSORY. 



Mouth, (Gr. o-Topa.; Lat. os; Fr. bouche.) 

 The mouth is an oval cavity, symmetrical, and 

 situated at the lower part of the face, below 

 the nasal fossae, between the jaws, and in front 

 of the pharynx, with which it communicates by 

 a posterior opening, called the isthmus fau- 

 cium, and has also a dilatable aperture ante- 

 riorly guarded by the lips : it is liable to con- 

 siderable alterations of form and size, from 

 complete closure to a state of extreme exten- 

 sion, when it represents a quadrangular py- 

 ramid with the base in front: the greatest 

 change occurs in its vertical diameter from the 

 movements of the lower jaw; in it are per- 

 formed the various functions of mastication, 

 tasting, partly that of deglutition, and it is 

 subservient also to the production of articulate 

 sounds. The mouth or buccal cavity is bounded 

 both laterally and anteriorly by the alveolar 

 borders of the upper and lower maxillary bones 

 and teeth, the lips completing the boundary 

 in front and the cheeks laterally: above it is 

 roofed in by the arched palate and more pos- 

 teriorly by the velum palati ; inferiorly the 

 tongue forms its floor. In the examination of 

 these boundaries the reader is referred to the 

 articles FACE and TEETH for the description 

 of the maxillary bones and teeth. 



The lips (labia) are two moveable curtains 

 placed in front of the mouth, presenting be- 

 tween them when applied to each other a 

 transverse slit convertible by their separation 

 into a more or less considerable opening, which 

 constitutes the anterior aperture of the buccal 

 cavity : the lips are united at the lateral limits 

 of this fissure to form the commissures or 

 angles; the anterior surface of the upper lip, 

 which usually projects a little beyond the lower, 

 is covered with hair in the adult male, and 

 exhibits in the median line a vertical groove 

 continued to its free border from the septum 

 of the nose : two ridges bound this furrow on 

 either side, and from thence the upper lip 

 passes off laterally to the cheek, insensibly in 

 the young and plump face, but otherwise a 

 line of demarcation is produced by an oblique 

 fold of the skin which descends from the side 

 of the nose to near the commissure of the lips 

 ,on either side of the face: the anterior surface 

 of the lower lip descends more or less abruptly 

 backwards to the chin, divided from it by a 

 transverse groove : it is covered with hair usu- 

 ally at the centre only, and slightly bulging 

 near its free border shelves oft' gradually to the 

 sides of the face : the free borders are the 

 thickest parts of the lips, their large develope- 

 ment forming a characteristic feature in the 

 Negro; in their outline they differ, presenting 



