THE PHARYNX. 889 



less extruded from the mouth ; at the same time a deep furrow will be noticed to appear in the 

 middle line of the anterior part of the dorsum. Sometimes, a little external to the fraenum, 

 the rani nc vein may be seen immediately beneath the mucous membrane. The corresponding 

 artery, being more deeply placed, does not come into view, nor can its pulsation be felt with the 

 finger. On either side of the fraenum, in the floor of the mouth, is a longitudinal elevation or 

 ridge, produced by the projection of the sublingual gland, which lies immediately beneath the 

 mucous membrane. Arid close to the attachment of the fraenum to the tip of the tongue may 

 be seen on either side the slit-like orifices of Wharton's ducts, into which a fine probe may be 

 passed without much difficulty. By everting the lips the smooth mucous membrane lining them 

 may be examined, and may be traced from them on to the outer surface of the alveolar arch. 

 In the middle line, both of the upper and lower lip. a small fold of mucous membrane passes 

 from the lip to the bone, constituting the fnvnn ; these are not so large as the fraenum linguae. 

 By pulling outward the angle of the mouth, the mucous membrane lining the cheeks can be 

 seen, and on it may be perceived a little papilla which marks the position of the orifice of Sten- 

 son's duct the duct of the parotid gland. The exact position of the orifice of the duct will be 

 found to be opposite the second molar tooth of the upper jaw. The introduction of a probe 

 into this duct is attended with considerable difficulty. The teeth are the next objects which 

 claim our attention upon looking into the mouth. There are, as stated above, ten in either jaw 

 in the temporary set, and sixteen in the permanent set. The gums, in which they are implanted, 

 are dense, firm, and vascular. 



At the back of the mouth is seen the isthmus of the fauces, or, as it is popularly called, 

 "the throat:" this is the space between the pillars of the fauces on either side, and is the 

 means by which the mouth communicates with the pharynx. Above, it is bounded by the soft 

 palate, the anterior surface of which is concave and covered with mucous membrane, which is 

 continuous with that lining the roof of the mouth. Projecting downward from the middle of 

 its lower border is a conical-shaped projection, the tn-uki. On either side of the isthmus of the 

 fauces are the anterior and posterior pillars, formed by the Palato-glossus and Palato-pharyngeus 

 muscles respectively, covered over by mucous membrane. Between the two pillars on either 

 side is situated the tonsil. The extirpation of this body is not unattended with danger of 

 hemorrhage. Dr. Weir has stated that he believes that when hemorrhage occurs after their 

 removal it arises from one of the palatine arteries having been wounded. These vessels are 

 large : they lie in the muscular tissue of the palate, and when wounded are constantly exposed 

 to disturbance from the contraction of the palatine muscles. The vessels of the tonsil, Dr. Weir 

 states, are small and lie in the soft tissue, and readily contract when wounded. 



When the mouth is wide open a prominent tense fold of mucous membrane may be seen 

 and felt, extending upward and backward from the position of the fang of the last molar tooth 

 to the posterior part of the hard palate. This is caused by the Pterygo-maxillary ligament, 

 which is attached by one extremity to the apex of the internal pterygoid plate, and by the other 

 to the posterior extremity of the mylo-hyoid ridge of the lower jaw. It connects the Buccina- 

 tor with the Superior constrictor of the pharynx. The fang of the last molar tooth indicates 

 the position of the lingual (gustatory) nerve, where it is easily accessible, and can with readiness 

 be divided in cases of cancer of the tongue (see page 735). On the inner side of the last molar 

 tooth we can feel the hamular process of the internal pterygoid plate of the sphenoid bone, 

 around which the tendon of the Tensor palati plays. The exact position of this process is of 

 importance in performing the operation of staphylorraphy. About one-third of an inch in 

 front of the hamular process, and the same distance directly inward from the last molar tooth, 

 is the situation of the opening of the posterior palatine canal, through which emerges the pos- 

 terior or descending palatine branch of the internal maxillary artery and one of the descending 

 palatine nerves from Meckel's ganglion. The exact position of the opening on the subject may 

 be ascertained by driving a needle through the tissues of the palate in this situation, when it 

 will be at once felt to enter the canal. The artery emerging from the opening runs forward in a 

 groove in the bone just internal to the alveolar border of the hard palate, and may be wounded 

 in the operation for the cure of cleft palate. Under these circumstances the palatine canal may 

 require plugging. By introducing the finger into the mouth the anterior border of the coronoid 

 process of the jaw can be felt, and is especially prominent when the jaw is dislocated. By 

 throwing the head well back a considerable portion of the posterior wall of the pharynx may be 

 seen through the isthmus faucium, and on introducing the finger the anterior surface of the 

 bodies of the upper cervical vertebras may be felt immediately beneath the thin muscular stra- 

 tum forming the wall of the pharynx. The finger can be hooked around the posterior border 

 of the soft palate, and by turning it forward the posterior nares, separated by the septum, can 

 be felt, or the presence of any adenoid or other growths in the naso-pharynx ascertained. 



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 tube, somewhat conical in 

 form, with the base upward and the apex downward, extending from the under 

 surface of the skull to the level of the cricoid cartilage in front and that of the in- 

 tervertebral disk between the fifth and sixth cervical vertebrae behind. 



