THE ORGANS OF DIGESTION 



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 frenum, in the floor of the mouth, is a longitudinal elevation or ridge, 

 produced by the projection of the sublingual gland, which lies immmediately beneath the mucous 

 membrane. And close to the attachment of the frenum to the tip of the tongue may be seen 

 on either side the slit-like orifices of the submaxillary 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 ihefrena; these are not so large as the frenum linguse. 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 the parotid duct. The 

 exact position of the orifice of the duct will be found to be opposite the second upper molar 

 tooth. 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. These, 

 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 con- 

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

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

 fauces are the anterior and posterior pillars, formed by the Palatoglossus and Palatopharyngeus 

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

 side is situated the tonsil. 



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 ptery'gomaxillary 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 mylohyoid ridge of the lower jaw. It connects the Buccinator 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 p. 996). 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 per- 

 forming the operation of staphylorrhaphy. About one-third of an inch (8 mm.) 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 posterior or descend- 

 ing 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 mandible can be felt, and it is especially prominent when the jaw is dislocated. By throw- 

 ing 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 vertebrae may be felt immediately beneath the thin muscular stratum form- 

 ing 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 nasopharynx can be ascertained. 



Applied Anatomy. The duct of a salivary gland may be blocked by a calculus, and the 

 condition is often productive of severe pain. 



A wound of the parotid duct or of the parotid gland may be followed by a salivary fistula. 



The parotid recess is completely lined by fascia, except above. " Between the anterior edge 

 of the styloid process and the posterior border of the External pterygoid muscle there is a gap 

 in the fascia, through which the parotid space communicates with the connective tissue about 

 the pharynx." 



This explains why there is frequently swelling of the parotid region in postpharyngeal abscess. 

 A parotid abscess rarely bursts through the skin ; it may pass into the temporal fossa, may enter 

 the zygomatic fossa, may advance toward the mouth, pharynx, or neck. Because of the situa- 

 tion of^the gland, a parotid abscess may cause inflammation of the temporomandibular joint or 

 periostitis of the bone about the meatus, and may even burst into the external auditory meatus 

 (Treves). 



