950 THE ORGANS OF DIGESTION. 



more highly civilized races render the orifice of the mouth much smaller, and thus a small 

 mouth is an indication of intelligence, and is regarded as an evidence of the higher civilization 

 of the individual. 



Upon looking into the mouth, the first thing we may note is the tongue, the upper surface 

 of which will be seen occupying the floor of the cavity. This surface is convex, and is marked 

 along the middle line by a raphe which divides it into two symmetrical portions. The anterior 

 two-thirds is rough and studded with papillae ; the posterior third smooth and tuberculated, 

 covered by numerous glands which project from the surface. Upon raising the tongue the 

 mucous membrane which invests the upper surface may be traced covering the sides of the 

 under surface, and then reflected over the floor of the mouth on to the inner surface of the 

 Vower jaw, a part of which it covers. As it passes over the borders of the tongue it changes its 

 character, becoming thin and smooth and losing the papillse which are to be seen on the upper 

 surface. In the middle line the mucous membrane on the under surface of the tip of the 

 tongue forms a distinct fold, the frcenum linguae, by which this organ is connected to the sym- 

 physis of the jaw. Occasionally it is found that this fraenum is rather shorter than natural, 

 and, acting as a bridle, prevents the complete protrusion of the tongue. When this condition 

 exists and an attempt is made to protrude the organ, the tip will be seen to remain buried in 

 the floor of the mouth, and the dorsum of the tongue is rendered very convex, and more or 

 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 ranine 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. And 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. 

 En 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 frcena ; 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 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 Palato-glossus and Palato-pharyngeus 

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

 side is situated the tonsil. By their external surface these glands are in close relationship with 

 the internal carotid artery, being separated from this vessel only by the thin plane of muscular 

 fibres forming the wall of the pharynx. It is stated that this vessel may be wounded in remov- 

 ing the tonsil. The extirpation of this glandular body is not unattended with danger of 

 haemorrhage from other sources. Dr. Weir has stated that he believes that when haemorrhage 

 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 810). 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 



