THE FACE. 1383 



On account of the very slender anastomosis between the vessels of the two halves 

 of the tongue, scarcely any bleeding occurs when the organ is split in the median 

 plane. 



According to Poirier, the collecting trunks which arise from the lymph net- 

 works in the mucous membrane and muscular substance of the tongue may be 

 divided into four groups : (1) Apical trunks which open partly into the submental 

 glands and partly into a gland of the medial deep cervical group lying immediately 

 above the anterior belly of the omo-hyoid muscle. (2) Marginal trunks which pass, 

 some lateral to the sublingual gland and through the mylo-hyoid muscle, to join the 

 most anterior of the submaxillary lymph glands ; others pass medial to the sub- 

 lingual gland, in front of and behind the hyoglossus muscle, to join the glands of the 

 medial deep cervical group. The more anterior their lingual origin the lower in the 

 chain is the gland to which they pass. (3) The basal trunks, from the posterior 

 third of the tongue, pass from before backwards towards the inferior extremity of 

 the tonsils, where they pierce the superior and middle constrictors of the pharynx, 

 and, after surrounding the lingtfal artery, open into a gland placed on the internal 

 jugular vein immediately below the posterior belly of the digastric. (4) The central 

 trunks, which descend in the middle line between the genio-glossi, pass beneath the 

 hyoglossus and mylo-hyoid muscles into the submaxillary space, and thence in 

 front of the hyoid bone (having embraced the tendon of the digastric) to join the 

 glands of the medial deep cervical group. 



Between the tongue and the lingual surface of the gums is the alveolo-glossal 

 sulcus, crossed in the median plane by the frenulum linguae, which passes upwards to 

 the inferior surface of the tongue (Fig. 1084). Immediately on either side of the 

 lower part of the frenulum is the orifice of the submaxillary duct. A little external 

 to the frenulum the profunda veins are seen lying immediately under the thin mucous 

 membrane ; to the lateral side of the veins are the profunda arteries and the lingual 

 nerves, both of which lie deeper than the veins, and are therefore not visible. 



The mucous membrane at the anterior part of the floor of each alveolo-glossal 

 sulcus is thrown into a slight elevation, which overlies, and is caused by, the 

 corresponding sublingual salivary gland. The duct of the submaxillary gland and 

 the lingual nerve lie beneath and to the medial side of the sublingual gland. 



In dividing a shortened frenulum for " tongue-tie " the deep lingual vessels and the 

 orifices of the submaxillary ducts. must be avoided. Behind the frenulum linguae are the 

 anterior borders of the genio-glossi, which descend to the superior genial tubercles. In 

 operations necessitating the removal of the region of the symphysis of the mandible, or the 

 separation of the origins of the genio-glossi, the tongue must be kept forward, otherwise 

 the patient will be suffocated by the organ falling backwards over the entrance to the 

 larynx. In removing a small salivary calculus from the floor of the mouth the calculus 

 should be fixed with the finger against the lingual surface of the mandible before cutting 

 down upon it. 



When the teeth are clenched the vestibule of the mouth communicates behind 

 the last molars with the oral cavity proper through an opening which barely admits 

 1 a medium-sized catheter. Hence, when the jaws cannot be separated it is generally 

 necessary to feed the patient through a tube passed along the floor of the nose. 



When the mouth is opened widely and a deep inspiration is taken, the soft 

 palate is elevated, and the glosso- palatine and pharyngo- palatine arches are 

 rendered prominent. The glosso - palatine arches spring from the anterior 

 surface of the soft palate, close to the base of the uvula, and arch down- 

 wards and laterally, in front of the palatine tonsils, to end at the posterior end 

 of the side of the tongue. The pharyngo-palatine arches are really the continua- 

 tion of the lower free border of the soft palate downwards behind the palatine 

 tonsils to become attached to, and lost upon, the side wall of the pharynx. 

 Together with the lower edge of the soft palate and the base of the tongue they 

 1 bound a hemispherical opening (pharyngo-nasal isthmus), through which the mucous 

 1 membrane covering the posterior wall of the nasal portion of the pharynx is visible. 

 The palatine tonsils (Fig. 1085) lie one on each side of the isthmus, between the 

 palatine arches ; they are situated opposite the angle of the mandible, but they cannot 



88 c 



