56 TOPOGRAPHIC AND APPLIED ANATOMY. 



PLATE 4. 

 A median sagittal section of the head. Frozen section. 



[Congenital dermoid cysts are frequently found in the floor of the mouth at its junction with 

 the base of the tongue. Retention cysts of the mucous glands, of Wharton's duct, or the ducts 

 of the sublingual glands are called ranula. Congenital cysts or fistulas due to incomplete closure 

 of the thyroglossal duct which extends from the foramen caecum of the tongue to the isthmus of 

 the thyroid are always mesial; when developed from the upper part of the duct, they present in 

 the mouth ; those arising from the lower end present in the neck below the hyoid bone. ED.] 



The tongue, the largest organ in the mouth, lies in contact with the palate when the mouth 

 is closed. Its base reaches to the epiglottis. A median section (Plate 4) shows that a swelling 

 of the tongue may force the epiglottis down upon the entrance of the larynx in such a manner that 

 tracheotomy must be performed. It will also be understood that a paralysis of the muscles from 

 profound narcosis will allow the tongue and epiglottis to fall back so that respiration is interfered 

 with. 



The lingual artery supplies the tongue with blood. This vessel arises in the neck from the 

 external carotid (see page 64), passes above the greater cornu of the hyoid bone beneath the hyo- 

 glossus muscle, and, as the ranine artery, pursues a tortuous course in the tongue between the 

 inferior lingulias and geniohyoglossus muscles. Although it gives off the dorsalis lingua, running 

 upward to the root of the tongue to supply the circumvallate papillas, the chief branch is the sub- 

 lingual artery, which runs anteriorly beneath the sublingual gland to reach the gums of the incisor 

 teeth. Above and to either side of the fraenum, the artery is relatively superficial, and may be 

 caught by a deep suture for the purpose of checking hemorrhage. There are no marked anasto- 

 moses between the arteries of the two sides. In the posterior portion of the tongue the artery is so 

 imbedded in the soft lingual musculature that it may be impossible to control serious hemorrhage 

 from operative procedures by ligation in the wound, and it becomes necessary to ligate the vessel 

 in the neck. 



The lingual branch of the glossopharyngeal nerve supplies the circumvallate papillas [that is, 

 the posterior part of the tongue, with both gustatory and common sensory fibers. ED.]; it is not 

 very large and possesses no surgical importance. The sensory nerve of the tongue, the lingual 

 branch of the inferior maxillary, which also receives gustatory fibers for the fungiform papillas 

 from the chorda tympani, may be easily exposed beneath the mucous membrane at the side of the 

 tongue in the neighborhood of the second molar tooth (see Fig. 20). This nerve runs over the sub- 

 maxillary duct and is also accessible in the neck in the depths of the submaxillary triangle (see 

 page 65). [According to Cunningham, Wolsey, and others, the nerve runs beneath the duct. 

 ED.] The motor nerve, the hypoglossal (see page 64), is more deeply situated [that is, from the 

 floor of the mouth. ED.] beneath the sublingual gland. The inferior dental branch of the 

 superior maxillary division of the fifth may also be easily exposed in the mouth before it enters 

 the inferior dental canal by means of the same incision as that for the lingual nerve. It may 

 also be attacked by dividing the skin and masseter muscle and trephining the ramus of the jaw. 



The numerous lymphatic vessels of the tongue lead to the submental and submaxillary 

 lymphatic glands, which are consequently involved early in affections of the tongue. 



