270 THE DIGESTIVE SYSTEM 



From these arteries, also, small arterial branches enter the deeper 

 portion of the coriuni and form a capillary plexus which supplies 

 the connective tissue and whose terminal ramifications extend to 

 the very apex of the connective tissue papillae. The blood is re- 

 turned by veins which pursue a similar course. 



The Lymphatics form a superficial set of small vessels and tissue 

 spaces beneath the epithelial layer, which are especially abundant 

 in the region of the lingual tonsil at the base of the tongue. The 

 lymphatic vessels of this superficial plexus frequently encircle the 

 lymphoid nodules. A deeper plexus of lymphatics in the loose 

 connective tissue of the submucosa receives the lymph from the 

 superficial plexus and conveys it by efferent lymphatic vessels to 

 the deep cervical lymphatic glands. 



The Nerves of the tongue are derived from the lingual, glosso- 

 pharyngeal, and chorda tympani. The larger trunks accompany 

 the arteries, lying near the median line on the under surface of 

 the tongue, and are embedded in the connective and adipose tissue 

 between the muscle bundles of this portion of the organ, small 

 ganglia occurring along their course. From these nerve trunks, 

 fibres are distributed to the muscular tissue and to the corium. 

 The former terminate in muscle plates in the striated muscle fibres, 

 in the walls of the larger blood vessels to which both sensory and 

 motor fibres are distributed, and in sensory endings in the muscle 

 spindles and connective tissue. The smaller nerves of the corium 

 supply the blood vessels of this tissue and send minute fibrils to 

 the epithelium, which terminate in delicate knobbed extremities 

 between the epithelial cells. 



At the base of the tongue small nerve bundles are distributed 

 to the circumvallate papillae, and form a subepithelial plexus 

 from which fibrils are distributed : 1, to the interior of the taste 

 buds where they end in relation with the gustatory cells, intragem- 

 mal fibres ; 2, to the surface of the taste buds, perigemmal fibres ; 

 and 3, to the intervening portions of the epithelial layer, where 

 they end between the epithelial cells as in other parts of the 

 tongue, intergemmal fibres (Fig. 120, page 125). 



