SUBLINGUAL, OR HYPOGLOSSAL NERVE. 



633 



the passage of the alimentary bolus through the pharynx ; to one of the muscles in the 

 supra-hyoid region, the genio-hyoid ; to most of the muscles which move the tongue ; 

 and to the muscular fibres of the tongue itself. The action of these muscles and of the 

 tongue itself in deglutition has already been fully discussed. 







FIG. 210. Distribution of the sublingual nerve. (Sappey.) 



1, root of the fifth nerve ; 2, ganglion of Gasser ; 3, 4, 5, 6, 7, 9, 10, 12, branches and anastomoses of the fifth nerve ; 

 11, submaxillary ganglion ; 13, anterior belly of the digastric muscle ; 14, section of the mylo-hyoid muscle ; 15, 

 glosso-pharyngeal nerve; 16, ganglion of Andersch; 17, 18, branches of the glosso-pharyngeal nerve; 19, 19, 

 pneumogastric ; 20, 21, ganglia of the pneumogastric ; 22, 22, superior laryngeal branch of the pneumogastric ; 

 23, spinal accessory nerve ; 24, sublingual nerve ; 25, descendens noni ; 2(5, thyro-hyoid branch ; 27, terminal 

 branches ; 28, two branches, one to the genio-hyo-glossuft and the other to the genio-hyoid muscle. 



Properties and Functions of the Sublingual. There is every reason to believe that 

 the sublingual nerve is entirely insensible at its origin from the medulla oblongata. The 

 fact that it arises from a continuation of the motor tract of the spinal cord and has na 

 ganglion upon its main root would lead to the supposition that it is an exclusively motor 

 nerve. In operating upon the roots of the spinal accessory, when the origin of the sub- 

 lingual is necessarily exposed, Longet has irritated the roots in the dog, without any evi- 

 dence of pain on the part of the animal. Such experiments, taken in connection with 

 the anatomical characters of the nerve, render it almost certain that its root is devoid 

 of sensibility at its origin. All modern experimenters have confirmed the observations 

 of Mayo and of Magendie, with regard to the sensibility of the sublingual after it has 

 passed out of the cranial cavity. The anastomoses of this nerve with the upper two 

 cervical nerves, with the pneumogastric, and with the lingual branch of the fifth, afford 

 a ready explanation of this fact. 



The functions of the sublingual have already been so fully considered under the head 

 of deglutition, that they need not be discussed elaborately in this connection. We shall 

 here simply state the phenomena which follow stimulation of the nerve and the division 

 of both nerves in living animals. 



