180 NERVOUS SYSTEM. 



neck to the sterno-hyoid, sterno-thyroid, and omo-hyoid 

 muscles. From its relations with important vessels and 

 nerves, this branch possesses considerable surgical interest. 



The thyro-hyoid branch is distributed to the muscle of 

 the same name. 



The other branches are distributed to the stylo-glossus, 

 hyo-glossus, genio-hyoid, and genio-hyo-glossus muscles, their 

 terminal filaments going to the intrinsic muscles of the tongue. 



It is thus seen that the sublingual nerve is distributed to 

 all of the muscles in the infra-hyoid region, the action of 

 which is to depress the larynx and the hyoid bone after 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 in another volume. 1 



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 no 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 sublingual is necessarily 

 exposed, Longet has irritated the roots in the dog without 

 any evidence of pain on the part of the animal. 2 In the dog, 

 Yulpian has constantly found the small ganglionic root, 3 

 which we have already mentioned as exceptional in the hu- 

 man subject. Such experiments, taken in connection with 

 the anatomical characters of the nerve, render it almost cer- 



1 See vol. ii., Digestion, p. 189, el seq. 



2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 584. 



8 VULPIAN, Sur la racine posterieure ou ganglionnaire du nerf hypoglosse. 

 Journal de la physiologic, Paris, 1862, tome v., p. 7. 



