196 HEAD AND NECK 



by two short branches, which enter its upper border, and are 

 separated by a distinct interval. The posterior connecting 

 twig is frequently replaced by two or three filaments, which 

 form the sensory and secretory roots of the ganglion, whilst 

 the anterior connecting branch must be looked upon as a 

 twig given by the ganglion to the lingual nerve. 



Like the other ganglia developed in connection with the 

 branches of the trigeminal nerve, the submaxillary ganglion has 

 three roots viz., (i) a sensory root from the lingual nerve ; (2) 

 a secretory root from the chorda tympani ; and (3) a sympathetic 

 root from the plexus around the external maxillary artery. 



From its lower border several minute twigs proceed ; they 

 are distributed (i) to the submaxillary gland and duct; (2) 

 to the sublingual gland, from the branch given by the 

 ganglion to the lingual nerve ; and (3) to the mucous 

 membrane of the mouth. 



Nervus Hypoglossus. The hypoglossal nerve has been 

 traced, in the dissection of the anterior triangle, to the point 

 where it disappears under cover of the mylo-hyoid muscle 

 (p. 130). It is now seen passing forwards upon the 

 hyoglossus muscle, above the hyoid bone and below the level 

 of the deep part of the submaxillary gland. At the anterior 

 border of the hyoglossus it gains the surface of the genio- 

 glossus muscle, into the substance of which it sinks ; and 

 finally it breaks up into branches which supply the muscular 

 substance of the tongue. Upon the hyoglossus muscle it 

 is accompanied by the lingual vein. 



The branches which spring from the hypoglossal nerve in 

 the region of the floor of the mouth are very numerous, and 

 are distributed entirely to muscles. It supplies (i)thestylo- 

 glossus j (2) the hyoglossus ; (3) the genio-glossus ; (4) the 

 genio-hyoid ; and (5) the intrinsic muscles of the tongue. 



In addition, it communicates freely with the lingual 

 nerve. The more apparent of the connections take the form 

 of one or more loops which lie on the lateral surface of the 

 anterior part of the hyoglossus. Other communications with 

 the lingual nerve are effected in the substance of the tongue. 



Dissection. The hyoglossus should now be carefully de- 

 tached from the hyoid bone, and thrown upwards towards the 

 tongue, but the structures which lie upon the superficial surface 

 of the muscle need not be divided. By the reflection of the 

 hyoglossus muscle the following structures will be fully dis- 

 played, and must be cleaned (i) the profunda linguae artery 



