THE HYPOGLOSSAL NERVE. 625 



CHORDA TYJIPAXI. Joining the lingual nerve close below its 

 origin (p. 618), the chorda tympani accompanies that trunk, but can destination. 

 be easily separated from it nearly as far as the tongue. Beyond 

 that point its fibres are mixed with those of the lingual nerve. Near 

 the submaxillary gland, an offset is sent to the submaxillary 

 ganglion. 



The HYPOGLOSSAL or TWELFTH nerve in the submaxillary region Twelfth 

 is directed forwards across the lower part of the hyo-glossus muscle, hyoldbone? 

 and under cover of the mylo-hyoid. At the anterior border of the 

 hyo-glossus it enters the fibres of the genio-glossus, spreading out 

 and dividing into numerous branches as it disappears. 



Branches. While resting on the hyo-glossus, the twelfth nerve its branches 

 furnishes offsets to the stylo-glossus, hyo-glossus and genio-hyoid* muscles 

 muscles, as well as one or two communicating filaments to the ofton s ue - 

 lingual nerve. Its terminal branches, within the genio-glossus, 

 supply that muscle and the intrinsic muscles of the tongue. The 

 lingual branches are long and slender, and some of them may be 

 traced forwards to the tip of the tongue. 



The GLOSSO-PHARYNGEAL nerve (fig. 224, 4 ), appearing between the 

 two carotid arteries, courses forwards over the stylo-pharyngeus, and 

 ends under the hyo-glossus in branches for the tongue. (See the 



DISSECTION OF THE TONGUE, p. 688). 



The duct of the submaxillary gland (fig. 224, 3 ), Wharton's duct, Wharton's 

 issues from the deep part of the glandular mass turning round the 

 border of the mylo-hyoid muscle. About two inches in length, it is 

 directed upwards and forwards on the hyo-glossus muscle, and over 

 the lingual nerve, to open on the centre of an eminence by the side opens by 

 of the fraenum linguae : the opening in the mouth will be seen if a 

 bristle be passed along the duct. The deep part of the submaxillary 

 gland extends along the side of the duct, reaching, in some instances, 

 the sublingual gland. 



The SUBLINGUAL GLAND (fig. 224, N) is an almond-shaped body g u bii n gual 

 with its longest diameter, which measures about an inch and a half, g land 

 directed from before backwards. It lies beneath the fore part of the 

 tongue, between the genio-glossus muscle and the lower jaw, and 

 resting on the mylo-hyoid. Its upper border is covered by mucous forms a 

 membrane, which is raised into a fold along the floor of the mouth 

 over the gland ; and its inner end touches the one of the opposite tongue, 

 side behind the symphysis of the jaw. 



The gland consists of from ten to twenty small masses, each of and is a 

 which has a separate duct. The ducts (ducts of Rivinus) open for 

 the most part on the sublingual mucous fold, but some of them join 

 the submaxillary duct, and one larger tube (duct of Bartholin), which 

 is, however, frequently wanting, springs from the deeper part of the 

 gland and runs forward to end either in common with, or close to, 

 the duct of Wharton. 



* The branch to the genio-hyoid muscle is composed of fibres derived from 

 the cervical nerves. Compare note on p. 602. 



D.A. S S 



