1066 ORGANS OF SPECIAL SENSE 



superior constrictor of the pharynx, all of which are described elsewhere (see pp. 

 344, 1078, and 1085). 



The intrinsic muscles. The longitudinalis superior (fig. 761) is a superficial 

 longitudinal stratum extending from the base to the apex of the tongue, immediately 

 beneath the mucosa of the dorsum, to which many of its fibres are attached. The 

 longitudinalis inferior (fig. 761) is composed of two muscle-bands extending from 

 base to apex on the inferior surface of the tongue, and is situated between the hyo- 

 glossus and the genio-glossus, some of its fibres near the apex mixing with the stylo- 

 glossus, while dorsally some are attached to the hyoid bone. The transversus 

 linguae (fig. 761) consists of fibres which pass transversely, and is situated between 

 the superior and inferior longitudinal muscles. The fibres arise from, or pass through, 

 the septum linguae, and are attached to the mucosa of the dorsum and lateral mar- 

 gins of the tongue. The verticalis linguae (fig. 761) is composed of fibres which 

 pass from the mucosa of the dorsum to the mucosa of the inferior surface of the 

 tongue, interlacing with those of the other intrinsic and extrinsic muscles. 



Vessels and nerves. The lingual arteries furnish the principal blood-supply (p. 520, fig. 

 410). The lingual veins (p. 664) carry the blood from the tongue to the internal jugular. The 

 lymphatics from the ventral portion empty into the siibmaxillary lymph-nodes and from the pos- 

 terior portion into the deep cervical nodes. The nerves are motor and sensory (fig. 763). The 

 hypoglossal nerve supplies the intrinsic* and all the extrinsic muscles of the tongue except the 

 glosso-palatinus (palato-glossus) , which is supplied from the pharyngeal plexus (p. 984). The 

 sensory nerves are: the lingual nerve, a branch of the mandihular division of the fifth, which, 

 after joining with the chorda tympani from the seventh, is distributed to the anterior two-thirds 

 of the tongue (p. 969); the lingual branches of the glosso-pharyngeal, which are distributed 

 to the pharyngeal third of the tongue, including the valltite papilla; (p. 981); and the superior 

 laryngeal branch of the vagus, which supplies a small area near the epiglottis. 



The development of the tongue. The tongue arises from two distinct origins, one of which 

 is paired. The anterior unpaired portion appears as a thickening in the floor of the mouth op- 

 posite the ventral ends of the first branchial arches, while the posterior paired portions are formed 

 from a thickening over the ventral end of the second branchial arch of each side. The anterior 

 portion is received posteriorly between the diverging limbs of the posterior portion, and a fusion 

 of both portions occurs along a V-shaped line, situated immediately behind the line of the vallate 

 papillae, its apex being indicated by the foramen csecum. 



