THE MUSCLES OF THE TONGUE. 387 
- The palato-glossus is a thin sheet of muscular fibres arising from the under 
surface of the soft palate, where it is continuous with fibres of the opposite muscle. 
It passes downwards in the anterior pillar of the fauces, and spreads out, to be in- 
_serted into the sides of the tongue, blending with the stylo-glossus and the deep 
transverse fibres of the tongue. “The muscle is placed directly beneath the mucous 
membrane of the soft palate and tongue. 
Intrinsic Muscles of the Tongue.—Besides receiving the fibres of insertion 
of the extrinsic muscles, the substance of the tongue is composed of four intrinsic 
muscles on either side, two in the sagittal plane, the superior and inferior lnguales ; 
two in the coronal plane, the transverse and vertical fibres. 
The superior lingualis muscle extends from base to tip of the tongue, placed on 
its dorsum immediately under the mucous membrane, into which many of its fibres 
are inserted. 
The inferior lingualis is a cylindrical band of muscular fibres occupying the under 
part of the organ on each side, in the interval between the genio-hyo-glossus and the 
_hyo-glossus muscles. Posteriorly some of its fibres extend to the hyoid bone. 
The transverse fibres arise from the median raphe, and radiate outwards to the 
dorsum and sides of the tongue, decussating with the extrinsic muscles and the 
fibres of the vertical muscle. They occupy the substance of the tongue between the 
superior and inferior linguales. 
The so-called vertical fibres arise from the dorsal surface of the tongue, and 
sweep downwards and outwards to its sides, intermingled with the fibres of the 
previous muscle and the insertions of the extrinsic muscles. These two muscles 
form a very considerable part of the total muscular substance of the organ. 
NERVE SUPPLY. 
The muscles of the hyoid bone and of the tongue are for the most part supplied by the ansa 
cervicalis (C. 1. 2. 3.) and by the hypoglossal nerve. <A few of the muscles are supplied by the 
trigeminal, facial, and spinal accessory nerves. 
Muscles. | Nerves. Origin. | 
Omo-hyoid . : : zi | | 
Sterno-hyoid ; ; : ; . | Ansa cervicalis . : : Chi & 
Sterno-thyroid . : ; | 
Thyro-hyoid ; f ny ap 
Genio-hyoid : ; : : : | | ee: 
Genio-hyo-glossus ns | 
yc ales mae - Hypoglossal : J 
Stylo- glossus | | XII 
Intrinsic muscles of tongue Al \| 
Palato-glossus | Pharyngeal plexus . ; Ol: 
Mylo-hyoid || Mylo-hyoid branch of in- | Vv 
eee belly: ; | | ferior dental nerve -\f i 
Posterior belly ( F ; 1) Wack. 
Sucileratl) eo weve ballkewe eee Vil 
ACTIONS. 
These muscles of the neck have a complexity of muscular action, owing to their numerous 
attachments to more or less movable points. The movements for which they are responsible in 
whole or part are (1) movements of the hyoid bone in mastication and deglutition, (2) movements 
of the thyroid cartilage, (8) movements of the tongue, (4) movements of the head, (5) movements 
of the shoulder, and 6) respiration. 
| (1) Movements of the Hyoid Bone.—The hyoid bone is elevated or depressed, and moved 
forwards or backwards along with the lower jaw and tongue, in speech, mastication, and 
swallowing. 
