Muscles of Tongue

Structure and/or Key Features

The muscles of the tongue consist primarily of two groups of muscles, the extrinsic and intrinsic muscles of the tongue. The extrinsic muscles attach the tongue to external regions and include the:

—genioglossus muscle;

—hyoglossus muscle;

—chondroglossus muscle;

—styloglossus muscle;

—palatoglossus muscle.

The genioglossus muscle is attached to the superior mental spine of the mandible. From here, it extends in a superoposterior direction and attaches to the superior surface of the hyoid body and along the length of the ventral tongue from the root to the apex. The right and left genioglossus muscles are separated by the lingual septum posteriorly, but blend with each other anteriorly.

The hyoglossus is a thin, quadrilateral sheet of muscle which arises from the greater horn and body of the hyoid body. It moves upwards to insert into the side of the tongue, passing between the lateral styloglossus and medial inferior longitudinal muscles. The chondroglossus muscle may be described as a portion of the hyoglossus muscle, originating from the lesser horn of the hyoid bone and blends with the intrinsic muscles of the tongue between the hyoglossus and genioglossus muscles.

The styloglossus arises from the styloid processes of the temporal bone, as well as from the styloid segment of the stylomandibular ligament. The muscle passes down and splits it divides into longitudinal and oblique parts. The longitudinal part enters the tongue posterolaterally and blends with the inferior longitudinal lingual muscle. The oblique part overlaps with the hyoglossus muscle and decussates with it.

The palatoglossus is also a muscle of the soft palate. It originates from the palatine aponeurosis, and moves downwards, passing over the palatine tonsil to insert into the side of the tongue, with some of its fibers inserting deeply to mesh with the intrinsic transverse muscle. The palatoglossus is unique in that it is innervated by the pharyngeal plexus (accessory nerve CN XI). It is the only tongue muscle which is not innervated by the hypoglossal nerve.

The intrinsic muscles attach within the tongue and change its shape. They include the:

—superior longitudinal lingual muscle;

—inferior longitudinal lingual muscle;

—transversus linguae muscle;

—verticalis linguae muscle.

The transversus linguae muscle pass from the fibrous septum, towards the lingual margin. It inserts into the submucosal fibrous tissues there and blend in with the palatopharyngeus muscle.

The verticalis linguae muscle runs from the dorsal aspect of the tongue extend to the lateral margins of the ventral portions of the tongue.

The superior longitudinal muscle sits just below the mucosa of the dorsal aspect of the tongue, forming a thin layer across the dorsum of the tongue. It extends forwards from the epiglottic region to the tip of the tongue anteriorly and from the lingual septum medially to the lateral lingual margins.

Function

The extrinsic muscle of the tongue work to alter the position of the tongue. The genioglossus muscle enables the tongue to stick out of the mouth. Synchronized bilateral movement of both muscles functions to lower the central part of the tongue, while individual genioglossal movements cause the tongue to move to the opposing side. The hyoglossus muscle depresses the tongue, while the styloglossus muscle allows the tongue to be brought back and upwards. The palatoglossus muscle closes off the oral cavity from the oropharynx by elevating the tongue root to make contact with the palatoglossal arch.

The intrinsic muscles of the tongue are responsible for changing its shape, movements required for deglutition and phonation.

List of Clinical Correlates

—Dysarthria

References

Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.