The genioglossus is one of the paired extrinsic muscles of the

tongue The tongue is a Muscle, muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper s ...

. It is a fan-shaped muscle that comprises the bulk of the body of the tongue. It arises from the mental spine of the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

; it inserts onto the hyoid bone, and the bottom of the tongue. It is innervated by the hypoglossal nerve (cranial nerve XII). The genioglossus is the major muscle responsible for protruding (or sticking out) the tongue.

Structure

Genioglossus is the fan-shaped extrinsic tongue muscle that forms the majority of the body of the

. The muscle is paired, having a left and right portion, which are divided at the midline of the tongue by a septum made of connective tissue.

Origin

The large part of the muscle arises from the mental spine of the

, but some fibers originate directly from the hyoid bone and connect vertically to the tongue.

Insertion

Its insertions are the hyoid bone and the bottom of the tongue.

Innervation

The genioglossus is innervated by the hypoglossal nerve, as are all muscles of the tongue except for the palatoglossus.

Blood supply

Blood is supplied to the sublingual branch of the lingual artery, a branch of the external carotid artery.

Function

The left and right genioglossus muscles protrude the tongue (anteriorly, out of the mouth) and deviate it towards the opposite side. When acting together, the muscles protrude the tongue directly forward and depress the center of the tongue at its back.

Clinical significance

Contraction of the genioglossus stabilizes and enlarges the portion of the upper airway that is most vulnerable to collapse. Relaxation of the genioglossus and geniohyoideus muscles, especially during REM sleep, is implicated in

obstructive sleep apnea Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder and is characterized by recurrent episodes of complete or partial airway obstruction, obstruction of the respiratory tract#Upper respiratory tract, upper airway lea ...

. Given this connection, the mandible can be pulled forward to maximise the airway space, and prevent the tongue from sinking backwards under

anaesthesia Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prev ...

and obstructing the airway. The genioglossus is often used as a proxy to test the function of the hypoglossal nerve (CN XII), by asking a patient to stick out their tongue. Peripheral damage to the hypoglossal nerve can result in deviation of the tongue to the damaged side. If the tongue protrudes directly forward instead of deviating to either side, then the hypoglossal nerves are likely not injured.

History

The name derives from the Greek words γένειον (''geneion'') meaning "

chin The chin is the forward pointed part of the anterior mandible (List_of_human_anatomical_regions#Regions, mental region) below the lower lip. A fully developed human skull has a chin of between 0.7 cm and 1.1 cm. Evolution The presence of a we ...

", and γλῶσσα (''glōssa'') meaning "tongue." The earliest recorded mention is by Helkiah Crooke in the early seventeenth century.

Other animals

The canine genioglossus muscle has been divided into horizontal and oblique compartments.

References

External links

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Frontal section
{{Authority control Muscles of the head and neck Tongue