The genioglossus is one of the paired extrinsic muscles of the

tongue The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by tas ...

. 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

. It arises from the

mental spine A mental spine is a small projection of bone on the posterior aspect of the mandible in the midline. There are usually four mental spines: two superior and two inferior. Collectively they are also known as the ''genial tubercle'',"Genial tubercle. ...

of the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bon ...

and its insertions are the

hyoid bone The hyoid bone (lingual bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies between the base of the mandible and the third cervical vert ...

and the bottom of the tongue. The genioglossus is innervated by the

hypoglossal nerve The hypoglossal nerve, also known as the twelfth cranial nerve, cranial nerve XII, or simply CN XII, is a cranial nerve that innervates all the extrinsic and intrinsic muscles of the tongue except for the palatoglossus, which is innervated by ...

, as are all muscles of the tongue except for the palatoglossus. Blood is supplied to the sublingual branch of the

lingual artery The lingual artery arises from the external carotid artery between the superior thyroid artery and facial artery. It can be located easily in the tongue. Structure The lingual artery first branches off from the external carotid artery. It runs ob ...

, a branch of the

external carotid artery The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external and internal carotid artery. External carotid artery supplies blood to the face and neck. Structure ...

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

Function

The left and right genioglossus muscles protrude the tongue and deviate it towards the opposite side. When acting together, the muscles 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 Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream ...

, 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 obstruction of the upper airway leading to reduced or absent breathing during sleep. These episo ...

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

anaesthesia Anesthesia 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 prevention of pain), paralysis (muscle relaxation), a ...

and obstructing the airway. The genioglossus is often used as a proxy to test the function of the hypoglossal nerve, 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.

History

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

chin The chin is the forward pointed part of the anterior mandible ( 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 well-developed chin is considered to be one ...

", and γλῶσσα (''glōssa'') meaning "tongue." The earliest recorded mention is by

Helkiah Crooke Helkiah Crooke (1576 – 1648) was Court physician to King James I of England. He is best remembered for his textbook on anatomy, ''Mikrokosmographia, a Description of the Body of Man''. He was the first qualified doctor to be appointed Keeper ...

in the early seventeenth century.

References

External links

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