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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 taste b ...
. 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
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 taste b ...
. 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 tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
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 ver ...
and the bottom of the tongue. The genioglossus is innervated by the hypoglossal nerve, as are all muscles of the tongue except for the
palatoglossus The palatoglossus or palatoglossal muscle is a muscle of the soft palate and extrinsic muscle of the tongue. Its surface is covered by oral mucosa and forms the visible palatoglossal arch. Structure Palatoglossus arises from the palatine aponeur ...
. 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 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 The geniohyoid muscle is a narrow muscle situated superior to the medial border of the mylohyoid muscle. It is named for its passage from the chin ("genio-" is a standard prefix for "chin") to the hyoid bone. Structure It arises from the inferi ...
muscles, especially during REM sleep, is implicated in obstructive sleep apnea. 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 on ...
", and γλῶσσα (''glōssa'') meaning "tongue." The earliest recorded mention is by Helkiah Crooke in the early seventeenth century.


References


External links

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