The geniohyoid muscle is a narrow
muscle situated superior to the medial border of the
mylohyoid muscle
The mylohyoid muscle or diaphragma oris is a paired muscle of the neck. It runs from the mandible to the hyoid bone, forming the floor of the oral cavity of the mouth. It is named after its two attachments near the molar teeth. It forms the fl ...
. 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 inferior
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. ...
, on the back of the
mandibular symphysis, and runs backward and slightly downward, to be inserted into the anterior surface of the body of the
hyoid bone.
It lies in contact with its fellow of the opposite side. It thus belongs to the
suprahyoid muscles. The muscle is supplied by branches 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 ...
.
Innervation
The geniohyoid muscle is innervated by fibres from the
first cervical spinal nerve travelling alongside 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 ...
.
Although the first three cervical nerves give rise to the
ansa cervicalis
The ansa cervicalis (or ansa hypoglossi in older literature) is a loop of nerves that are part of the cervical plexus. It lies superficial to the internal jugular vein in the carotid triangle. Its name means "handle of the neck" in Latin.
Bran ...
, the geniohyoid muscle is said to be innervated by the first cervical nerve, as some of its efferent fibers do not contribute to ansa cervicalis.
Variations
It may be blended with the one on opposite side or double; slips to
greater cornu of hyoid bone and
genioglossus occur.
Function
The geniohyoid muscle brings the
hyoid bone forward and upwards.
This dilates the
upper airway, assisting
respiration
Respiration may refer to:
Biology
* Cellular respiration, the process in which nutrients are converted into useful energy in a cell
** Anaerobic respiration, cellular respiration without oxygen
** Maintenance respiration, the amount of cellul ...
.
During the first act of
deglutition, when the mass of food is being driven from the mouth into the pharynx, the hyoid bone, and with it the tongue, is carried upward and forward by the anterior bellies of the Digastrici, the Mylohyoidei, and Geniohyoidei. It also assists in depressing the mandible
History
The inclined position of the geniohyoid muscle has been contrasted to the horizontal position in
neanderthal
Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the ...
s.
Additional images
File:Gray186.png, Illustration of the hyoid bone showing the insertion point of the geniohyoid muscle
File:Gray994.png, Sagittal section of nose mouth, pharynx, and larynx.
File:Slide1ss.JPG, Geniohyoid muscle
File:Slide4ss.JPG, Geniohyoid muscle
File:Slide9ss.JPG, Geniohyoid muscle
See also
References
External links
*
*
Frontal section
{{Authority control
Muscles of the head and neck
Suprahyoid muscles