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.

[1] The large part of the muscle arises from the mental spine of the mandible,[2][3] but some fibers originate directly from the hyoid bone and connect vertically to the tongue.

[2][1] The left and right genioglossus muscles protrude the tongue (anteriorly, out of the mouth) and deviate it towards the opposite side.

[2] Contraction of the genioglossus stabilizes and enlarges the portion of the upper airway that is most vulnerable to collapse.

[2] 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.