Anatomy

Origin

It arises by a short tendon from the superior mental spine on the inner surface of the symphysis menti, immediately above the Geniohyoideus, and from this point spreads out in a fan-like form. 

Insertion

The inferior fibers extend downward, to be attached by a thin aponeurosis to the upper part of the body of the hyoid bone, a few passing between the Hyoglossus and Chondroglossus to blend with the Constrictores pharyngis; the middle fibers pass backward, and the superior ones upward and forward, to enter the whole length of the under surface of the tongue, from the root to the apex.    

Nerve

Hypoglossal nerve (CN XII).

Actions

Acting blaterally:

• Posterior fibers: draw the root of the tongue forward, and protrude the apex from the mouth.
• Anterior fibers: draw the tongue back into the mouth.

Whole muscle action: The two muscles acting in their entirety draw the tongue downward, so as to make its superior surface concave from side to side, forming a channel along which fluids may pass toward the pharynx, as in sucking.