A broad, thin, fan-shaped muscle placed in the centre of the tongue. Some of its fibres pass downwards to the tip, others to the centre, and a third portion to the root of the tongue.

Origin. - From the inner surface of the lower jaw, near the symphysis, or union of the two branches.

Insertion. - Into the under surface of the mucous membrane, along its middle, from the tip to the root.

Action. - The lower portion of the muscle when contracting would draw the tongue into the mouth, the upper division would cause it to protrude. The central part would pull it away from the roof.