Muscle · Neck

Mylohyoid

Musculus mylohyoideus

The muscular floor of the mouth — a flat triangular sheet slung like a hammock between the two halves of the lower jaw, closing off the space beneath the tongue. Its two halves meet in the midline not at bone but at a fibrous seam running back from the chin to the hyoid, which is what lets the pair act as one continuous diaphragm rather than two muscles. Contract it and the whole floor of the mouth rises, squeezing the tongue up against the palate to drive food backwards; with the jaw fixed it lifts the hyoid, and with the hyoid fixed it helps open the jaw. It shares its nerve supply with the front belly of the digastric — both come from the trigeminal, a fingerprint of their shared origin in the first pharyngeal arch, while every other suprahyoid muscle is supplied from elsewhere.