The muscles of tongue can be divided into intrinsic and extrinsic groups.
The intrinsic muscles lie entirely within the tongue, while the extrinsic muscles attach the tongue to other structures.
The extrinsic muscles reposition the tongue, while the intrinsic muscles alter the shape of the tongue for talking and swallowing.
Extrinsic tongue muscles, by definition, originate from structures outside the tongue and insert into the tongue. The four paired extrinsic muscles protrude, retract, depress, and elevate the tongue:
Four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. These muscles alter the shape of the tongue by: lengthening and shortening it, curling and uncurling its apex and edges, and flattening and rounding its surface: