Which muscle is activated by myofunctional exercises of successive movements of the lip commissures?

Which muscle is activated by myofunctional exercises of successive movements of the lip commissures?

• A. External fascicle of the orbicularis oris muscle
• B. Internal fascicle of the orbicularis oris muscle
• C. Buccinator muscles
• D. External pterygoid muscles

Answer: (D)

When you train movements of the lip corners, the muscle that does the primary work is the orbicularis oris, which encircles the mouth like a sphincter. The external fascicles form the outer border of the lips and are the main part responsible for shaping and repositioning the corners during these exercises. They contract to tighten, purse, or move the lips as you alternate the position of the commissures. The internal fascicles of orbicularis oris play a role in lip compression, but the noticeable movement of the lip corners comes most from the superficial, external fibers. The buccinator supports cheek tone but isn’t the primary driver of commissure movements, and the lateral pterygoid group governs jaw movements rather than lip corner control. So the external fascicle of the orbicularis oris is the muscle most engaged by successive lip-commissure movements.

When you train movements of the lip corners, the muscle that does the primary work is the orbicularis oris, which encircles the mouth like a sphincter. The external fascicles form the outer border of the lips and are the main part responsible for shaping and repositioning the corners during these exercises. They contract to tighten, purse, or move the lips as you alternate the position of the commissures. The internal fascicles of orbicularis oris play a role in lip compression, but the noticeable movement of the lip corners comes most from the superficial, external fibers. The buccinator supports cheek tone but isn’t the primary driver of commissure movements, and the lateral pterygoid group governs jaw movements rather than lip corner control. So the external fascicle of the orbicularis oris is the muscle most engaged by successive lip-commissure movements.