Orbicularis Oris muscle action is?

Orbicularis Oris muscle action is?

• A. Action: closes mouth; kissing muscle
• B. Origin: maxilla and mandible
• C. Insertion: lips
• D. Insertion: skin on lateral sides of the mouth

Answer: (A)

The key idea is that the orbicularis oris acts as a circular muscle around the mouth, functioning as a sphincter. When it contracts, it closes the oral opening and tightens the lips, which is exactly what you do when you kiss or purse your lips. That functional action—closing the mouth and shaping the lips—best captures its role, making it the most correct description. The other options describe where the muscle originates or inserts, which are not the primary features that define what the orbicularis oris does; it doesn’t originate from bone in the way jaw muscles do, and while it inserts into the lips (and surrounding skin/mucosa), the crucial point for its identity is its lip-closing action.

The key idea is that the orbicularis oris acts as a circular muscle around the mouth, functioning as a sphincter. When it contracts, it closes the oral opening and tightens the lips, which is exactly what you do when you kiss or purse your lips. That functional action—closing the mouth and shaping the lips—best captures its role, making it the most correct description. The other options describe where the muscle originates or inserts, which are not the primary features that define what the orbicularis oris does; it doesn’t originate from bone in the way jaw muscles do, and while it inserts into the lips (and surrounding skin/mucosa), the crucial point for its identity is its lip-closing action.