Orbicularis Oculi performs which action?

• A. Origin: medial margin of orbit
• B. Insertion: skin around eyelids
• C. Insertion: galea aponeurotica
• D. Action: closes, blinks and squints eyes

Answer: (D)

The action of the orbicularis oculi is to close the eyelids. It forms a circular muscle around the eye, acting like a sphincter. When it contracts, it pulls the eyelids together, which enables blinking (gentle closure) and also allows for tighter closure when squinting. The muscle has a palpebral part for soft blinking and an orbital part for stronger closure, which is why its primary function is eyelid closure in both blinking and squinting. The other details describe where the muscle attaches (origin at the medial margin of the orbit, insertion around the eyelids) or involve a different muscle group (galea aponeurotica relates to frontalis), but they don’t define the action itself.