Final answer:
The orbicularis oculi is a muscle that originates from the frontal and maxillary bones and ligaments around the orbit, inserting into the skin around the eye margins. Its action is to close the eyelids and it plays a key role in the corneal reflex.
Step-by-step explanation:
The orbicularis oculi muscle is a circular muscle whose primary action is to close the eyelids. It originates from the frontal and maxillary bones and parts of the ligaments around the orbit, and it inserts into the skin around the margins of the orbit and the upper and lower eyelids. This muscle plays a crucial role in facial expressions, such as blinking and winking, and is also an important component in the corneal reflex, which protects the eye from injuries.
The action of the orbicularis oculi is to close the eyelids, either voluntarily or involuntarily as part of the corneal reflex. This reflex is triggered when the cornea is stimulated by a tactile stimulus, causing the orbicularis oculi to contract and resulting in a blink to protect the eye. The muscle is innervated by the facial nerve, which carries the motor response during this reflex.