Question

multiple choice question

the two parts of the occipitofrontalis, the frontalis and the occipitalis, act together to perform which action?

elevation of the eyebrows
elevation of the eyelids to open the eye
retraction of scalp
compression of the cheek

Explanation:

Identify the muscle structure

Using the Occipitofrontalis Muscle knowledge point, we recognize that the occipitofrontalis is a bipartite muscle of the scalp consisting of the frontal belly (frontalis) anteriorly and the occipital belly (occipitalis) posteriorly, connected by a broad tendon called the epicranial aponeurosis.

Analyze the combined action

Using the Occipital Belly Action knowledge point, we evaluate how these two bellies interact. When the occipital belly contracts, it pulls the epicranial aponeurosis posteriorly, anchoring it. This allows the frontal belly to contract effectively from a fixed posterior position, pulling the skin of the forehead upward to elevate the eyebrows and wrinkle the forehead. Thus, acting together, their primary coordinated action is the elevation of the eyebrows.

Evaluate the incorrect options

• Elevation of the eyelids to open the eye: This action is performed by the levator palpebrae superioris muscle, not the occipitofrontalis.
• Retraction of scalp: While the occipital belly alone retracts the scalp, acting together with the frontalis stabilizes the aponeurosis to primarily move the forehead and eyebrows.
• Compression of the cheek: This action is performed by the buccinator muscle.

Answer:

• Elevation of the eyebrows (Correct answer)
• Elevation of the eyelids to open the eye
• Retraction of scalp
• Compression of the cheek