Which nerve innervates the frontalis muscle and is therefore responsible for frontalis activation during facial movement?

Which nerve innervates the frontalis muscle and is therefore responsible for frontalis activation during facial movement?

• A. Facial nerve
• B. Spinal accessory nerve
• C. Trigeminal nerve
• D. Hypoglossal nerve

Answer: (A)

The frontalis muscle is controlled by the facial nerve (cranial nerve VII). Its temporal branch innervates the frontalis, allowing forehead movements such as raising the eyebrows during facial expressions. The other nerves don’t supply this muscle: the spinal accessory nerve serves neck and shoulder muscles, the trigeminal nerve mainly handles muscles of mastication and facial sensation, and the hypoglossal nerve controls tongue movements. Thus, the nerve responsible for frontalis activation is the facial nerve.

The frontalis muscle is controlled by the facial nerve (cranial nerve VII). Its temporal branch innervates the frontalis, allowing forehead movements such as raising the eyebrows during facial expressions. The other nerves don’t supply this muscle: the spinal accessory nerve serves neck and shoulder muscles, the trigeminal nerve mainly handles muscles of mastication and facial sensation, and the hypoglossal nerve controls tongue movements. Thus, the nerve responsible for frontalis activation is the facial nerve.