The frontal nerve, also known as the supraorbital nerve, is a cranial nerve that supplies sensory innervation to the forehead and scalp. It is a branch of the ophthalmic division of the trigeminal nerve (CN V1) and is responsible for transmitting sensory information from the skin of the forehead, scalp, and eyebrows to the brain.
Structure
The frontal nerve is a small, thin nerve that arises from the ophthalmic division of the trigeminal nerve (CN V1). It originates from the superior orbital fissure, a small opening in the skull located above the eye socket. From there, the nerve travels through the orbital cavity and exits the skull through the supraorbital notch or foramen, located just above the eyebrows.
Once it exits the skull, the frontal nerve divides into two branches: the medial and lateral branches. The medial branch supplies sensory innervation to the skin of the midline forehead and the bridge of the nose. The lateral branch supplies sensory innervation to the skin of the lateral forehead and the eyebrows.
Location
The frontal nerve is located in the orbital cavity of the skull, within the eye socket. It originates from the superior orbital fissure and exits the skull through the supraorbital notch or foramen. From there, it travels through the skin of the forehead, scalp, and eyebrows, innervating these areas with sensory fibers.
Function
The primary function of the frontal nerve is to provide sensory innervation to the skin of the forehead, scalp, and eyebrows. It transmits sensory information from these areas to the brain, allowing us to perceive touch, temperature, and pain in these regions.
The frontal nerve is also responsible for the reflexive contraction of the frontalis muscle, which raises the eyebrows and wrinkles the forehead. This reflex helps protect the eyes from bright light or foreign objects.
Clinical significance
Injury or damage to the frontal nerve can result in sensory deficits in the forehead, scalp, and eyebrows. This can cause numbness or tingling sensations in these areas and may make it difficult to perceive touch or temperature changes.
Damage to the frontal nerve can also cause weakness or paralysis of the frontalis muscle, resulting in a lack of movement in the eyebrows and forehead. This can affect facial expressions and may cause problems with eye protection reflexes.
The frontal nerve is also a common site of neuralgia, a type of chronic pain disorder that affects the nerves. Neuralgia of the frontal nerve, also known as supraorbital neuralgia or trigeminal neuralgia, can cause severe, intermittent pain in the forehead, scalp, and eyebrows.
In some cases, the frontal nerve can be injured during surgery, particularly during procedures involving the skull or eye socket. It is important for surgeons to be aware of the location and function of the frontal nerve to minimize the risk of injury.
