The supratrochlear nerve is a small nerve that is part of the facial nerve (cranial nerve VII) system. It is responsible for innervating the skin on the forehead and upper eyelid, as well as providing sensory input to the cornea. In this article, we will explore the structure, location, function, and clinical significance of the supratrochlear nerve.
Structure
The supratrochlear nerve is a branch of the ophthalmic nerve (a division of the trigeminal nerve), which is the main sensory nerve of the face. The ophthalmic nerve itself arises from the trigeminal ganglion, a collection of nerve cell bodies located within the skull.
The supratrochlear nerve is a small, thin nerve that emerges from the ophthalmic nerve just above the trochlea, a small pulley-like structure located on the inner corner of the eye. It then travels upwards and laterally across the forehead, passing over the supraorbital margin (the bony ridge above the eye socket) and entering the skin of the forehead and upper eyelid.
Location
The supratrochlear nerve is located in the front of the head, running from the inner corner of the eye across the forehead and upper eyelid. It can be easily palpated by pressing on the skin just above the inner corner of the eye, near the bridge of the nose.
Function
The primary function of the supratrochlear nerve is to innervate the skin on the forehead and upper eyelid, providing sensory input to these areas. This includes information about touch, temperature, and pain.
In addition to innervating the skin, the supratrochlear nerve also provides sensory input to the cornea, the clear outer layer of the eye. The cornea is responsible for focusing light onto the retina, and the supratrochlear nerve helps to detect any changes in the shape of the cornea that may affect vision.
Clinical Significance
The supratrochlear nerve can be affected by various conditions and injuries, which can lead to sensory deficits or pain in the affected areas. Some common causes of supratrochlear nerve dysfunction include:
- Trauma: A blow to the head or eye socket can damage the supratrochlear nerve, leading to sensory deficits or pain in the affected areas.
- Infection: Inflammation or infection of the nerve can cause pain or numbness in the forehead and upper eyelid.
- Tumors: Tumors in the head or neck can compress or damage the supratrochlear nerve, leading to sensory deficits or pain.
- Neurological disorders: Certain neurological disorders, such as multiple sclerosis or Bell’s palsy, can affect the supratrochlear nerve and cause sensory deficits or pain.
In cases of supratrochlear nerve dysfunction, treatment may involve medications to reduce inflammation or pain, physical therapy to stimulate the nerve and improve function, or surgery to remove the cause of the dysfunction (such as a tumor).
