Structure
The external nasal nerve is a branch of the infratrochlear nerve, which is itself a branch of the ophthalmic division of the trigeminal nerve (CN V1). The infratrochlear nerve arises from the orbital apex, passes through the lacrimal gland, and divides into the external nasal and internal nasal branches. The external nasal nerve supplies sensory innervation to the skin of the lateral aspect of the nose, including the alar cartilage and the alar groove.
Where is External nasal nerve located?
The external nasal nerve is located on the lateral aspect of the nose, in the region known as the alar groove. It is situated just above the nostril and below the infratrochlear nerve.
Function
The external nasal nerve serves a sensory function, providing sensation to the skin of the lateral aspect of the nose. This includes the alar cartilage and the alar groove. Sensation in this area is important for the sense of touch and for detecting changes in temperature and humidity.
Clinical significance
Dysfunction of the external nasal nerve can result in numbness or altered sensation in the skin of the lateral aspect of the nose. This may be caused by trauma or inflammation of the nerve. In some cases, surgical procedures involving the nose or orbital region may inadvertently damage the external nasal nerve, leading to sensory deficits. In addition, the external nasal nerve may be affected by certain medical conditions, such as diabetes mellitus, which can lead to neuropathy and sensory changes in the affected areas.
