The fifth cranial nerve (CNV) is also named the trigeminal nerve. It provides both sensory and motor innervation to each side of the face. The trigeminal nerve is divided into three pairs (hence the name trigeminal - tri = three, gemini = twins) that serve the upper, middle, and lower portions of the face.
All cranial nerves (all nerves for that matter) have a nucleus (cell body) and axon (that carries nerve impulses away from the nucleus to other structures). The nucleus of CNV is located in the pons of the brainstem.
The trigeminal nerve is divided into three different branches: -Ophthalmic (V1) - innervates the upper third of the face as well as the eye and tip of the nose -Maxillary (V2) - innervates the nasal cavity, sinuses, some teeth, upper portion of the mouth, and the middle third of the face from the mouth to the forehead -Mandibular (V3) - innervates the mucous membranes of the mouth, part of the tongue, some teeth, and lower third of the face along the jawline
A quick review of the location and destination of CNIV: -Starts in the PONS -Has both motor and sensory components -Divides into three portions, ophthalmic (V1), maxillary (V2), and mandibular (V3)
Damage to the trochlear nerve can occur anywhere along its path. The three-branch division of the trigeminal nerve often causes specific areas of the face to be affected if the trigeminal nerve is damaged.
The eye and part of the face can become painful and develop sores (ulcerations) on the cornea or skin due to activation of the herpes zoster virus - the same virus that causes the chickenpox early in life.
Damage to the trigeminal nerve can occur due to compression, trauma, or infection. The pain is often well-localized and can be quite painful.
Some headaches can be caused by abnormal activation of the trigeminal nerve. The result is often a severe, unilateral (single-side) pain anywhere along the affected branch of the trigeminal nerve.