What are the main functions of the trigeminal nerve (CN V)?

The trigeminal nerve is a mixed nerve with two key functions: sensory and motor. It provides general sensation (like pain, touch, and temperature) to the face, head, and oral/nasal cavities. Its motor component controls muscles of mastication and other muscles derived from the first pharyngeal arch.

What are the three divisions of the trigeminal nerve, and what do they innervate?

The trigeminal nerve splits into three divisions: Ophthalmic (V1) is purely sensory and supplies the upper face, including the scalp, eyelids, and cornea. Maxillary (V2) is purely sensory and innervates the midface, such as the maxilla, upper teeth, and palate. Mandibular (V3) is mixed and provides sensation to the lower face and motor control to muscles of mastication.

Why is the trigeminal nerve considered unique among cranial nerves?

The trigeminal nerve is unique because it is the largest cranial nerve, its sensory ganglion (trigeminal or gasserian) is the largest in the body and located within the cranial cavity, and it includes a proprioceptive component with unipolar sensory neurons in the mesencephalic nucleus, which is rare in the CNS.

What is trigeminal neuralgia, and what triggers it?

Trigeminal neuralgia (also called tic douloureux) is a condition characterized by sudden, severe facial pain, often affecting the maxillary and mandibular divisions. Common triggers include chewing, touching the face, or exposure to wind.

How does the trigeminal nerve's motor component function?

The motor component of the trigeminal nerve originates from the motor nucleus in the pons. It supplies muscles of mastication (like the masseter and temporalis), as well as other muscles such as the mylohyoid, anterior belly of the digastric, tensor tympani, and tensor palati.

Where is the trigeminal ganglion located, and what is its clinical significance?

The trigeminal (gasserian) ganglion is located within Meckel’s cave, a CSF-filled space on the petrous temporal bone. Clinically, it can be surgically accessed for procedures like trigeminal rhizotomy to treat refractory trigeminal neuralgia.

Trigeminal Nerve (CN V) – V1, V2, V3 & Mastication