The Trigeminal Nerve: Anatomy and Pathology (2023)

Section snippets


To review the basic anatomy, the magnetic resonance imaging (MRI) imaging technique, and the most common disorders involving trigeminal nerve (V).


The trigeminal nerve is the largest cranial nerve, composed of sensory and motor roots, to the muscles of face and mastication.5,7

The brainstem contains the motor and sensory nuclei of the trigeminal nerve, with the sensory divided in three: principal sensory nucleus, spinal nucleus and mesencephalic nucleus.1,2,7

The motor nucleus is on the lateral surface of the pontine tegmentum, medial and anterior to the major sensory nucleus.1,2

The principal sensory nucleus, or pontine nucleus, is located

Imaging Technique

Brainstem anatomy is better depicted with T2-weighted images. Although 1,5T or 3T MRI scans do not identify the nerve nucleus, their location can be deduced when the surrounding myelinated structures are recognized.

Heavily T2-weighted 3D-sequences are used to study the cisternal segment of the nerve and the Meckel cave, which are surrounded by cerebrospinal fluid (CSF). The trigeminal nerve is large and has a postero-anterior course. Therefore, it is easy to recognize it on most MRI planes.8

Congenital Anomalies

Congenital anomalies related to the trigeminal nerve are rare, with hypoplasia and aplasia the most common malformations reported. Most cases reported in the literature are unilateral and patients present with hypoesteshia or anaesthesia in the V1 territory, leading to corneal lesions, such as erosions or ulcerations.11, 12, 13

Oculo-auriculo-vertebral dysplasia or Goldenhar syndrome has been described with trigeminal nerve hypoplasia,12,14 but no clear genetic mutations or associations are

Trigeminal Neuralgia

Intracranial pain sensitive structures, responsible for pain sensitive stimuli, include dura and pia mater and its vessels and the cerebral blood vessels.17

The trigeminovascular system consists of the trigeminal neurons innervating the cerebral arteries, the pial and dural blood vessels, and venous sinuses, which activation is thought to be involved in migraine or pain, and most sensory fibers from the intracranial and the extracranial tissues originate in the gasserian ganglion.17


(Video) Trigeminal nerve (Introduction)

Neurovascular Compression Syndrome

Neurovascular compression syndrome (NVCS) is defined as direct contact with mechanical irritation of cranial nerves by blood vessels. The most NVCS are trigeminal neuralgia, hemifacial spasm and vestibulocochlear neuralgia.19

The pathophysiology is considered to be compression of the proximal centrally myelinated portion of the nerve, close to the root entry zone in the pons, by an adjacent vessel.18, 19, 20, 21 However, distal compression can be related to trigeminal neuralgia.

Although the

Secondary Trigeminal Neuralgia

Multiple sclerosis and benign tumors in the cerebellopontine angle are the most common causes of secondary trigeminal neuralgia.18

Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease leading to demyelination and axonal degeneration in the CNS. Neuropathic pain is a common symptom in patients with MS.24 The risk of trigeminal neuralgia is highly increased among patients with MS, with an estimated prevalence of 2 to 5% of the patients developing trigeminal neuralgia, and probably

Other Vascular Lesions

Brainstem or cisternal arteriovenous malformations (AVM), aneurysms, dural arteriovenous fistulas (dAVF) and vascular variants (27) are rare causes of trigeminal neuralgia.2,27,28 Patients with AVM presenting with trigeminal neuralgia, often have pain in the same side of the AVM, usually resulting from direct impingement or compression of the nerve by the malformation or compression/dislocation of the nerve by an arterialized draining vein.28

Brainstem infarcts rarely manifest with isolated


Epidermoid cysts represent approximately 1% of all primary intracranial tumors, are usually located in the cerebellopontine angle (40%), being the third most common tumor in this region. Still, other sites such as the fourth ventricle and suprasellar region are reported.35,36

Trigeminal neuralgia in patients with epidermoid cysts is typical, but the reported incidence of epidermoid cysts in patients with trigeminal neuralgia is rare (0.2% to 5.5%) and can be due to direct cranial nerve


The trigeminal nerves are the fifth cranial nerves and are sensory-motor nerves that provide the innervation to the face with its three roots. The trigeminal nerve can be affected by a myriad of diseases, and MRI plays an important role in its evaluation.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all individual participants included in the study.

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What is the trigeminal nerve in Statpearls? ›

The trigeminal nerve is the fifth cranial nerve (CN V) and the largest of the cranial nerves. Its primary function is to provide sensory innervation to the face and is divided into three main branches. The different branches are the ophthalmic (V1), maxillary (V2), and mandibular (V3) nerves.

What are the pathologic conditions affecting trigeminal nerve? ›

The trigeminal nuclei may be affected by gliomas, lymphomas, and hematogenous metastases to the brainstem. Brainstem gliomas account for 10% to 20% of all childhood brain tumors. The incidence in adults is lower than that in children younger than 16.

What causes trigeminal nerve pain? ›

Causes of Trigeminal Neuralgia

Trigeminal neuralgia usually occurs spontaneously, but is sometimes associated with facial trauma or dental procedures. The condition may be caused by a blood vessel pressing against the trigeminal nerve, also known as vascular compression.

How long does it take for the trigeminal nerve to heal? ›

During surgery, nerve scar tissue is traced back to where it's still healthy in the soft tissue and the nerve repaired. This provides a path for the nerve to regrow, which takes about six to nine months.

What is the most common cause of trigeminal neuralgia? ›

Classical trigeminal neuralgia is caused by pressure on the trigeminal nerve close to where it enters the brain stem. The brain stem is the lowest part of the brain that merges with the spinal cord. In most cases the pressure is caused by an artery or vein squashing (compressing) the trigeminal nerve.

What is the most affected nerve in trigeminal neuralgia? ›

Trigeminal neuralgia (TN), also known as tic douloureux, is a type of chronic pain disorder that involves sudden, severe facial pain. It affects the trigeminal nerve, or fifth cranial nerve, which provides feeling and nerve signaling to many parts of the head and face.


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