A trigeminal ganglion (or Gasserian ganglion, or semilunar ganglion, or Gasser's ganglion) is the sensory ganglion at the base of each of the two trigeminal nerves (CN V), occupying a cavity ( Meckel's cave) in the dura mater, covering the trigeminal impression near the apex of the petrous part of the

temporal bone The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. T ...

Structure

It is somewhat crescent-shaped, with its convexity directed forward: Medially, it is in relation with the

internal carotid artery The internal carotid artery (Latin: arteria carotis interna) is an artery in the neck which supplies the anterior circulation of the brain. In human anatomy, the internal and external carotids arise from the common carotid arteries, where these ...

and the posterior part of the

cavernous sinus The cavernous sinus within the human head is one of the dural venous sinuses creating a cavity called the lateral sellar compartment bordered by the temporal bone of the skull and the sphenoid bone, lateral to the sella turcica. Structure The cave ...

. The motor root runs in front of and medial to the sensory root, and passes beneath the ganglion; it leaves the skull through the

foramen ovale There are multiple structures in the human body with the name foramen ovale (plural: ''foramina ovalia''; Latin for "oval hole"): * Foramen ovale (heart), in the fetal heart, a shunt from the right atrium to left atrium * Foramen ovale (skull), at ...

, and, immediately below this foramen, joins the mandibular nerve. The

greater superficial petrosal nerve The greater petrosal nerve (or greater superficial petrosal nerve) is a nerve in the skull that branches from the facial nerve; it forms part of a chain of nerves that innervate the lacrimal gland. The preganglionic parasympathetic axons of this ne ...

lies also underneath the ganglion. The ganglion receives, on its medial side, filaments from the carotid plexus of the sympathetic. It gives off minute branches to the

tentorium cerebelli The cerebellar tentorium or tentorium cerebelli ( Latin for "tent of the cerebellum") is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes. Structure The cerebellar tentorium is an arc ...

, and to the dura mater in the middle fossa of the cranium. From its convex border, which is directed forward and lateralward, three large nerves proceed, viz., the ophthalmic (V₁), maxillary (V₂), and

mandibular In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

(V₃). The ophthalmic and maxillary consist exclusively of sensory fibers; the mandibular is joined outside the cranium by the motor root.

Clinical significance

After recovery from a primary

herpes Herpes simplex is a viral infection caused by the herpes simplex virus. Infections are categorized based on the part of the body infected. Oral herpes involves the face or mouth. It may result in small blisters in groups often called cold ...

infection, the virus is not cleared from the body, but rather lies dormant in a non-replicating state within the trigeminal ganglion. Herpes Labialis may follow from primary herpes infection/herpetic gingivostomatitis The trigeminal ganglion is damaged, by infection or surgery, in

Trigeminal trophic syndrome Trigeminal trophic syndrome is a rare disease caused by the interruption of peripheral or central sensory pathways of the trigeminal nerve. A slowly enlarging, uninflammed ulcer can occur in the area that has had trigeminal nerve damage; including ...

. Trigeminal trophic syndrome causes paresthesias and anesthesia, which may lead to erosions of the nasal ala. The thermocoagulation or injection of glycerol into the trigeminal ganglion has been used in the treatment of trigeminal neuralgia.

Other animals

Rodents

In rodents, the trigeminal ganglion is important as it is the first part of the pathway from the whiskers to the brain. Cell bodies of the whisker

primary afferents Afferent nerve fibers are the axons (nerve fibers) carried by a sensory nerve that relay sensory information from sensory receptors to regions of the brain. Afferent projections ''arrive'' at a particular brain region. Efferent nerve fibers ar ...

are found here. These afferents are mechanoreceptor cells that fire in response to whisker deflection. There are around 26,000–43,000 cell bodies in rodent Trigeminal ganglion. It is possible that there are two distinct (or perhaps continuous) populations of cells having slowly and rapidly adapting responses to stimuli. It is found at the base of the skull and projects to trigeminal

brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...

areas including principalis, spinal trigeminal nucleus, interpolaris, and caudalis.

Additional images

File:Gray193.png, Base of the skull. Upper surface. File:Gray777.png, Nerves of the orbit, and the ciliary ganglion. Side view. File:Gray783.png, The otic ganglion and its branches. File:Slide7nnn.JPG, Trigeminal ganglion File:Slide2ROM.JPG, Trigeminal ganglion. Deep dissection. Superior view.

References

External links

Diagram
at University of Manitoba
Diagram (as "Gasserian Ganglion")
at frca.co.uk * * * () {{Authority control Sensory ganglia Cranial nerves