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Trigeminal ganglion

The trigeminal ganglion—also known as the Gasserian ganglion or semilunar ganglion—is a large sensory ganglion of the trigeminal nerve (cranial nerve V). Located within Meckel's cave in the middle cranial fossa, it is crucial for facial sensation, relaying sensory input from the face, scalp, sinuses, oral cavity, and meninges to the brainstem. It serves as the point where the trigeminal nerve divides into its three major branches: the ophthalmic (V1), maxillary (V2), and mandibular (V3) nerves.

Synonyms

  • Gasserian ganglion

  • Semilunar ganglion

  • Trigeminal (sensory) ganglion

Function

  • Serves as the principal sensory ganglion for the trigeminal nerve (cranial nerve V).

  • Houses the cell bodies of sensory neurons that transmit pain, touch, pressure, and temperature sensations from the face and head.

  • Gives rise to the three main branches of the trigeminal nerve:

    • Ophthalmic nerve (V1)

    • Maxillary nerve (V2)

    • Mandibular nerve (V3)

  • Essential in the perception of facial sensation and involved in various reflex pathways.

MRI Appearance

  • 3D T2-Weighted MRI:

    • Trigeminal ganglion appears as a small, ovoid, well-circumscribed, hypointense (dark) to isointense structure relative to brain parenchyma.

    • Surrounded by hyperintense (bright) cerebrospinal fluid (CSF) within Meckel's cave.

    • The three trigeminal nerve branches may be visible extending anteriorly.

    • Meckel’s cave itself is seen as a CSF-filled cavity at the petrous apex of the temporal bone.

  • T1-Weighted MRI:

    • Trigeminal ganglion demonstrates isointense to slightly hypointense signal compared to brain parenchyma.

    • Less contrast than on T2-weighted images.

    • Enhancement may be seen if contrast is administered, especially in cases of pathology (e.g., tumors or inflammation).

    • Bounded by low signal CSF in Meckel’s cave, providing anatomical delineation.

CT Appearance

  • Appears as a soft tissue density within the Meckel’s cave at the petrous apex.

  • Not directly visualized unless enlarged or displaced by pathology.

  • Bony landmarks such as the foramen ovale and foramen rotundum can be identified adjacent to the ganglion.

  • CT cisternography may help outline Meckel's cave and associated ganglion if needed for specific indications.

MRI image

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Trigeminal ganglion MRI axial anatomy image -img-00001-00001