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Lateral cerebellomedullary cistern

The lateral cerebellomedullary cistern is a paired, CSF-filled subarachnoid space situated at the inferolateral aspect of the medulla oblongata, between the cerebellum and the medulla, and lateral to the fourth ventricle. It serves as a conduit for cranial nerves and blood vessels traversing the posterior cranial fossa. This cistern is continuous with the larger cisterna magna (cerebellomedullary cistern proper) medially, and communicates inferiorly with the spinal subarachnoid space. It is clinically significant as it can harbor various pathologies, such as vascular malformations, cysts, or tumors, and is a key landmark in neuroimaging.

Synonyms

  • Lateral cerebellomedullary cistern

  • Lateral cerebellomedullary recess

  • Lateral cerebellomedullary subarachnoid cistern

  • Lateral part of the cisterna magna

Function

  • Serves as a reservoir and conduit for cerebrospinal fluid (CSF) circulation within the posterior cranial fossa.

  • Provides a protective cushion for neurovascular structures, including cranial nerves IX (glossopharyngeal), X (vagus), XI (accessory), and portions of XII (hypoglossal), as well as the posterior inferior cerebellar artery (PICA).

  • Acts as an anatomical corridor for neurosurgical access to posterior fossa structures.

MRI Appearance

  • T1-weighted Images:

    • Appears hypointense (dark), similar to CSF elsewhere, as CSF has low signal intensity on T1.

    • Neurovascular structures within the cistern may be visualized as linear or dot-like low-signal structures within the fluid.

  • T2-weighted Images:

    • Appears hyperintense (bright), as CSF has high signal intensity on T2.

    • Cranial nerves and vessels may appear as signal voids (dark lines or dots) within the bright background.

  • FLAIR (Fluid-Attenuated Inversion Recovery):

    • Normally, the cistern appears hypointense (dark), as CSF signal is suppressed.

    • Any abnormal content (e.g., blood, pus, tumor) may appear as increased signal (bright) within the otherwise dark cistern.

CT Appearance

  • Appears as a well-defined, hypodense (dark) area in the posterior fossa, lateral to the medulla and cerebellum, corresponding to the CSF density.

  • Blood, masses, or calcifications within the cistern can be identified as areas of increased density (hyperdense) or structural distortion.

  • Bony margins of the posterior fossa are seen surrounding the cistern, which remains radiolucent (dark) due to CSF content.

MRI images

Lateral cerebellomedullary cistern mri 3t coronal image

MRI images

Lateral cerebellomedullary cistern mri 3t sagittal image

CT image

Lateral cerebellomedullary cistern CT coronal anatomy image -img-00001-00001