Cisterna magna

Last revised by Assoc Prof Frank Gaillard on 26 Jul 2022

The cisterna magna (also known as the posterior cerebellomedullary cistern) is the largest of the CSF-filled subarachnoid cisterns.

The cisterna magna is located between the cerebellum and the dorsal surface of the medulla oblongata at and above the level of the foramen magnum. CSF produced in the ventricular system drains into the cisterna magna from the fourth ventricle via the median aperture (of Magendie) and the lateral apertures (of Luschka) 1,2.

Several vessels and nerves course through the lateral part of the cistern:

  • cisterna magna normally measures between 2-10 mm in the second and third trimesters 4
  • cisterna magna normally measures 3-8 mm in the midsagittal plane when measured from the posterior margin of the foramen magnum to the caudal margin of the inferior vermis 3

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Cases and figures

  • Figure 1: subarachnoid cistern
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  • Figure 2: cisterns and CSF flow
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  • Fig 3: cerebellomedullary cisterns
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