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Retrocerebellar Cistern

cisterna posterior (magna)

The retrocerebellar cistern (posterior cisterna magna or cisterna cerebellomedullaris posterior) is the large subarachnoid space between the posterior surface of the cerebellum, the posterior medulla, and the posterior atlanto-occipital membrane. It is the largest subarachnoid cistern, receiving CSF from the fourth ventricle through the foramen of Magendie. It communicates with the spinal subarachnoid space inferiorly and with the lateral cerebellomedullary cisterns through the foramina of Luschka.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The retrocerebellar cistern is accessed by cisternal puncture (posterior suboccipital puncture) for CSF sampling when lumbar puncture is contraindicated (mass lesion, coagulopathy). Mega-cisterna magna is an isolated enlargement of this cistern without cerebellar or vermian pathology — a normal variant requiring no treatment. Dandy-Walker malformation involves a cystic fourth ventricle connecting with an enlarged posterior cisterna magna and vermian hypoplasia. The cistern is the entry point for the posterior fossa craniotomy in cerebellopontine angle tumour surgery.

Pathology

Common Injuries & Conditions

Dandy-Walker Complex Involving Retrocerebellar Cistern

Dandy-Walker malformation produces fourth ventricle cystic dilation that communicates with a greatly enlarged retrocerebellar cistern, displacing the cerebellar vermis superiorly and laterally with variable cerebellar hemisphere hypoplasia; MRI clearly delineates the posterior fossa cyst and associated hydrocephalus requiring ventriculoperitoneal shunting.