CSF, Ventricles & Brain Anatomy
Cisterna magna
The cisterna magna is a large cerebrospinal fluid space behind the brainstem and below the cerebellum.
In short: Cisterna magna
- It is one of the largest CSF cisterns.
- It receives CSF exiting the fourth ventricle.
- It can be enlarged in some conditions (such as Dandy-Walker variants).
- It is a landmark on imaging.
What it is
The cisterna magna is a large pool of CSF located behind the brainstem and below the cerebellum, at the back of the head. It is one of the largest of the basal cisterns.
Understanding Cisterna magna
CSF exiting the fourth ventricle through the foramen of Magendie passes into the cisterna magna and then circulates around the brain and spinal cord. The cisterna magna can be enlarged in certain conditions, such as Dandy-Walker malformation and its variants, and its size and appearance are assessed on imaging. As a prominent landmark at the back of the brain, it is relevant when evaluating posterior fossa conditions associated with hydrocephalus.
Why it matters
Understanding the cisterna magna helps families recognize a major CSF space at the back of the brain that receives fluid from the fourth ventricle and can be involved in posterior fossa conditions linked to hydrocephalus.
Common questions
Where is the cisterna magna?
Behind the brainstem and below the cerebellum.
What does it receive?
CSF exiting the fourth ventricle.
Can it be enlarged?
Yes — in conditions such as Dandy-Walker variants.
Bottom line
The cisterna magna is a large CSF space behind the brainstem that receives fluid from the fourth ventricle.
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