Space
Cisterna magna
Large CSF cistern behind the lower brainstem
High-yield
The median aperture of Magendie links the fourth ventricle to this cerebellomedullary CSF space.
Overview
The cisterna magna occupies the interval between the inferior cerebellum and posterior medulla near the foramen magnum. It receives CSF from the fourth ventricle’s median aperture and communicates with surrounding cranial and spinal subarachnoid spaces.
Reference facts
- Boundaries
- Inferior cerebellum above/posteriorly, dorsal medulla and lower fourth-ventricular roof anteriorly, with the posterior foramen-magnum region below
- Contents
- CSF and PICA-related vessels. Vertebral arteries and lower cranial nerves relate to lateral cerebellomedullary compartments, which some descriptions include within a broader cisterna magna.
- Communications
- Median aperture to the fourth ventricle; continuity with neighboring posterior-fossa cisterns and spinal subarachnoid space
Clinical correlation
Downward tonsillar displacement can crowd the cistern and disturb CSF flow. A narrowed or effaced cistern is interpreted together with the surrounding brainstem, cerebellum and other imaging findings.
Frequently asked questions
What are the boundaries of the cisterna magna?
Inferior cerebellum above/posteriorly, dorsal medulla and lower fourth-ventricular roof anteriorly, with the posterior foramen-magnum region below.
What does the cisterna magna contain?
CSF and PICA-related vessels. Vertebral arteries and lower cranial nerves relate to lateral cerebellomedullary compartments, which some descriptions include within a broader cisterna magna.
What does the cisterna magna communicate with?
Median aperture to the fourth ventricle; continuity with neighboring posterior-fossa cisterns and spinal subarachnoid space.