Premedullary cistern

The premedullary cistern is located between the medulla and the clivus. His upper boundary is the pontomedullary jonction and his lower boundary is the foramen magnum.

Relationships:

• Superiorly: prepontine cistern

• Inferiorly: spinal subarachnoid space

• Laterally: paired lateral cerebellomedullary cisterns

Contents:

• Union of vertebral arteries (vertebrobasilar confluence)

• Posterior inferior cerebellar artery (PICA)

• Anterior spinal artery

• Hypoglossal nerve (CN XII)

Just above the foramen magnum, the cranial cisterna are building a ring around the inferior portion of the brainstem (the medulla). this cisternal space corresponds anteriorly to the premedullaris cistern, laterally to the lateral cerebellomedullary cistern, and posteriorly to the posterior cerebellomedullary cistern (cisterna magna).