cisterna magna

{{Short description|Space in the brain}}

{{Infobox Brain

| Name = Cisterna magna

| Latin = cisterna magna,
cisterna cerebellomedullaris posterior

| Image = Gray768.png

| Caption = Diagram showing the positions of the three principal cisterns in the brain. The cisterna magna is labelled as cisterna cerebellomedullaris at the lower right.

| Image2 =

| Caption2 =

| System = Ventricular

}}

The cisterna magna (posterior cerebellomedullary cistern,{{Cite web |title=Anatonomina |url=http://www.terminologia-anatomica.org/en/Terms/Occurence/5198 |access-date=2023-08-01 |website=www.terminologia-anatomica.org}} or cerebellomedullary cistern{{Cite book |last=Sinnatamby |first=Chummy S. |title=Last's Anatomy |publisher= Elsevier Australia|year=2011 |isbn=978-0-7295-3752-0 |edition=12th |pages=440}}{{Cite book |last=Standring |first=Susan |url=https://www.worldcat.org/oclc/1201341621 |title=Gray's Anatomy: The Anatomical Basis of Clinical Practice |year=2020 |isbn=978-0-7020-7707-4 |edition=42th |location=New York |pages=413 |oclc=1201341621}}) is the largest of the subarachnoid cisterns. It occupies the space created by the angle between the caudal/inferior surface of the cerebellum, and the dorsal/posterior surface of the medulla oblongata (it is created by the arachnoidea that bridges this angle). The fourth ventricle communicates with the cistern via the unpaired midline median aperture. It is continuous inferiorly with the subarachnoid space of the spinal canal.

The cisterna magna contains the two vertebral arteries, the origins of the two posterior inferior cerebellar arteries, the glossopharyngeal nerve (CN IX), vagus nerve (CN X), accessory nerve (CN XI), hypoglossal nerve (XII), and choroid plexus. The vertebral artery and posterior inferior cerebellar artery of either side pass traverse either lateral portion of the cistern.