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Interventricular foramina

Brain: Interventricular foramina
Mesal aspect of a brain sectioned in the median sagittal plane. ("Foramen of Monro" label at top.)
Coronal section of lateral and third ventricles. (Foramen not displayed, but relationship between ventricles can be observed.)
Latin foramen interventriculare
Gray's subject #189 840
Part of Ventricular system
NeuroNames hier-430
MeSH Foramen+of+Monro

In the brain, the interventricular foramina (or foramina of Monro) are channels that connect the paired lateral ventricles with the third ventricle at the midline of the brain. As channels, they allow cerebrospinal fluid (CSF) produced in the lateral ventricles to reach the third ventricle and then the rest of the brain's ventricular system. They also contain choroid plexus, a specialized CSF-producing structure, that is continuous with that of the lateral and third ventricles.



The crescent-shaped interventricular foramina are located on the medial and inferior aspect of the lateral ventricles. Each foramen is bounded by the fornix and thalamus. The lumens of the foramina have a diameter of several millimeters.

Clinical relevance

Inflammation, tumor, or other conditions that may occlude the foramina may lead to internal hydrocephalus.


The foramina were named after the Scottish physician Alexander Monro, who first described the structures in his 1783 publication, Observations on the Structure and Functions of the Nervous System. They had previously been identified by the 17th century anatomist Raymond Vieussens.

Additional images


  • Kiernan, John A. (2005). Barr's The Human Nervous System: An Anatomical Viewpoint. Lippincott Williams & Wilkins, 220. ISBN 0-7817-5154-3. 
  • History of Neuroscience, from the University of Washington
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Interventricular_foramina". A list of authors is available in Wikipedia.
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