Median aperture explained

Median aperture
Latin:	apertura mediana ventriculi quarti

The median aperture (also known as the medial aperture and foramen of Magendie) is an opening of the fourth ventricle at the caudal portion of the roof of the fourth ventricle.^[1] It allows flow of cerebrospinal fluid (CSF) from the fourth ventricle into the cisterna magna.^{[2] [3]} The other two openings of the fourth ventricle are the lateral apertures - one on either side. Nonetheless, the median aperture accounts for most of the outflow of CSF out of the fourth ventricle. The median aperture varies in size.

Structure

Relations

The median foramen on axial images is posterior to the pons and anterior to the caudal cerebellum. It is surrounded by the obex and gracile tubercles of the medulla, tela choroidea of the fourth ventricle and its choroid plexus, which is attached to the cerebellar vermis.^{[4] [5]}

Eponym

The foramen of Magendie is named for François Magendie, who first described it. The term "foramen of Magendie" is commonly used, and this opening is frequently described and illustrated as a foramen in the inferior roof of the fourth ventricle. However, the opening is an aperture, rather than a foramen.

Notes and References

1. Book: Waxman, Stephen G. . Clinical Neuroanatomy . McGraw-Hill Medical . 2009 . 978-0-07-160399-7 . 26th . New York . 150.
2. Book: Johns, Paul . Clinical Neuroscience . Development of the brain . Elsevier . 2014 . 978-0-443-10321-6 . 10.1016/b978-0-443-10321-6.00002-3 . 19–26 . The choroid plexuses are highly vascular structures that project into each of the ventricles and continuously produce cerebrospinal fluid by active secretion from the blood. CSF escapes from the fourth ventricle (to the subarachnoid space) via three openings: the single median aperture and the two lateral apertures. It is ultimately reabsorbed into the venous system via the arachnoid granulations which run along the superior aspect of the cerebral hemispheres ... correspond to the arachnoid villi, finger-like projections into a large venous channel called the superior sagittal sinus..
3. Book: Singhal . Vasudha . Prabhakar . Hemanshu . Complications in Neuroanesthesia . Hydrocephalus . Elsevier . 2016 . 978-0-12-804075-1 . 10.1016/b978-0-12-804075-1.00003-1 . 21–27 . CSF is produced by the choroid plexuses of the lateral, third, and fourth ventricle. The production of CSF is not pressure regulated, and it continues to be produced even if the reabsorption mechanisms are obstructed. The circulation of CSF is as follows: Lateral ventricle → interventricular foramen of Monroe → third ventricle → aqueduct of sylvius → fourth ventricle → foramen of Magendie (median aperture)/foramen of Luschka (lateral aperture) → subarachnoid space..
4. Ciolkowski M. . Sharifi M. . Tarka S. . Ciszek B. . Median aperture of the fourth ventricle revisited. . Folia Morphol.. 2011 . 70 . 2 . 84–90. 21630228.
5. Spierer . Ronen . 2023 . The debated neuroanatomy of the fourth ventricle . Journal of Anatomy . 243 . 4 . 555–563 . 10.1111/joa.13885 . 1469-7580 . 37170923. 10485575 .