====== Fourth ventricle ======
{{ http://upload.wikimedia.org/wikipedia/commons/3/36/Gray768.png?400}}

Knowledge of anatomy of the IV [[ventricle]] is basic to surgical approach of any kind of lesion in its compartment as well as for those located in its neighborhood.

It is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the [[ventricular system]].

The fourth ventricle extends from the [[cerebral aqueduct]] ([[aqueduct of Sylvius]]) to the [[obex]], and is filled with cerebrospinal fluid (CSF).

The fourth ventricle has a characteristic diamond shape in cross-sections of the human brain. It is located within the [[pons]] or in the upper part of the [[medulla]]. CSF entering the fourth ventricle through the cerebral aqueduct can exit to the subarachnoid space of the spinal cord through two lateral foramina of Luschka (singular: [[foramen of Luschka]]) and a single, midline [[foramen of Magendie]].

[[Cerebrospinal fluid]] (CSF) pathway studies have revealed that the CSF secreted from the [[choroid plexus]] of the [[ventricle]]s after egressing from the [[fourth ventricle]] reaches the basal [[suprasellar cistern]] and ultimately the [[sylvian cistern]]s.
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It has an anteroinferior wall or floor, consisting of the pons and bulb, and a posterior superior wall or roof, which ends in a point at the level of the fastigium or posterior recess, consisting of the cerebellum and the posterior choroid tissue
((Fontana H, Belziti H, Requejo F, Recchia M. Buratti S. Los recesos del IV ventrículo.
Rev Argent Neuroc. 2006; 20:101-13.))

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The IV ventricle in a midline sagittal cut shows a tent-shaped cavity with its roofs pointing posteriorly and the [[floor]] formed by the [[pons]] and the [[medulla]]. The superior roof is formed by the [[superior cerebellar peduncle]]s laterally and the [[superior medullary velum]] on the midline. The inferior roof is formed by the [[tela chorioidea]], the velum medullary inferior, and the [[nodule]]. The floor of the IV ventricle has a rhomboid shape. The rostral two thirds are related to the pons, and the caudal one third is posterior to the medulla. The median sulcus divides the floor in symmetrical halves. The sulcus limitans runs laterally to the median sulcus, and the area between the two sulci is called the median eminence. The median eminence contains rounded prominence related to the cranial nucleus of facial, hypoglossal, and vagal nerves. The lateral recesses are extensions of the IV ventricle that opens into the cerebellopontine cistern. The cerebellomedullary fissure is a space between the cerebellum and the medulla and can be used as a surgical corridor to the IV ventricle
((Mussi AC, Matushita H, Andrade FG, Rhoton AL. Surgical approaches to IV
ventricle--anatomical study. Childs Nerv Syst. 2015 Oct;31(10):1807-14. doi:
10.1007/s00381-015-2809-0. Epub 2015 Sep 9. PubMed PMID: 26351232.)).

{{::fourthventricle.jpg|}}

===== Fourth ventricle floor =====
[[Fourth ventricle floor]]


===== Pathology =====

see [[Trapped fourth ventricle]].

[[Fourth ventricle tumor]]

[[Fourth ventricle hematoma]]

[[Fourth ventricle arachnoid cyst]]

===== Approaches =====

see [[Fourth ventricle approaches]].