Fourth ventricle

Encyclopedia : F : FO : FOU : Fourth ventricle

Coronal section of the pons, at its upper part. (Fourth ventricle visible near top.) |- style="text-align: center;" class="hiddenStructure" | colspan="2" |
|- style="text-align: center; line-height: 1;" class="hiddenStructure" | colspan="2" |Transverse section of medulla oblongata below the middle of the olive. (Fourth ventricle visible near top.) |- class="hiddenStructure" |Latin |colspan="2"|ventriculus quartus |- class="hiddenStructure" | |colspan="2"|[subject #187 ] |- class="hiddenStructure" |Part of |colspan="2"| |- class="hiddenStructure" |Components |colspan="2"| |- class="hiddenStructure" |Artery |colspan="2"| |- class="hiddenStructure" |Vein |colspan="2"| |- class="hiddenStructure" |Acronym(s) |colspan="2"| |- class="hiddenStructure" |NeuroNames |colspan="2"|[hier-617] |- class="hiddenStructure" |MeSH |colspan="2"|[A08.186.211.276.500] |- class="hiddenStructure" |Dorlands/Elsevier |colspan="2"|[/] |}
The fourth ventricle is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the ventricular system, consist of the left and right lateral ventricles, the third ventricle, and the fourth ventricle. 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 (see List of human anatomical parts named after people).
The fourth ventricle has a "roof" dorsally and a "floor" ventrally. The roof of the fourth ventricle is formed by the cerebellum, the floor by the rhomboid fossa, and the side "walls" formed by the cerebellar peduncles. Among the prominent features of the floor of the fourth ventricle are the:

facial colliculus: formed by the internal part of the facial nerve as it loops around the abducens nucleus in the lower pons;
sulcus limitans: which represents the border between the alar plate and the basal plate of the developing neural tube;
obex: represents the caudal tip of the fourth ventricle; the obex is also a marker for the level of the foramen magnum of the skull and therefore is a marker for the imaginary dividing line between the medulla and spinal cord.
External links
[Picture at University of Arkansas]
[High resolution neuroanatomical images of the fourth ventricle]
Brain: Fourth ventricle

Rhombencephalon (hindbrain)

MYELENCEPHALON/MEDULLA: arcuate nucleus of medulla, solitary nucleus, hypoglossal nucleus, nucleus ambiguus, olivary body, cuneate nucleus, accessory cuneate nucleus, gracile nucleus, inferior salivatory nucleus, nucleus raphe obscurus, nucleus raphe magnus, nucleus raphe pallidus, area postrema
METENCEPHALON/CEREBELLUM: cerebellar vermis, flocculus, arbor vitae
METENCEPHALON/PONS: pontine tegmentum, superior salivary nucleus, trapezoid body, pontine nuclei (superior olivary nucleus, trigeminal nerve nuclei, abducens nucleus, facial motor nucleus, cochlear nuclei, vestibular nuclei), locus ceruleus, paramedian pontine reticular formation, nucleus centralis superior
FOURTH VENTRICLE: obex, median aperture

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