- Fourth ventricle
Name = PAGENAME
Latin = ventriculus quartus
GraySubject = 187
GrayPage = 797
Caption = Scheme showing relations of the ventricles to the surface of the brain. (Fourth ventricle labeled at bottom center.)
Caption2 = Drawing of a cast of the ventricular cavities, viewed from above. (Fourth ventricle visible at bottom center.)
BrainInfoType = hier
BrainInfoNumber = 617
MeshName = Fourth+Ventricle
MeshNumber = A08.186.211.276.500
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
ponsor in the upper part of the medulla. CSF entering the fourth ventricle through the cerebral aqueduct can exit to the subarachnoid spaceof the spinal cordthrough 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).
Roof and floor
The fourth ventricle has a "roof" dorsally and a "floor" ventrally. The roof of the fourth ventricle is formed by the
cerebellum(superior and inferior medullary velums), 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 nerveas it loops around the abducens nucleusin the lower pons;
sulcus limitans: which represents the border between the alar plateand the basal plateof 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 magnumof the skulland therefore is a marker for the imaginary dividing line between the medulla and spinal cord.
* - "Fourth Ventricle, Sagittal Section, Medial View"
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