The fourth ventricle is one of the four connected fluid-filled cavities within the

human brain The human brain is the central organ (anatomy), organ of the nervous system, and with the spinal cord, comprises the central nervous system. It consists of the cerebrum, the brainstem and the cerebellum. The brain controls most of the activi ...

. These cavities, known collectively as the

ventricular system In neuroanatomy, the ventricular system is a set of four interconnected cavities known as cerebral ventricles in the brain. Within each ventricle is a region of choroid plexus which produces the circulating cerebrospinal fluid (CSF). The ventric ...

, consist of the left and right

lateral ventricles The lateral ventricles are the two largest ventricles of the brain and contain cerebrospinal fluid. Each cerebral hemisphere contains a lateral ventricle, known as the left or right lateral ventricle, respectively. Each lateral ventricle resemb ...

, the

third ventricle The third ventricle is one of the four connected cerebral ventricles of the ventricular system within the mammalian brain. It is a slit-like cavity formed in the diencephalon between the two thalami, in the midline between the right and lef ...

, and the fourth ventricle. The fourth ventricle extends from the

cerebral aqueduct The cerebral aqueduct (aqueduct of the midbrain, aqueduct of Sylvius, Sylvian aqueduct, mesencephalic duct) is a small, narrow tube connecting the third and fourth ventricles of the brain. The cerebral aqueduct is a midline structure that passe ...

(''aqueduct of Sylvius'') to the

obex The obex () is the point in the human brain at which the fourth ventricle narrows to become the central canal of the spinal cord. Cerebrospinal fluid can flow from the fourth ventricle into the obex. In anatomical studies, the obex has been fo ...

, and is filled with

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless Extracellular fluid#Transcellular fluid, transcellular body fluid found within the meninges, meningeal tissue that surrounds the vertebrate brain and spinal cord, and in the ventricular system, ven ...

(CSF). The fourth ventricle has a characteristic diamond shape in cross-sections of the human brain. It is located within the

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other mammals, lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of ...

or in the upper part of the

medulla oblongata The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involun ...

. CSF entering the fourth ventricle through the cerebral aqueduct can exit to the subarachnoid space of the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

through two lateral apertures and a single, midline

median aperture The median aperture (median aperture of fourth ventricle or foramen of Magendie) is an opening at the caudal portion of the roof of the fourth ventricle. It allows the flow of cerebrospinal fluid (CSF) from the fourth ventricle into the cisterna ...

Boundaries

Fourth Ventricle in the Human Cerebellum

The fourth ventricle has a

roof A roof (: roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of tempera ...

at its ''upper'' (posterior) surface and a floor at its ''lower'' (anterior) surface, and side walls formed by the cerebellar peduncles (nerve bundles joining the structure on the posterior side of the ventricle to the structures on the anterior side). The caudal tip of the fourth ventricle - where it becomes the

central canal The central canal (also known as spinal foramen or ependymal canal) is the cerebrospinal fluid-filled space that runs through the spinal cord. The central canal lies below and is connected to the ventricular system of the brain, from which it r ...

- is known as the

; the obex is also a marker for the level of the

foramen magnum The foramen magnum () is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes thro ...

of the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

and therefore is a marker for the imaginary dividing line between the

medulla Medulla (Latin for "marrow") or medullary may refer to: Science * Medulla oblongata, a part of the brain stem * Renal medulla, a part of the kidney * Adrenal medulla, a part of the adrenal gland * Medulla of ovary, a stroma in the center of the ...

and

. The superior portion of the ''roof'' (i.e. of the posterior edge) is formed, in the midline, by a thin lamina called the

superior medullary velum The superior medullary velum (anterior medullary velum) is a thin, transparent lamina of white matter which - together with the inferior medullary velum - forms the roof of the fourth ventricle. It extends between the two superior cerebellar ped ...

, and laterally by the cerebellar peduncles. The inferior portion of the ''roof'' is formed superiorly by the inferior medullary veli and the vermis of the

Cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or eve ...

(covered with

choroid plexus The choroid plexus, or plica choroidea, is a plexus of cells that arises from the tela choroidea in each of the ventricles of the brain. Regions of the choroid plexus produce and secrete most of the cerebrospinal fluid (CSF) of the central ...

), and inferiorly by the

tela Tela is a town, with a population of 39,920 (2023 calculation), and a municipality in Honduras on the northern Caribbean coast. It is located in the Atlántida department, department of Atlantida. History Colonial era Tela was founded by th ...

. The inferior portion of the ''roof'' is where CSF can escape the ventricle through three openings: Near each of the three corners of the inferior roof there is an opening into the

cisterna magna The cisterna magna (posterior cerebellomedullary cistern, or cerebellomedullary cistern) is the largest of the subarachnoid cisterns. It occupies the space created by the angle between the caudal/inferior surface of the cerebellum, and the dorsa ...

, the caudal opening being the '' foramen Magendie'', while the lateral openings are the ''

foramina of Luschka The lateral aperture, lateral aperture of fourth ventricle or foramen of Luschka (after anatomist Hubert von Luschka)Huber ...

''. Therefore, the fourth ventricle is the connector between the ventricular system (where CSF is produced) and the subarachnoid space (where CSF is absorbed). The ''roof'' rises (i.e. posteriorly) to a peak, known as the fastigium (Latin for "summit"); the

fastigial nucleus The fastigial nucleus (roof nucleus-1) is located in each cerebellar hemisphere. It is one of the four paired deep cerebellar nuclei of the cerebellum. It is made up of two sections: the rostral fastigial nucleus and the caudal fastigial nucle ...

lies immediately above the roof of the fourth ventricle, in the cerebellum. The ''floor'' (i.e. the anterior edge) of the fourth ventricle constitutes the

rhomboid fossa The rhomboid fossa is a rhombus-shaped depression that is the anterior part of the fourth ventricle. Its anterior wall, formed by the back of the pons and the medulla oblongata, constitutes the floor of the fourth ventricle. It is covered by a t ...

, and comprises a number of general features. A sulcus - the median sulcus - extends the length of the ventricle (from the

of the midbrain to the central canal of the spinal cord), dividing the floor into right and left halves. Each half is further divided by a further sulcus - the

sulcus limitans The sulcus limitans is a groove on either side of the midline in the rhomboid fossa. It separates the cranial nerve Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventiona ...

- along a line parallel to the median sulcus; within the floor, motor neurons are located medially of the sulcus limitans, while sensory neurons are located laterally. The elevation between the median sulcus and sulcus limitans (i.e. the region for motor neurons), is known as the ''

medial eminence In the human brain, the rhomboid fossa is divided into symmetrical halves by a median sulcus which reaches from the upper to the lower angles of the fossa and is deeper below than above. On either side of this sulcus is an elevation, the medial em ...

'', while the lateral region (i.e. that for the sensory neurons) is known as the ''vestibular area''. The sulcus limitans bifurcates at either end - the ''superior fovea'' cerebrally, and the ''inferior fovea'' caudally. The

is located behind the middle and superior portion of the ''floor''. In the superior region of the pons is the

locus coeruleus The locus coeruleus () (LC), also spelled locus caeruleus or locus ceruleus, is a nucleus in the pons of the brainstem involved with physiological responses to stress and panic. It is a part of the reticular activating system in the reticular ...

, which due to its concentration of

noradrenaline Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as a hormone, neurotransmitter and neuromodulator. The name "noradrenaline" (from ...

has a

sky blue Sky blue refers to a collection of shades comparable to that of a clear daytime sky. Typically it is a shade of cyan or light teal, though some iterations are closer to light Azure (color), azure or light blue. The term (as "sky blew") is atte ...

appearance, visible (in a colour closer to teal) through the floor of the ventricle, superiorly to the superior fovea. The internal part of the

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of ta ...

bulges into the ventricle, forming the

facial colliculus The facial colliculus is an elevated area located in the pontine tegmentum (dorsal pons), within the floor of the fourth ventricle (i.e. the rhomboid fossa). It is formed by fibres from the facial motor nucleus looping over the abducens nucleus. ...

, in the process of looping around the

abducens nucleus The abducens nucleus is the originating nucleus from which the abducens nerve (VI) emerges—a cranial nerve nucleus. This nucleus is located beneath the fourth ventricle in the Anatomical terms of location#Rostral, cranial, and caudal, caudal por ...

within the inferior region of the Pons. The

is located behind the inferior portion of the ''floor'' (and continues caudally of the ventricle). Medullary striae emerge via the median sulcus and run transversely across the floor to become part of the

inferior cerebellar peduncle The inferior cerebellar peduncle is formed by fibers of the restiform body that join with fibers from the much smaller juxtarestiform body. The inferior cerebellar peduncle is the smallest of the three cerebellar peduncles. The upper part of t ...

. The

hypoglossal nucleus The hypoglossal nucleus is a cranial nerve nucleus, found within the medulla. Being a motor nucleus, it is close to the midline. In the open medulla, it is visible as what is known as the '' hypoglossal trigone'', a raised area (medial to the v ...

bulges into the ''floor'', creating the

hypoglossal trigone In the upper part of the medulla oblongata, the hypoglossal nucleus approaches the rhomboid fossa The rhomboid fossa is a rhombus-shaped depression that is the anterior part of the fourth ventricle. Its anterior wall, formed by the back of the p ...

, located slightly superiorly to the inferior fovea, within the median eminence. The

dorsal nucleus of vagus nerve The dorsal nucleus of vagus nerve (or posterior nucleus of vagus nerve or dorsal vagal nucleus or nucleus dorsalis nervi vagi or nucleus posterior nervi vagi) is a cranial nerve nucleus of the vagus nerve (CN X) situated in the medulla oblongata ...

, within the medulla oblongata, comprises cells that are spindle shaped, also creating a bulge—the

vagal trigone The vagal trigone (ala cinerea) is a triangular eminence upon the rhomboid fossa produced by the underlying dorsal nucleus of vagus nerve. The vagal trigone is separated from the area postrema by a narrow strip of thickened ependyma The epend ...

—in the region of the ''floor'' which overlies them; this is the region inferior of the inferior fovea.

Development

The ventricular system including the fourth ventricle, develops from the

of the neural tube. Specifically, the fourth ventricle originates from the portion of the tube that is present in the developing

rhombencephalon The hindbrain, rhombencephalon (shaped like a rhombus) is a developmental categorization of portions of the central nervous system in vertebrates. It includes the medulla, pons, and cerebellum. Together they support vital bodily processes. Met ...

. During the first trimester of pregnancy the central canal expands into the lateral, third and fourth ventricles, connected by thinner channels.

Choroid plexus The choroid plexus, or plica choroidea, is a plexus of cells that arises from the tela choroidea in each of the ventricles of the brain. Regions of the choroid plexus produce and secrete most of the cerebrospinal fluid (CSF) of the central ...

es appear in the ventricles which produce

. If the flow of fluid is blocked ventricles may become enlarged and cause

hydrocephalus Hydrocephalus is a condition in which cerebrospinal fluid (CSF) builds up within the brain, which can cause pressure to increase in the skull. Symptoms may vary according to age. Headaches and double vision are common. Elderly adults with n ...

Clinical significance

The floor of the fourth ventricle is a common location of an

intracranial The cranial cavity, also known as intracranial space, is the space within the skull that accommodates the brain. The skull is also known as the cranium. The cranial cavity is formed by eight cranial bones known as the neurocranium that in human ...

ependymoma An ependymoma is a tumor that arises from the ependyma, a tissue of the central nervous system. Usually, in pediatric cases the location is intracranial, while in adults it is spinal. The common location of intracranial ependymomas is the floor ...

in children.

Additional images

File:Gray695.png, Transverse section of medulla oblongata below the middle of the olive. File:Gray708.svg, Scheme of

roof of fourth ventricle The roof of fourth ventricle is the dorsal surface of the fourth ventricle. It corresponds to the ventral surface of the cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of ...

. File:Gray709.png, Rhomboid fossa. File:Gray720.png, Median sagittal section of brain. File:Gray736.png, Drawing of a cast of the ventricular cavities, viewed from the side. File:Gray768.png, Diagram showing the positions of the three principal subarachnoid cisternæ. File:Slide6qq.JPG, Fourth ventricle

References

External links

* - "Fourth Ventricle, Sagittal Section, Medial View" * * {{Authority control Brainstem Ventricular system de:Hirnventrikel#Vierter Ventrikel