Cerebral ventricle

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Position of the brain ventricles in the 3D model.
Spout of the ventricular system,
side view from the right
Spout of the ventricular system
supervision; the face would be facing the upper edge of the picture
Blue: Lateral ventricle
Cyan: Foramen Monroi
Yellow: Third ventricle
Red: Aquaeductus mesencephali
Purple: Fourth ventricle
Green: Central canal (shortened)
Openings into the subarachnoid space (e.g. Foramina Luschkae , Foramen Magendii , ...) are not shown!

Cerebral ventricles are cavities in the brain filled with cerebrospinal fluid ( liquor cerebrospinalis ) . Together with the spinal canal ( canalis centralis medullaris ), they form the internal liquor space . The brain has a lateral ventricle in each cerebral hemisphere, a third ventricle in the diencephalon and the fourth ventricle in the rhombencephalon . These four cerebral ventricles are connected to each other as the ventricular system and to the central canal through holes ( foramina ) and lines like the aqueductus mesencephali .

The ventricles are lined with tissue called the ependyma . The brain water is from lying in the ventricles wire braids ( choroid plexus formed). In addition, in the median plane around the ventricular system, there are various unpaired, so-called circumventricular organs with specific ependymal formations as the ventricular wall.

Lateral ventricle

The two lateral ventricles or lateral ventricles are located in the cerebrum ; Their complex shape with anterior horn ( Cornu anterius / frontale ), middle part ( Pars centralis , Cella media ), posterior horn ( Cornu posterius / occipitale ), and lower horn ( Cornu inferius / temporale ) is caused by the evolutionary rotation of the cerebrum (see also: Brain Development in humans ). The lateral ventricles are each connected to the third ventricle via an interventricular foramen ( Monroi foramen ).

Although all four parts of the lateral ventricle flow smoothly into one another, they can be anatomically limited as follows: the bottom of the anterior horn is formed by the rostrum corporis callosi , the anterior wall by the genu corporis callosi, the side wall by the caput nuclei caudati , the inner wall by the septum pellucidum and the Roof of the Truncus corporis callosi. The bottom of the central part is formed by the stria terminalis , the lamina affixa plexus choroidus and the crus fornicis , the side wall by the corpus nuclei caudati, the inner wall of the crus fornicis and septum pellucidum and the roof of the trunk corporis callosi. The posterior horn is bordered at the bottom by the trigonum collaterale and the eminentia collateralis, inside by the calcar avis and laterally by the tapetum . The base of the lower horn is formed by the eminentia collateralis and alveus hippocampi , the inner wall by the fimbria hippocampi and the choroid plexus, and the side wall by the cauda nuclei caudati and the tapetum.

For the cornu posterius and the cornu inferius it applies that the sideways ( lateral ) wall also corresponds to the roof. The anterior horn and the posterior horn are free from the choroid plexus, since these structures are secondary protuberances which, in terms of development, arise only after the plexus has a fixed course.

When defined more precisely, the two lateral ventricles are also referred to as the first (left) and second (right) cerebral ventricles.

Interventricular foramina

The first and second ventricles are connected to the third ventricle via a foramen interventriculare (also foramen Monroi ) on each side.

Third ventricle

The unpaired III. Ventricle is in the diencephalon below the fornix . It is connected to the lateral ventricles via the Foramina Monroi and flows back ( dorsally ) into the mesencephalic aqueduct , via which it is connected to the fourth ventricle.

The third ventricle is delimited as follows: The floor is formed by the infundibular recess, parts of the optic chiasm , supraoptic recess and midbrain dome (tegmentum mesencephali). The roof is formed by the Tela choroidea ventriculi tertii and the plexus choroideus ventriculi tertii. The anterior wall is formed by the fornicine column , anterior commissure , terminal lamina and the triangular recess. The posterior wall is made up of the commissura habenularum , posterior commissura , suprapineal recess and pineal recess, the side wall is formed by the thalamus , interthalamic adhesions, thalami medullary stria, hypothalamic sulcus and hypothalamus .

Aquaeductus mesencephali

The aqueductus mesencephali connects the third with the fourth ventricle as a narrow channel and crosses the midbrain ( mesencephalon ).

At the transition of the III. Ventricle in the aqueduct is the organum subcommissurale (subcommissural organ) as a circumventricular organ of the epithalamus , below the posterior commissure (commissura epithalamica or posterior). Via the specialized ependymal cells of this developmentally old structure of the neuroepithelium of chordates , among other things, high-molecular secretions are released into the liquor space, which solidify into fibers and aggregate into Reissner's thread .

Fourth ventricle

The fourth ventricle is located in the rhombencephalon (hindbrain) above the rhombus pit and is connected to the subarachnoid space and thus the outer liquor space through a total of three openings - two lateral apertures ( Luschkae foramina ) and one mediana aperture ( Magendii foramen ) .

The floor of the fourth ventricle is formed by the rhombus fossa ( fossa rhomboidea ) as a ventral wall. The tent-like roof ( tegmen ventriculi quarti ) delimit posteriorly in the area of ​​the hindbrain ( metencephalon ): starting from the lamina tecti over the confluence of the aqueductus mesencephali , the unpaired rostral marrow sail ( velum medullare superius ) and following the transverse ridge ( fastigium ) on each side the paired lower medullary sail ( Velum medullare inferius ) and the nodule ("nodule"), a part of the cerebellum, arching in between .

Further caudally, the tela choroidea and plexus choroideus ventriculi quarti form the ventricular roof and finally the obex ("bar"), a transverse medullary lamella at the transition to the central canal of the medullary brain ( canalis centralis medullae oblongatae ). Even in front of this is the median opening (foramen Magendii) as an opening in the ventricular roof, in the corners of the diamond figure at the end of the two lateral recessus laterales there is a lateral opening (foramen Luschkae). They represent important connections in the subarachnoid space as the outer liquor space.

Choroid plexus

The choroid plexus extend in the lateral ventricles from the roof of the lower horns over the pars centralis to the beginning of the anterior horn. They are connected to the choroid plexus of the third ventricle via the interventricular foramina (Monroi). The isolated choroid plexus of the fourth ventricle is located on its roof, caudal to the inferior medullary sail.

See also

Individual evidence

  1. Waldeyer: Anatomie des Menschen . 18th edition. De Gruyter, Berlin 2009, ISBN 978-3-11-019353-4
  2. ^ Pschyrembel Clinical Dictionary . Founded by Willibald Pschyrembel. Edited by the publisher's dictionary editor under the direction of Helmut Hildebrandt. 258th edition. De Gruyter, Berlin 1987, ISBN 3-11-014824-2