Ventricular system of brain
The ventricular system forms the cavities of the central nervous system and is filled with cerebrospinal fluid . It arises from the original cavity of the neural tube, which in the spinal cord is transformed into the canalis centralis medullae spinalis and in the base of the brain expands into the cerebral ventricles ( ventriculi cerebri ). These are designated in order in the CNS in the caudocranial direction as ventriculus quartus , ventriculus tertius and ventriculus lateralis dexter et sinister .
Ventricles of the brain[edit | edit source]
Fourth Ventricle (IV. cerebral ventricle)[edit | edit source]
It is an unpaired cavity, the base of which is formed by the dorsal surface of the brainstem , the so-called fossa rhomboidea , the roof is formed by the cerebellum and other components, laterally the ventricle then extends as recessus lateralis ventriculi quarti . On the base of the IV. ventricle, into the fossa rhomboidea , the nuclei of the cranial nerves are projected . The areas of the motor and sensitive nuclei are separated by the sulcus limitans . Two rows of somatomotor nuclei lie medially. The row of nuclei closer to the sulcus medianus is formed by ncl. III. , IV. , VI. , XII. and laterally from them are located ncl. V. , VII. and ncl. ambiguus , to which visceromotor nuclei are connected , sending fibers to smooth muscles and glands. These are ncl. oculomotorius accesorius , ncl. salivatorius superior et inferior and ncl. dorsalis n. vagi . Laterally from the sulcus limitans lies the only viscerosensitive nucleus ncl. solitarius , completely laterally are the somatosensitive nuclei – ncl. spinalis et pontinus n. V. and the sensory nuclei ncll. vestibulares et cochleares . The nuclei of the reticular formation are also arranged in three longitudinal stripes in the fossa rhomboidea .
Third ventricle (III. cerebral ventricle)[edit | edit source]
It is an unpaired cavity in the diencephalon , closed on the sides by the thalamus and the right and left halves of the hypothalamus , which form its floor. The connection of the right and left thalamus, the adhaesio interthalamica , passes through the center of the ventricle .
Lateral ventricles (lateral cerebral ventricles)[edit | edit source]
They are paired horseshoe-shaped cavities located in the right and left cerebral hemispheres. We can also refer to them as the I. and II. cerebral ventricles. We distinguish 4 sections in each. The cornu frontale arches into the frontal lobe , continues as the pars centralis , which runs above the III. cerebral ventricle. Next is the cornu occipitale extending into the occipital lobe and the last section is the cornu temporale , which is located in the temporal lobe and on whose basal wall lies the hippocampus .
Liquor cerebrospinalis (cerebrospinal fluid)[edit | edit source]
Cerebrospinal fluid is formed in all four cerebral ventricles in the choroid plexus. These grape-like formations arise from the vascular plexus. From the lateral ventricles, the liquor flows through the foramen interventriculare into the III. ventricle and from there through the aquaeductus mesencephali , the so-called Sylvian canal, into the IV. ventricle . From the IV ventricle, it is distributed through the apertura mediana , the so-called foramen Magendi , et aperturae laterales ventriculi quarti ( foramina Luschkae ) into the subarachnoideal space (spatium subarachnoideum) of the brain and spinal cord and into the canalis centralis medullae spinalis . From the spatium subarachnoideum, the liquor is then absorbed into the veins on the surface of the CNS and through them it reaches the plexus venosi vertebrales interni in the spinal canal , in the skull into the sinus durae matris – most often into the sinus sagittalis superior . The absorption of the liquor involves the processes of the arachnoid – granulationes arachnoideae . Reduced resorption of cerebrospinal fluid leads to increased intracranial pressure and hydrocephalus occurs . The total amount of cerebrospinal fluid is 150 ml . However, about 500 ml is produced daily in the choroid plexus . Its main functions include buoyancy and protection of the brain - it balances pressure changes caused by arterial pulsation. It contains proteins, glucose, lymphocytes and other substances and therefore also has a nutritional and immunological function .
For more detailed information, see the cerebrospinal fluid page
Links[edit | edit source]
Related articles[edit | edit source]
External Links[edit | edit source]
- The Ventricular System, National Center for Biotechnology Information
- Ventricles of the Brain, Maedscape
