The cerebral ventricles are the cavities of the brain that produce the vital cerebrospinal fluid. The brain‘s ventricular system consists of a total of four ventricles that communicate with each other and with the outer cerebrospinal fluid space in the connective tissue layer of the spinal cord. One of the most common complaints associated with the cerebral ventricles is a cystic mass in the area of the third ventricle, which can block CSF outflow and initiate intracranial pressure elevation.
What are the cerebral ventricles?
In neurology, the cerebral ventricles are extended cavities in the brain that are filled with cerebrospinal fluid, or brain water. The ventricular system is thus a system of cavities that is broadly divided into four ventricles. In addition to the ventricles of the two cerebral hemispheres, a third ventricle is located in the diencephalon, or interbrain, and the fourth is located in the caudally located rhomcephalon. The individual ventricles differ in their anatomy. They are connected by so-called foramina, i.e. holes, as well as structures such as the aquaeductus mesencephali and are in permanent communication via these connections. The point of attachment of the ventricular system is the central canal of the neural tube, which has formed the individual ventricles through growth processes. All brain ventricles are lined internally. This lining is called ependyma. This is special tissue that is traversed by the so-called choroid plexus. This plexus contains the cerebrospinal fluid. For this reason, the ventricular system is also called the internal cerebrospinal fluid space. This fluid-filled cavity communicates in the region of the fourth ventricle with the outer CSF space, which sits between the arachnoid and pia mater, that is, between the meninges and the connective tissue layer in the spinal cord.
Anatomy and structure
The two ventricles of the cerebrum are composed of anterior horn, middle horn, posterior horn, and inferior horn. The anterior horn base is formed by each of the so-called rostrum corporis callosi. The anterior wall of the structure, on the other hand, forms the genu corporis callosi. The lateral wall forms the caput nuclei caudati. The inner walls are formed by the septum pellucidum, while the truncus corporis callosi forms the roof of each. The stria terminalis, together with the lamina affixa plexus choroideus and the so-called crus fornicis, form the middle part of the two ventricles. The lateral walls are formed by the corpus nuclei caudati and the inner walls by the septum pellucidum and the crus fornicis. The truncus corporis callosi forms the roof of the ventricles. At the floor of the posterior horn, the ventricles terminate with the eminentia collateralis and the trigonum collaterale, while the calcar avis forms the inner boundary and the tapetum the lateral boundary. The subcorneal floor consists of the alveus hippocampi and the eminentia collateralis. The choroid plexus, together with the fimbria hippocampi, forms the inner wall, while the tapetum, together with the cauda nuclei caudati, forms the lateral wall. The lateral wall of the cornu posterius and the cornu inferiuseach also corresponds to the roof of these two structures. The posterior and anterior horns are secondary protrusions and therefore remain entirely free of the choroid plexus. The third ventricle of the diencephalon sits beneath the fornix and is formed at the base by portions of the optic chiasm, the infundibular and supraoptic recesses, and the midbrain cap. The ventricular choroid plexus tertii and the ventricular choroid tela form the roof, while the commissura anterior, columna fornicis, lamina terminalis, and recessus triangularis form the anterior wall. The posterior wall of the third ventricle consists of the commissura posterior, the commissura habenularum, the recessus suprapinealis, and the recessus pinealis. The thalamus, together with the stria medullaris thalami, the adhaesio interthalamica, and the sulcus hypothalamicus and hypothalamus, form the lateral wall. The fourth ventricle of the rhombencephalon is located in the rhomboid fossa and is bounded by the cerebellar cones, obex, and tela choroidea, as well as the ventriculi quarti, nodulus, and fastigium. Unlike the rest, this ventricle has three openings that connect to the external CSF space and provide CSF drainage.
Function and Tasks
The most important function of the cerebral ventricular system is to carry cerebrospinal fluid. The CSF serves as protection from impact, friction, and pressure.Apart from this, the cerebrospinal fluid nourishes the entire brain as well as the spinal cord with glucose. It also removes metabolic products from the brain space and serves as thermal protection for the brain system. The capillary plexuses, i.e., the choroid plexus of the ventricular system, form the vital cerebrospinal fluid from blood plasma via filtration and secretion processes. In total, the ventricular system produces between 500 and 700 milliliters of cerebrospinal fluid per day, with reabsorption processes in the radices spinales and the granulationes arachnoideales permanently maintaining the circulating volume of cerebrospinal fluid at about 150 milliliters. The cerebrospinal fluid drains from the ventricular system into the external cerebrospinal fluid space. This task of the system is also vital and can lead to pathological changes in the brain if it malfunctions. CSF is also clinically relevant with regard to CSF diagnostics, in which cerebrospinal fluid is drawn from the outer CSF space to investigate diseases of the central nervous system.
Diseases
One of the most common diseases associated with the cerebral ventricular system is colloid cyst, which corresponds to a benign cystic structure in the third ventricle of the brain. When the cystic structures displace the foramen Monroi, CSF congestion occurs. Such liguor congestion increases intracranial pressure and may be fatal. To prevent this, colloid cysts are removed with minimally invasive neuroendoscopic procedures. In addition to these cyst formations, pathological dilation of the cerebrospinal fluid (CSF) spaces can occur in association with the ventricles, usually preceded by overproduction of cerebrospinal fluid. Such overproduction may be associated with space-occupying lesions such as tumors or blood clots. However, an inflammatory process in the central nervous system or the destruction of brain tissue may also be responsible for the phenomenon. Increased intracranial pressure is also often present in this condition. The course of treatment depends on what has caused the cerebrospinal fluid overproduction.
Typical and common brain diseases
- Dementia
- Creutzfeldt-Jakob disease
- Memory gaps
- Brain hemorrhage
- Meningitis
