Protection– acts as a cushion for the brain, limiting neural damage in cranial injuries.
Buoyancy– by being immersed in CSF, the net weight of the brain is reduced to approximately 25 grams. This prevents excessive pressure on the base of the brain.
Chemical stability– the CSF creates an environment to allow for proper functioning of the brain, e.g. maintaining low extracellular K+ for synaptic transmission.
Fig 1 Overview of the cerebrospinal fluid distribution in the brain
Ventricles of the Brain
The ventricles are structures that produce cerebrospinal fluid, and transport itaround the cranial cavity. They are lined by ependymal cells, which form a structure called the choroid plexus. It is within the choroid plexus that CSF is produced.
Embryologically, the ventricular system is derived from the lumen of the neural tube.
In total, there are four ventricles – right and left lateral ventricles, third ventricle and fourth ventricle.
Lateral Ventricles
The left and right lateral ventricles are located within their respective hemispheres of the cerebrum. Theyhave ‘horns’ which project into the frontal, occipital and temporal lobes. The volume of the lateral ventricles increases with age.
Fig 2 Bird’s eye view of a cast of the ventricular system of the brain.
Third Ventricle
The lateral ventricles are connected to the third ventricle by the foramen of Monro. The third ventricle is situated in between the right and the left thalamus. The anterior surface of the ventricle contains two protrusions:
Supra-optic recess – located above the optic chiasm.
Infundibular recess– located above the optic stalk.
Fourth Ventricle
The fourth ventricle is the last in the system – it receives CSF from the third ventricle via the cerebral aqueduct. It lies within the brainstem, at the junction between the pons and medulla oblongata.
From the 4th ventricle, the fluid drains into two places:
Central spinal canal – bathes the spinal cord
Subarachnoid cisterns – bathes the brain, between arachnoid mater and pia mater. Here the CSF is reabsorbed back into the circulation.
Fig 3 The anatomical positioning of the ventricles of the brain.
Production and Reabsorption of Cerebrospinal Fluid
Cerebrospinal fluid is produced by the choroid plexus, located in the lining of the ventricles. It consists of capillaries and loose connective tissue, surrounded by cuboidal epithelial cells. Plasma is filtered from the blood by the epithelial cells to produce CSF. In this way, the exact chemical composition of the fluid can be controlled.
Drainage of the CSF occurs in the subarachnoid cisterns (or space). Small projections of arachnoid mater (arachnoid granulations) protrude into the dura mater. They allow the fluid to drain into the dural venous sinuses.
Learn more about the production and reabsorption of cerebrospinal fluid here.
Fig 4 Coronal section of the skull, meninges and cerebrum. An arachnoid granulation is visible in the centre.
Clinical Relevance
Hydrocephalus
Hydrocephalus is defined as an abnormal collection of cerebrospinal fluid within the ventricles of the brain. It is a serious condition, with chronic hydrocephalus causing raised intracranial pressure, and consequently cerebral atrophy.
Based on the underlying cause, there are two clinical classifications:
Communicating (Non-obstructive) Hydrocephalus – Abnormal collection of CSF in the absence of any flow obstruction in the ventricles. Common causes usually involve the functional impairment of the arachnoid granulations, such as fibrosis of the subarachnoid space following a haemorrhage.
Non-communicating (Obstructive) Hydrocephalus – Abnormal collection of CSF, with flow obstructed within the ventricular system. The most common site of obstruction is the cerebral aqueduct, connecting the third and fourth ventricles.
By Lucien Monfils [CC-BY-SA-3.0-2.5-2.0-1.0], via Wikimedia Commons
Fig 5 Hydrocephalus on a CT scan.
There is also a third classification, hydrocephalus ex vacuo– this refers to ventricular expansion, secondary to brain atrophy. This is often seen in patients with neurodegenerative conditions, such as Alzheimer’s disease.
Treatment of hydrocephalus primarily involves reversing the cause. Whilst treating the cause, a shunt can be inserted, which drains the fluid into the right atrium or the peritoneum.
The cerebral ventricular system is made up of 4 ventricles that include 2 lateral ventricles
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.
https://en.wikipedia.org › wiki › Lateral_ventricles
(1 in each cerebral hemisphere), the third ventricle in the diencephalon, and the fourth ventricle in the hindbrain. Inferiorly, it is continuous with the central canal of the spinal cord.
The main function of this ventricle is to protect the human brain from trauma (via a cushioning effect) and to help form the central canal, which runs the length of the spinal cord.
The third and fourth ventricles of the brain are connected by cerebral aqueduct, which is a canal that passes through the midbrain. It is also known as the aqueduct of Sylvius.
The cerebral aqueduct (of Sylvius) is a narrow channel connecting the third and fourth brain ventricles. Normally, cerebrospinal fluid flows through the aqueduct with no obstruction, but when a blockage occurs, stenosis can lead to symptoms of hydrocephalus.
The cerebral ventricular system is made up of 4 ventricles that include 2 lateral ventricles (1 in each cerebral hemisphere), the third ventricle in the diencephalon, and the fourth ventricle in the hindbrain. Inferiorly, it is continuous with the central canal of the spinal cord.
Hydrocephalus is a neurological disorder caused by an abnormal buildup of cerebrospinal fluid in the ventricles (cavities) deep within the brain. This excess fluid causes the ventricles to widen, putting harmful pressure on the brain's tissues.
It is connected at the superior anterior corner to the lateral ventricles, by the interventricular foramina, and becomes the cerebral aqueduct (aqueduct of Sylvius) at the posterior caudal corner.
The fourth ventricle has a roof 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 key function of the ventricular system is the production and recycling of Cerebrospinal Fluid (CSF) throughout the central nervous system including the brain and the spinal cord.
The structures in the brain that the 4 ventricles and the cerebral aqueduct are associated with are the forebrain, midbrain, and hindbrain. The lateral ventricle is found in the telencephalon (forebrain).
Name and locate the ventricles of the brain. . The lateral ventricles are in the cerebral hemispheres; the third ventricle is in the diencephalon; the fouth ventricle is between the brain stem and the cerebellum and connects with the central canal of the spinal cord.
The cerebral aqueduct is a narrow 15 mm conduit that allows for cerebrospinal fluid (CSF) to flow between the third ventricle and the fourth ventricle.
The lateral ventricles are connected to the third ventricle by an interventricular foramen, and the third ventricle connects to the fourth through the cerebral aqueduct (also called the aqueduct of Sylvius).
Your brain floats in a bath of cerebrospinal fluid. This fluid also fills large open structures, called ventricles, which lie deep inside your brain. The fluid-filled ventricles help keep the brain buoyant and cushioned.
The principal role of the ventricles is to pump blood out of the heart and into either systemic or pulmonary circulation. During diastole (relaxation) the ventricle is in the phase of passive filling where blood passes through the atria and into the ventricles.
The fourth ventricle communicates with the subarachnoid space through the lateral foramen of Luschka, located near the flocculus of the cerebellum, and through the median foramen of Magendie, located in the roof of the ventricle. Most of the CSF outflow passes through the medial foramen.
The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes (Figure 2). The frontal lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus. The frontal lobe is involved in reasoning, motor control, emotion, and language.
Aside from cerebrospinal fluid, your brain ventricles are hollow. Their sole function is to produce and secrete cerebrospinal fluid to protect and maintain your central nervous system.
Introduction: My name is Allyn Kozey, I am a outstanding, colorful, adventurous, encouraging, zealous, tender, helpful person who loves writing and wants to share my knowledge and understanding with you.
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