Cerebrospinal fluid

A clear liquid stays inside your head.

It flows around your brain and your spine. This liquid works like a soft cushion. It helps protect your brain if you get hit.

Your body makes this liquid every day. Tiny parts in your brain help make it. The liquid moves in a steady flow. It also helps wash away waste. This keeps your brain healthy and clean.

It is a very important liquid!

A clear liquid lives inside your head and spine. This liquid is called cerebrospinal fluid, or CSF.

It helps keep your brain safe. The brain is heavy. CSF makes it feel light so it can float. This is called buoyancy. It also acts like a cushion. It protects the brain if you get hit.

Your body makes about 500 mL of CSF every day. Most of it comes from the choroid plexus. This is a network of blood vessels in the brain. These vessels make the fluid in two steps. First, fluid moves from the blood. Then, cells move salt and water into the brain's open spaces. These spaces are called ventricles.

The fluid moves in a steady flow. Tiny hairs called cilia beat to move it along. This flow helps wash away waste from the brain. It also helps keep the right amount of blood in the brain. Doctors can test CSF to look for infections. They do this by taking a sample near the spine.

Cerebrospinal fluid, or CSF, is a clear and colorless liquid. It lives in the spaces around your brain and spinal cord.

This fluid is very important for your body. It acts like a cushion or a shock absorber. This protects your brain if you get a sudden jolt or hit. CSF also helps your brain float in a state called buoyancy. The brain is quite heavy, weighing about 1400 to 1500 grams.

Because it floats in CSF, its weight feels much lower. This helps keep blood flowing well to your neurons.

Your body follows a special way it works to make this fluid. Most of the CSF is made in the choroid plexus. This is a network of blood vessels found inside the brain's ventricles.

The process happens in two main steps. First, a filtered version of blood plasma moves into a small space. Next, cells move salt and water into the brain's open spaces. This creates osmotic pressure that pulls the water in. Tiny hairs called cilia beat to help move the fluid along. This movement keeps the liquid flowing through the whole system.

People have known about this fluid for a very long time. The famous thinker Hippocrates noted it in the past. However, many people forgot about it for many centuries. In the 18th century, a man named Emanuel Swedenborg described it again. Later, in 1914, a scientist named Harvey Cushing showed how it is made. He proved that the choroid plexus is what secretes the fluid. These discoveries helped us understand how the brain stays healthy every day.

There are many interesting numbers to know about CSF. A human body has about 125 to 150 mL of CSF at any time. Even though there is not much at once, the body makes about 500 mL every single day. This means the fluid is constantly being made and then reabsorbed. In infants, there is more CSF for every kilogram of body weight than in adults. In adults, the amount is about 1.5 to 2 mL per kilogram. This constant cycle helps keep the brain's environment very stable.

This fluid is a lot like the plasma in your blood. It is mostly water, but it has different levels of salt and sugar. For example, it has a higher sodium level than blood plasma. The flow of CSF also helps clean the brain. It works like a washing system to remove waste products. This is part of a system called the glymphatic system. By moving waste into the bloodstream, the CSF keeps the brain from becoming toxic. It is a vital part of how your whole body stays well.

Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the meningeal tissue. This tissue surrounds the vertebrate brain and spinal cord. CSF also fills the ventricles, which are a series of cavities inside the brain. This fluid is vital for maintaining a healthy central nervous system. It provides mechanical and immunological protection to the brain inside the skull.

Without this constant circulation, the brain could not function properly.

The mechanism of CSF production is a precise two-step process. Most of the fluid is produced by the choroid plexus. This is a network of blood vessels located within the brain's ventricles. First, a filtered form of blood plasma moves from fenestrated capillaries into an interstitial space. This movement is guided by pressure differences between the blood and the interstitial fluid. Second, epithelial cells move sodium, potassium, and chloride into the ventricles. This active transport creates osmotic pressure, which draws water into the CSF through aquaporins.

Tiny, motile cilia on the surface of ependymal cells beat to move the fluid through the ventricles.

CSF circulates through a specific path within the ventricular system. The majority of production happens in the two lateral ventricles. From there, the fluid passes through the interventricular foramina into the third ventricle. It then moves through the cerebral aqueduct to reach the fourth ventricle. From the fourth ventricle, the fluid enters the subarachnoid space. It does this through four openings: the central canal of the spinal cord, the median aperture, and two lateral apertures. The subarachnoid space is the area between the arachnoid mater and the pia mater.

In 93% of people, this space is continuous with the perilymph in the inner ear.

History shows that our understanding of CSF has changed over many centuries. The ancient thinker Hippocrates noted the fluid, but the topic was later forgotten. It was described again in the 18th century by Emanuel Swedenborg. A major breakthrough occurred in 1914 when Harvey Cushing demonstrated how the fluid is made. He proved that the choroid plexus is responsible for secreting the CSF. These discoveries allowed scientists to study how the brain regulates its own environment.

There are many important numbers regarding CSF volume and mass. A human typically has about 125 to 150 mL of CSF present at any one time. However, the body generates about 500 mL of new fluid every single day. This means the fluid is constantly being produced and reabsorbed. The volume also varies by age. Infants have about 4 mL of CSF per kilogram of body weight. Children have 3 mL/kg, while adults have only 1.5 to 2 mL/kg. This higher volume in children may be why they have lower rates of postdural puncture headaches.

The physical properties of CSF provide essential functions like buoyancy and protection. The human brain has a mass of about 1400 to 1500 grams. However, when suspended in CSF, its net weight is only 25 to 50 grams. This neutral buoyancy prevents the brain's own weight from cutting off blood supply to lower neurons. Additionally, CSF acts as a shock absorber to protect against mechanical injury. It also helps prevent brain ischemia by helping to regulate intracranial pressure. This allows blood to flow properly through the brain.

Finally, CSF is critical for waste removal and chemical balance. It is derived from blood plasma but is nearly protein-free. It contains different electrolyte levels, such as higher sodium and lower chloride than plasma. The fluid moves metabolic waste products out of the brain through the glymphatic system. This system is the brain's version of a lymphatic system. As CSF flows, waste products diffuse into it and are eventually removed into the bloodstream. If this process fails, the brain can become toxic, which is seen in diseases like amyotrophic lateral sclerosis.