Anatomy & Organs

CSF space – structure, function & diseases


The liquor space corresponds to a system of cavities in the central nervous system . In the so-called inner cerebrospinal fluid space, the production of cerebrospinal fluid takes place, which is then reabsorbed in the outer liquor space. Expanded liquor spaces allow pathological phenomena such as hydrocephalus to develop.

What is the liquor space?

The neurologist understands the cerebrospinal fluid to be a system of cavities that run around the brain and spinal cord . This cavity system is filled with a crystal-clear liquid, which is also called liquor or brain water. The fluid in the cerebrospinal fluid constantly flows around the brain and spinal cord.

It plays an increased role in neurological diagnostics, since a liquor sample can be used to determine inflammation and bleeding in the brain, for example. Medicine distinguishes between the inner and outer liquor space. The inner cerebrospinal fluid space is formed by the ventricular system of the brain. The outer CSF space is also known as the subarachnoid space. The Aperturae laterales and the Apertura mediana are openings of the fourth cerebral ventricle. These openings connect the two CSF ​​spaces. The individual rooms of the cavity system are in constant communication. Liquor circulates in it continuously.

Anatomy & Structure

The inner liquor space is located in the central nervous system and results from the cavities of the four brain ventricles, which are located one behind the other. The choroid plexus is located in the inner liquor space. This structure is a convoluted and ateriovenous vascular convulsion in the cerebral ventricles. The canalis centralis completes the inner cerebrospinal fluid space. This guide channel extends down into the spinal cord.

The inner cerebrospinal fluid is also in communication with the spaces of the inner ear . This communication takes place via a fine canal called the aquaeductus cochleae, which contains the watery fluid of the inner ear. The inner ear fluid is also called perilymph. Because of the connection to the inner liquor space, its pressure depends on the pressure behavior of the liquor. The outer liquor space lies between the two meninges, the pia mater and the arachnoid mater. It is slit-shaped and communicates with the inner liquor space via the fourth cerebral ventricle. The arachnoid mater is provided with protuberances, also known as arachnoid villi.

Function & Tasks

The most important task of the liquor space is the production of liquor. In the central nervous system, the cerebrospinal fluid primarily assumes cushioning functions and thus protects the brain and spinal cord. In addition, many scientists assume that the liquor has a nourishing function. The liquid is produced in the choroid plexus of the inner liquor space.

Ultrafiltration takes place there to obtain liquor. This procedure filters the blood of large molecules. In this way, around 0.4 milliliters of liquor form per minute in the inner liquor space. A total of around 120 to 200 milliliters of the brain water formed in this way circulate in an adult human being. However, a total of 500 to 700 milliliters are formed per day. Around 500 milliliters of it are not retained in the CSF but are absorbed. Without this resorption, intracranial pressure would rise dangerously and cause phenomena such as hydrocephalus.

The sodium ions of the ultrafiltrated liquid are therefore actively transported through the plasma membrane of the plexus epithelial cells in the inner CSF space. Finally, the excess liquor is reabsorbed in the outer liquor space. In medicine, absorption means the absorption of certain substances by the body’s own cells or tissues. The protuberances of the arachnoid protrude intracranially into the vein of the dura mater in the outer CSF space. Through this laxative position, they take over the absorption of superfluous brain fluid.


A dangerous event in the liquor space is the so-called subarachnoid hemorrhage . With this phenomenon, blood enters the liquor space. As a result, intracranial pressure increases because too much fluid is circulating in the brain’s cavity system. CSF bleeding is usually due to a ruptured aneurysm . Subarachnoid hemorrhages can be life-threatening and manifest themselves in early symptoms such as stiff neck, impaired consciousness or fainting .

Headaches and blurred vision can also occur. As a rule, the doctor tries to identify the source of the bleeding when this occurs. Ideally, the source can be surgically closed. Only a third of this phenomenon is said to be benign. An even more well-known disease of the cerebrospinal fluid spaces is hydrocephalus, also known as hydrocephalus. In this disease, the liquor spaces are abnormally expanded. Such an expansion is usually related to an overproduction of liquor, as can occur, for example, in the context of meningitis . Congenital malformations of the brain can also cause hydrocephalus.

On the other hand, a tumor can also result in an expansion of the CSF spaces. If such a tumor impedes the circulation of the cerebrospinal fluid, the liquor-carrying cavities may expand to allow the liquor to pass through. If only the inner liquor space is expanded, the neurologist speaks of normal pressure hydrocephalus. The intracranial pressure increases significantly with this phenomenon. The intracranial pressure, on the other hand, remains normal.

This clinical picture is most commonly characterized by gait disorders, but can also lead to incontinence or symptoms of dementia . Congenital enlargements of the liquor spaces are to be distinguished from these phenomena. They can occur, among other things, as part of a subcortical arteriosclerotic encephalopathy , which is also known as Binswanger’s disease.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.