cerebrospinal fluid

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pertaining to the brain and spinal cord.
cerebrospinal fluid the fluid within the subarachnoid space, the central canal of the spinal cord, and the four ventricles of the brain. The fluid is formed continuously by the choroid plexus in the ventricles, and, so that there will not be an abnormal increase in amount and pressure, it is reabsorbed into the blood by the arachnoid villi at approximately the same rate at which it is produced.

The cerebrospinal fluid aids in the protection of the brain, spinal cord, and meninges by acting as a watery cushion surrounding them to absorb the shocks to which they are exposed. There is a blood-cerebrospinal fluid barrier that prevents harmful substances, such as metal poisons, some pathogenic organisms, and certain drugs from passing from the capillaries into the cerebrospinal fluid.

The normal cerebrospinal fluid pressure is 5 mm Hg (100 mm H2O) when the individual is lying in a horizontal position on his side. Fluid pressure may be increased by a brain tumor or by hemorrhage or infection in the cranium. hydrocephalus, or excess fluid in the cranial cavity, can result from either excessive formation or poor absorption of cerebrospinal fluid. Blockage of the flow of fluid in the spinal canal may result from a tumor, blood clot, or severance of the spinal cord. The pressure remains normal or decreases below the point of obstruction but increases above that point.

Cell counts, bacterial smears, and cultures of samples of cerebrospinal fluid are done when an inflammatory process or infection of the meninges is suspected. Since the cerebrospinal fluid contains nutrient substances such as glucose, proteins, and sodium chloride, and also some waste products such as urea, it is believed to play a role in metabolism. The major constituents of cerebrospinal fluid are water, glucose, sodium chloride, and protein. Information about changes in their concentrations is helpful in diagnosis of brain diseases.

Samples of cerebrospinal fluid may be obtained by lumbar puncture, in which a hollow needle is inserted between two lumbar vertebrae (below the lower end of the spinal cord), or into the cisterna cerebellomedullaris just below the occipital bone of the skull (cisternal puncture). Pressure of the cerebrospinal fluid is measured by a manometer attached to the end of the needle after it has been inserted.

cer·e·bro·spi·nal flu·id (CSF),

a fluid largely secreted by the choroid plexuses of the ventricles of the brain, filling the ventricles and the subarachnoid cavities of the brain and spinal cord.
Synonym(s): liquor cerebrospinalis [TA]

cerebrospinal fluid

The serumlike fluid that circulates through the ventricles of the brain, the cavity of the spinal cord, and the subarachnoid space, functioning in shock absorption. Also called spinal fluid.

cerebrospinal fluid (CSF)

the fluid that flows through and protects the four ventricles of the brain, the subarachnoid spaces, and the spinal canal. It is composed mainly of secretions of the choroid plexuses in the lateral ventricles and in the third and the fourth ventricles of the brain and is clear and colorless. Changes in the carbon dioxide content of CSF affect the respiratory center in the medulla, helping to control breathing. A brain tumor may press against the cerebral aqueduct and shut off the flow of the fluid from the third to the fourth ventricle, causing fluid accumulation in the lateral and third ventricles, called internal hydrocephalus. Other blockages of the flow of CSF, such as those caused by blood clots, result in serious complications. Certain illnesses and various diagnoses may require microscopic examination and chemical analysis of CSF. Samples of the fluid may be removed by lumbar puncture between the third and the fourth lumbar vertebrae or from the cisterna magna.
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Cerebrospinal fluid circulation

cerebrospinal fluid

Spinal fluid Neurology A clear, colorless fluid that contains small quantities of glucose and protein, which surrounds the brain, spinal cord, ventricles, subarachnoid space, and the central canal of the spinal cord, provides nutrients, and acts as a shock absorber; CSF analysis is accomplished by lumbar puncture; WBCs or bacteria in the CSF indicate bacterial–septic meningitis. See Lumbar puncture.

cer·e·bro·spi·nal flu·id

(CSF) (ser'ĕ-brō-spī'năl flū'id) [TA]
A fluid largely secreted by the choroid plexuses of the ventricles of the brain, filling the ventricles and the subarachnoid cavities of the brain and spinal cord.
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cerebrospinal fluid

Abbreviation: CSF
The sodium-rich, potassium-poor tissue fluid of the brain and spinal cord. The fluid supplies nutrients and removes waste products; it is also a watery cushion that absorbs mechanical shock to the central nervous system. Synonym: spinal fluid See: lumbar puncture


The fluid is formed by the choroid plexuses of the lateral and third ventricles. That of the lateral ventricles passes through the foramen of Monro to the third ventricle, and through the aqueduct of Sylvius to the fourth ventricle. There it may escape through the central foramen of Magendie or the lateral foramina of Luschke into the cisterna magna and to the cranial and spinal subarachnoid spaces. It is reabsorbed through the arachnoid villi into the blood in the cranial venous sinuses, and through the perineural lymph spaces of both the brain and the cord. See: illustration


The fluid is normally watery, clear, colorless, and almost entirely free of cells. The initial pressure of spinal fluid in a side-lying adult is about 100 to 180 mm of water. On average, the total protein is about 15 to 50 mg/dL, and the concentration of glucose is about twothirds the concentration of glucose in the patient's serum. Its pH, which is rarely measured clinically, is slightly more acidic than the pH of blood. Its concentration and alkaline reserve are similar to those of blood. It does not clot on standing. Turbidity suggests an excessively high number of cells in the fluid, typically white blood cells in infections such as meningitis or red blood cells in intracerebral hemorrhage.

CSF may appear red following a recent subarachnoid hemorrhage or when the lumbar puncture that obtained the CSF caused traumatic injury to the dura that surround the fluid. Centrifugation of the fluid can distinguish between these two sources of blood in the spinal fluid: the supernatant is usually stained yellow (xanthochromic) only when there has been a recent subarachnoid hemorrhage.

Many conditions may cause increases in CSF total protein: infections, such as acute or chronic meningitis; multiple sclerosis (when oligoclonal protein bands are present); Guillain-Barré syndrome; and chronic medical conditions like cirrhosis and hypothyroidism (when diffuse hypergammaglobulinemia is present). The concentration of glucose in the CSF rises in uncontrolled diabetes mellitus and drops precipitously in meningitis, sarcoidosis, and some other illnesses. Malignant cells in the CSF, demonstrated after centrifugation or filtering, are hallmarks of carcinomatous meningitis.


The CSF is normally sterile. Meningococci, streptococci, Haemophilus influenzae, Listeria monocytogenes, and gram-negative bacilli are recovered from the CSF only in cases of meningitis. Syphilitic meningitis is usually diagnosed with serological tests for the disease, such as the venereal disease research laboratory (VDRL) test, the rapid plasma reagin (RPR) test, or the fluorescent treponemal antibody test. Cryptococcal infection of the CSF may be demonstrated by India ink preparations, or by latex agglutination tests. Tuberculous meningitis may sometimes be diagnosed with Ziehl-Neelsen stains, but more often this is done with cultures. These last three infections (syphilis, cryptococcosis, and tuberculosis) are much more common in patients who have acquired immunodeficiency syndrome (AIDS) than in the general population.

See also: fluid

cerebrospinal fluid

The watery fluid that bathes the brain and spinal cord and also circulates within the ventricles of the brain and the central canal of the cord.

cerebrospinal fluid (CSF)

a solution secreted by the CHOROID PLEXUSES (one in the roof of each of the four brain VENTRICLES (2) in man) which fills the cavity of the brain and SPINAL CORD and the space between the CENTRAL NERVOUS SYSTEM and its ensheathing membrane. It contains most of the small molecules found in blood, e.g. salts and glucose, but little protein and few cells, and serves as a nutritive medium. In humans the total volume is about 100 cm3.

Cerebrospinal fluid (CSF)

Fluid produced within the brain for nutrient transport and structural purposes. CSF circulates through the ventricles, open spaces within the brain, and drains through the membranes surrounding the brain.

cerebrospinal fluid

fluid surrounding the brain and spinal cord

cerebrospinal fluid (s·rēˈ·brō·spīˑ·nl flōōˑ·id),

n colorless, clear fluid that surrounds the central nervous system, that absorbs shocks, delivers nutrients, and removes waste products.
Enlarge picture
Cerebrospinal fluid.

cer·e·bro·spi·nal flu·id

(CSF) (ser'ĕ-brō-spī'năl flū'id) [TA]
A fluid largely secreted by the choroid plexuses of the ventricles of the brain, filling the ventricles and the subarachnoid cavities of the brain and spinal cord.

cerebrospinal fluid,

n the fluid that flows through and protects the four ventricles of the brain, subarachnoid space, and spinal canal.


1. a liquid or gas; any liquid of the body.
2. composed of molecules which freely change their relative positions without separation of the mass.

allantoic fluid
the fluid contained within the allantois.
amniotic fluid
the fluid within the amnion that bathes the developing fetus and protects it from mechanical injury.
ascitic fluid
see ascites.
fluid balance
a state in which the volume of body water and its solutes (electrolytes and nonelectrolytes) are within normal limits and there is normal distribution of fluids within the intracellular and extracellular compartments. The total volume of body fluids should be about 60% of the body weight, and it should be distributed so that one-third is extracellular fluid and two-thirds intracellular fluid. Although this distribution remains constant in a healthy animal, there is continuous movement of fluid into and out of the various compartments. See also dehydration, water intoxication.
body f's
the fluids within the body, composed of water, electrolytes and nonelectrolytes. The volume and distribution of body fluids vary with age, sex and amount of adipose tissue. Throughout life there is a slow decline in the volume of body fluids; obesity decreases the relative amount of water in the body.
Although the body fluids are continuously in motion, moving in and out of the cells, tissue spaces and vascular system, physiologists consider them to be 'compartmentalized'. Fluid within the cell membranes is called intracellular fluid and comprises about two-thirds of the total body fluids. The remaining one-third is outside the cell and is called extracellular fluid. The extracellular fluid can be further divided into tissue fluid (interstitial fluid), which is found in the spaces between the blood vessels and surrounding cells, and intravascular fluid, which is the fluid component of blood.
The maintenance of a proper balance between the intracellular and extracellular fluid volumes is essential to health. In patients with heart failure and renal failure the balance becomes upset, producing either localized or generalized edema. Excessive fluid loss produces fluid volume deficit causing cellular dehydration and impaired cellular function.
Bouin's fluid
a histological fixative.
cerebrospinal fluid
the fluid contained within the ventricles of the brain, the subarachnoid space, and the central canal of the spinal cord. See also cerebrospinal fluid.
fluid dram
see fluid dram.
fluid extract
a liquid preparation of a vegetable drug, containing alcohol as a solvent or preservative, or both, of such strength that each milliliter contains the therapeutic constituents of 1 gram of the standard drug it represents.
fetal fluid
allantoic plus amniotic fluids.
interstitial fluid
the extracellular fluid bathing the cells in most tissues, excluding the fluid within the lymph and blood vessels.
isotonic fluid
having the same tonicity or osmotic pressure as blood.
lacrimal fluid
aqueous fluid secreted by the lacrimal glands; called also tears.
fluid line
in radiographs, the interface between fluid and gas, as in the gastrointestinal tract, will show as a straight line.
fluid loss
by vomiting, diarrhea, polyuria, water deprivation. See dehydration.
fluid mosaic model
the modern concept of the structure of a biological membrane developed by S.J. Singer and G.L. Nicolson. In it the membrane consists of protein molecules partly embedded in a discontinuous bilayer of phospholipids that form the matrix of a mosaic of functional cell units.
fluid ounce
see fluid ounce.
pericardial, pleural, peritoneal fluid
normally present in amounts sufficient only to lubricate the movement of viscera within the respective cavities. Composition similar to blood serum.
fluid replacement
see fluid therapy (below).
fluid restriction
the limitation of oral fluid intake to a prescribed amount for each 24-hour period.
fluid retention
see edema.
spinal fluid
the fluid within the spinal canal.
fluid splashing sounds
audible when gas and fluid are free in a cavity, e.g. abomasum in cases of abomasal displacement; can be elicited by shaking a small animal or part of a large animal (i.e. succussion) or by simultaneous percussion and auscultation.
synovial fluid
fluid therapy
aims to replace fluids lost by disease process or by restriction of intake, or to maintain a high rate of fluid excretion to ensure removal of toxins, or to administer therapeutic or anesthetic agents slowly over a long period. The amounts and route of administration vary with the need of the patient. Normal solutions include 5% dextrose and Ringer's solution; alkalinizing fluids include lactated Ringer's and 1.3% sodium bicarbonate; acidifying solutions include isotonic saline and 1.9% ammonium chloride.
fluid thrill
see thrill.
fluid volume deficit
an imbalance in fluid volume in which there is loss of fluid from the body not compensated for by an adequate intake of water. The major causes are: (1) insufficient fluid intake, and (2) excessive fluid loss from vomiting, diarrhea, suctioning of gastric contents, or drainage through operative wounds, burns or fistulae. Decreased volume in the intravascular compartment is called hypovolemia. Because water moves freely between the compartments, extracellular fluid deficit causes intracellular fluid deficit (cellular dehydration), which leaves the cells without adequate water to carry on normal function.
fluid volume excess
an overabundance of water in the interstitial fluid spaces or body cavities (edema) or an excess of fluid within the blood vessels (hypervolemia) and water intoxication.
Factors that contribute to the accumulation of edematous fluid are: (1) dilatation of the arteries, as occurs in the inflammatory process; (2) reduced effective osmotic pressure, as in hypoproteinemia, lymphatic obstruction and increased capillary permeability; (3) increased venous pressure, as in congestive heart failure, thrombophlebitis and cirrhosis of the liver; and (4) retention of sodium due to increased reabsorption of sodium by the renal tubules.
fluid wave
see thrill.
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