2. INTRODUCTION
• IT IS A MODIFIED TISSUE FLUID PRESENT IN THE
CEREBRAL VENTRICLES, SPINAL CANAL AND
SUBARACHNOID SPACES THUS BATHING THE
ENTIRE NERVOUS SYSTEM.
• THE CENTRAL NERVOUS SYSTEM IS DEVOID OF
LYMPHATICS.
• CEREBROSPINAL FLUID (CSF) REPLACES LYMPH
HERE. IT IS A MODIFIED TISSUE FLUID.
3. CHARACTER
1. IT IS A CLEAR, COLOURLESS, TRANSPARENT FLUID,
DOES NOT COAGULATE ON STANDING.
2. REACTION ALKALINE AND CONTAINS ABOUT 5
LYMPHOCYTES PER CU MM.
3. SPECIFIC GRAVITY 1.004-1.006.
4. PRESSURE 110-130 MM H₂O. PRESSURE RISES ON
STANDING, COUGHING, SNEEZING, CRYING, ETC.
4. • PRESSURE 110-130 MM H₂O (1 DROP PER SECOND THROUGH THE LUMBAR
PUNCTURE NEEDLE). PRESSURE RISES ON STANDING, COUGHING, SNEEZING,
CRYING,
5. FORMATION
1. THE BULK OF THE CSF(2/3RD ) IS FORMED BY THE
CHOROID PLEXUSES OF THE LATERAL VENTRICLES
AND LESSER AMOUNTS(1/3RD ) BY THE CHOROID
PLEXUSES OF THE THIRD AND FOURTH VENTRICLES.
2. IT IS ALSO FORMED BY THE CAPILLARIES ON THE
SURFACE OF THE BRAIN AND SPINAL CORD.
6. • CHOROID PLEXUSES ARE TUFT OF CAPILLARIES COVERED BY EPENDYMA.
• THE ENDOTHELIAL CELLS OF THE CAPILLARIES ARE NOT FLAT AS
ELSEWHERE, BUT ARE GRANULAR AND CUBICAL.
• THIS ARRANGEMENT INDICATES ACTIVE METABOLIC PROCESSES IN THE
CELLS. HENCE, NOT A PASSIVE FILTER.(WILL USE ATP)
• THE SODIUM SECRETED FROM EPENDYMAL CELLS MOVES INTO THE
LATERAL VENTRICLES, THEREBY CREATING OSMOTIC PRESSURE AND
DRAWING WATER INTO THE CSF SPACE.
• THE NEGATIVELY CHARGED CHLORIDE ALSO MOVES WITH THE POSITIVELY
CHARGED SODIUM THUS MAINTAINING NEUTRALITY.
• CSF, THEREFORE, CONTAINS A HIGHER CONCENTRATION OF SODIUM AND
CHLORIDE AND LESS POTASSIUM, CALCIUM, GLUCOSE AND PROTEIN AS
COMPARED TO PLASMA.
7. RATE OF FORMATION
• THE TOTAL QUANTITY OF CSF IS ABOUT 150 ML.
• IT IS FORMED AT THE RATE OF ABOUT 20 ML PER
HOUR OR 500 ML PER DAY.
• THE NORMAL PRESSURE OF CSF IS 60 TO 100 MM
H2O.
8.
9.
10.
11.
12.
13. ABSORPTION OF CSF
1. CSF IS ABSORBED CHIEFLY THROUGH THE ARACHNOID
VILLI AND ARACHNOIDAL GRANULATIONS, AND IS THUS
DRAINED INTO THE CRANIAL VENOUS
SINUSES.(ARACHNOIDE OF PRE VILLI ARE SMALL FINGER-
LIKE PROCESSES PROJECTING INTO THE VENOUS
SINUSES).
2. IT IS ALSO ABSORBED PARTLY BY THE PERINEURAL
LYMPHATICS AROUND THE FIRST, SECOND AND EIGHTH
CRANIAL NERVES.
3. IT IS ALSO ABSORBED BY VEINS RELATED TO SPINAL
14.
15.
16. MECHANISM OF ABSORPTION
• THERE ARE 2 TYPE OF ABSORPTION:
• 1) FILTRATION –PRESSURE OF THE CEREBROSPINAL FLUID IS
HIGHER THAN THAT OF VENOUS BLOOD IN THE CRANIAL
SINUSES. HENCE, ILTHE CEREBROSPINAL FLUID IS FILTERED OUT
INTO THE VEINS.
• 2) OSMOSIS –COLLOIDAL OSMOTIC PRESSURE OF PLASMA IS 25
MM HG AND THE PRESSURE OF CEREBROSPINAL FLUID IS
NEGLIGIBLE. HENCE, CEREBROSPINAL FLUID IS DRAWN INTO THE
SINUSES.
17. FUNCTION OF CSF
1. THE NET WEIGHT OF THE BRAIN SUSPENDED IN THE CSF IS EQUIVALENT
TO A MASS OF 25 G THOUGH THE ACTUAL WEIGHT OF HUMAN BRAIN IS
1400 G. THE BRAIN AND CSF HAVE APPROXIMATELY THE SAME SPECIFIC
GRAVITY, SO THAT THE BRAIN SIMPLY FLOATS IN THE FLUID.
2. CSF DECREASES THE SUDDEN PRESSURE OR FORCES ON DELICATE
NERVOUS TISSUE.
3. CSF NOURISHES NERVOUS TISSUE. ONLY CSF COMES IN CONTACT WITH
NEURONS. EVEN BLOOD CANNOT DIRECTLY COME IN CONTACT WITH
NEURONS. IT PROVIDES NOURISHMENT AND RETURNS PRODUCTS OF
METABOLISM TO THE VENOUS SINUSES.
4. NEURONS CANNOT LIVE WITHOUT GLUCOSE AND OXYGEN FOR MORE
THAN 3-5 MINUTES. THESE ARE CONSTANTLY PROVIDED BY CSF.
18. 5. PINEAL GLAND SECRETIONS REACH PITUITARY GLAND VIA CSF.
6. THERE IS BLOOD-CSF BARRIER. THERE ARE NO ANTIBODIES IN
CNS, MAKING INFECTIONS OF BRAIN VERY SERIOUS ENTITY.
19. CLINICAL ANATOMY
HYDROCEPHALUS: IT IS THE DILATATION OF THE VENTRICULAR SYSTEM AND
OCCURS DUE TO OBSTRUCTION OF CSF CIRCULATION. IT MAY BE OF THE
FOLLOWING TYPES:
1. COMMUNICATING HYDROCEPHALUS: IF THE OBSTRUCTION IS OUTSIDE THE
VENTRICULAR SYSTEM, USUALLY IN THE SUBARACHNOID SPACE OR
ARACHNOID GRANULATIONS, IT IS TERMED AS COMMUNICATING
HYDROCEPHALUS. THIS OCCURS DUE TO FIBROSIS FOLLOWING
MENINGITIS.IT IS ALSO CALLED EXTERNAL HYDROCEPHALUS.
2. NON-COMMUNICATING HYDROCEPHALUS: IF THE OBSTRUCTION IS WITHIN
THE VENTRICULAR SYSTEM, IT IS CALLED NON-COMMUNICATING OR
INTERNAL HYDRO- CEPHALUS. THIS IS USUALLY CAUSED BY A TUMOUR OR
INFLAMMATION.
20.
21. • SYMPTOMS OF HYDROCEPHALUS:
1. HEADACHE
2. VOMITING
3. ATROPHY OF BRAIN
4. MENTAL WEAKNESS
5. CONVULSIONS
22. •LUMBAR PUNCTURE:
• PROCESS BY WHICH CSF IS TAKEN OUT FROM SPINAL
SUBARACHNOID SPACE FOR STUDY.
• AN LP NEEDLE IS INTRODUCED USUALLY BETWEEN 3RD & 4TH
LUMBAR SPINES WITH SUBJECT LYING ON HIS SIDE.
