cerebrospinal fluid

1. CEREBROSPINAL
FLUID

2. INTRODUCTIO
N
•The CSF is found in the
•ventricles, Subarachnoid space & Spinal
cord.
•It has a volume of about 150 ml.
•It is a clear, colorless fluid.

4. The CSF contributes to homeostasis in three main ways:
1. Mechanical protection.
• CSF serves as a shock-absorbing Medium that protects the
delicate tissues of the brain and
• spinal Cord from jolts that cause them to hit the bony walls
of the cranial cavity and vertebral canal.
• The fluid also Buoys the brain so that it “floats” in the
cranial cavity.

5. 2. Chemical protection.
•CSF provides an optimal chemical Environment
for accurate neuronal signaling.
•Even slight Changes in the ionic composition of
CSF within the brain can Seriously disrupt
production of action potentials and Postsynaptic
Potentials.

6. 3. Circulation.
CSF allows exchange of nutrients and waste Products
between the blood and nervous tissue.

7. Composition of
CSF

11. FORMATION OF CEREBROSPINAL FLUID
SITE OF FORMATION
•CSF is formed by choroid plexuses, situated within the
ventricles.
•Choroid plexuses are tuft of capillary projections present
inside the ventricles.
•It’s covered by pia mater and ependymal covering.
•Alarge amount of CSF is formed in the lateral ventricles.

12. MECHANISM OF
FORMATION OF CSF
CSF is formed primarily by secretion and also by filtration from the net works of
capillaries and ependymal cells in the ventricles called choroid plexus.
Various components of the choroid plexus from a blood-cerebrospinal fluid barrier
that permits certain substances to enter the fluid, but prohibits others.
Such a barrier protects the brain and spinal cord from harmful substances.

13. MECHANISM OF
FORMATION OF CSF
The entire cerebral cavity enclosing the brain and spinal cord has a
capacity of about 1600 to 1700 milliliters
About 150 milliliters of this capacity is occupied by cerebrospinal fluid
and the remainder by the brain and cord.

14. MECHANISM OF
FORMATION OF CSF
Rate of formation:
About 20-25 ml/hour
550 ml/day in adults. Turns over 3.7 times a day
Total quantity: 150 ml:
30-40 ml within the ventricles
About 110-120 ml in the subarachnoid space [of which 75-80 ml in spinal part and
25-30 ml in the cranial part].

15. MECHANISM OF
FORMATION
CSF is formed at a rate of about 550 milliliters each day,. About two thirds or more of
this fluid originates as secretion from the choroid plexuses in the four ventricles,
mainly in the two lateral ventricles.
Additional small amount of fluid is secreted by the ependymal surfaces of all the
ventricles and by the arachnoidal membranes
Small quantity comes from the brain itself through the perivascular spaces that
surround the blood vessels passing through the brain.

16. MECHANISM OF
FORMATION
Secretion by the Choroid Plexus. The choroid plexus, is a cauliflower-like growth of blood
vessels covered by a thin layer of epithelial cells.
Secretion of fluid by the choroid plexus depends mainly on active transport of sodium
ions through the epithelial cells lining the outside of the plexus.
The sodium ions in turn pull along large amounts of chloride ions because the positive
charge of the sodium ion attracts the chloride ion's negative charge. The two of these
together increase the quantity of osmotically active sodium chloride in the cerebrospinal
fluid, which then causes almost immediate osmosis of water through the membrane,
thus providing the fluid secretion.

17. MECHANISM OF
FORMATION
Less important transport processes move small amount of glucose into the
cerebrospinal fluid and both potassium and bicarbonate ions out of the cerebrospinal
fluid into the capillaries.
The resulting characteristics of the CSF are:
Osmotic pressure approximately equal to that of plasma sodium ion concentration
Approximately equal to that of plasma chloride ion
About 15 per cent greater than in plasma potassium ion approximately 40 per cent less
glucose

19. ABSORPTION OF CSF THROUGH ARACHNOID VILLI
The arachnoidal villi are fingerlike inward projections of the arachnoidal membrane through
the walls into venous sinuses.
villi form arachnoidal granulations can protruding into the sinuses.
The endothelial cells covering the villi have vesicular passages directly through the bodies of
the cells large enough to allow relatively free flow of (1) cerebrospinal fluid, (2) dissolved
protein molecules, and (3) even particles as large as red and white blood cells into the venous
blood.

20. CEREBROSPINAL FLUID
CIRCULATION

22. THE FUNCTIONS OF THE CEREBROSPINAL
FLUID
1. Cushions and protects the central nervous system from
trauma
2. Provides mechanical buoyancy and support for the brain
3.Serves as a reservoir and assists in the regulation of the
contents of the skull
4. Nourishes the central nervous system
5. Removes metabolites from the central nervous system
6.Serves as a pathway for pineal secretions to reach the
pituitary gland

23. CLINICAL
APPLICATIONS
HYDROCEPHALUS
•Hydrocephalus refers to an abnormal accumulation of
CSF in the cranium.
Causes of hydrocephalus include:
• Obstruction to CSF circulation,
• Excessive production of CSF and
• Interference with absorption of CSF.

24. TYPES OF HYDROCEPHALUS
1. Internal or non-communicating hydrocephalus
occurs when obstruction is within the ventricular
system
2.External or communicating hydrocephalus occurs
when obstruction is in subarachnoid space or arachnoid
villi.

25. Lumbar and cisternal puncture
•Lumbar puncture refers to the tapping of CSF from
the lumbar cistern.
•It is performed by inserting a Needle in between the
L2 and L3 or L3 and L4 vertebrae into the
subarachnoid space within vertebral canal,
•as there is No risk of damage to spinal cord as it ends
at the level of first Lumbar vertebra.

26. Cisternal puncture refers to the tapping of CSF from
the Cisterna magna.
•To do this, a needle is passed through the Posterior
atlanto-occipital membrane forwards and upwards
•To a depth of 4.5 cm from the surface.

27. USES OF LUMBAR PUNCTURE
Lumbar puncture is used for:
1. Collecting CSF for diagnostic purposes
2.Injecting drugs (intrathecal injection) for spinal
Anesthesia, analgesia and chemotherapy
3. Measuring the pressure exerted by CSF.

28. THANK YOU . . .