The document discusses cerebrospinal fluid (CSF), including its location within the brain ventricles and surrounding structures, composition, functions like cushioning the brain and regulating cranial pressure, and formation primarily by the choroid plexus. It describes CSF circulation through the ventricles and absorption into venous blood, and how CSF pressure is regulated. Diseases related to CSF and cerebral blood flow are examined, such as stroke, brain injury, edema, and increased CSF pressure. The protective mechanisms of the brain like autoregulation of blood flow are outlined. The blood-brain and blood-CSF barriers that protect the brain are also summarized, along with aspects of brain metabolism.

1. CEREBROSPINAL FLUID (C.S.F)
By :
Dr Uffaq Zeb (PT)
DPT (RMI-KMU)
MSNMPT* (RIU)
1

2. CSF
OBJECTIVES
 Physiological Anatomy
 Location
 Composition
 Functions
 Formation
 Circulation
 Reabsorption
 CSF Pressure
 Diseases
 Cerebral blood flow
 Perivascular Space
 Lymphatic system
 Cerebral Vascular
Resistance
 Cerebral
Microcirculation
 Protective mechanisms
of brain
 Blood-CSF and
Blood- Brain Barriers
 Brain metabolism
2

3. CSF
C.S.F LOCATION
 Ventricles of brain
 Cisterns around outside of brain
 Subarachnoid around
 Brain
 Spinal cord
 All these chambers are connected with one
another
 Constant pressure
3

4. CSF
VENTRICLES OF BRAIN
(RIGHT LATERAL ASPECT)
4

5. CSF
VENTRICLES OF BRAIN
(ANTERIOR ASPECT)
5

6. CSF
6
Ventricles
of
Brain
(Superior
Lateral
aspect)

7. CSF
CHARACTERISTICS OF CSF
1. Clear, colorless,
transparent
2. Reaction: Alkaline
3. 500 – 700 ml/day (0.2
ml/min)
4. Total 100 – 160 ml
7

8. CSF
COMPOSITION OF CSF
 Water: 99.13%
 Solids: 0.87 %
 Organic
 Inorganic
 Cells
8

9. CSF
COMPOSITION OF CSF
1. GLUCOSE is 30% less (64mg%)
2. Protein. Only 20-25mg% as compared to
7500mg% in plasma
3. Cells. Very few lymphocytes (1-5 cell/mm3)
4. osmotic pressure equal to plasma;
5. sodium ion equal to plasma;
6. chloride ion 15 percent greater than
plasma;
7. potassium ion 40 per cent less;
9

10. CSF
FUNCTIONS OF C.S.F
1. Acts as fluid buffer (cushioning the CNS
against injury)
2. Acts as reservoir to regulate the
contents of the cranium
3. May act as a medium of nutrient
exchange in the CNS; However brain
carries out its metabolic exchanges
directly with blood.
4. Clinical - DIAGNOSTIC
Therapeutic 10

11. CSF
FORMATION OF CSF
Sites:
>2/3 by Choroid plexus
<1/3 by Ependymal surfaces
arachnoidal membrane
perivascular spaces
(A small amount also comes from brain
itself)
Choroid plexus: Cauliflower like growth
of blood vessels covered by thin
epithelium, projecting into all
ventricles
11

12. CSF
CHOROID
PLEXUS IN A
LATERAL
VENTRICLE
12

13. 13
Flow of CSF
1
2
3
4
5
6
7
8

14. 14
Flow of CSF
1
2
3
4
5
6

15. CSF
PATHWAY OF CSF
15

16. CSF
CIRCULATION OF C.S.F
16
Lateral Ventricles
Monro
3rd Ventricle
Aqueduct of
Sylvius
(Mesencephalic Aqueduct)
4th Ventricle
Subarachnoid
Space
2 – Luschka (lat.)
1 – Magendie

17. CSF
17
Flow of
CSF

18. CSF
18

19. CSF
ABSORPTION
 To the venous system by bulk fluid through
arachnoid granulations, located in the
superior sagital sinus by pressure
gradient.
 (Arachnoid villi function like Valves and allow
one-way flow)
 Arachnoid granulations :
 Projections of arachnoidal membrane in
venous sinuses:- Arachnoid villi (Microscopic)
 Collection of Arachnoid villi:- Arachnoidal
Granulations (Macroscopic)
 Endothelial cells cover the villi
19

20. CSF
DRAINAGE OF A PERIVASCULAR SPACE
INTO THE SUBARACHNOID SPACE
20
Lymphatic system

21. CSF
REGULATION OF CSF PRESSURE
 Balance between
 Formation
and
 Reabsorption
21

22. 22
Cerebral Blood Flow
(CBF)

23. CSF
CEREBRAL BLOOD FLOW (CBF)
 15% of Cardiac Output
 750-900 ml/min
23

24. CSF
AUTOREGULATION OF CBF
 Definition of Autoregulation:
 The process by which blood flow to the tissues is
maintained at relatively constant level despite
changes in perfusion pressure
 Extremely well autoregulated between arterial
pressure limits of 60 and 140 mmHg
 In hypertensives, upto 160-180 mmHg
 Roll of Sympathetic Nervous System in exercise
 Very high mean arterial pressure
 Sympathetic stimulation causes vasoconstriction of brain
arteries to prevent vascular hemorrhage
24

25. CSF
AUTOREGULATION OF CBF
25

26. CSF
CEREBRAL MICROCIRCULATION
 Capillaries are much less “leaky”
 No fenestrations (few exceptions)
 Mechanism: Glial feet by the surrounding
Glial cells surround the capillaries
26

27. CSF
PROTECTIVE MECHANISMS OF
BRAIN
1. Trauma
 Skull bones
 CSF
2. Blood flow in case of high arterial
pressure
 Autoregulation
 Sympathetic nervous system e.g. in
exercise
 Walls of small arterioles become
thickened to prevent transmission of
high blood pressure to capillaries
27
Contd…..

28. CSF
PROTECTIVE MECHANISMS OF
BRAIN
3. Blood flow in case of low blood
pressure and metabolic disorders
 Autoregulation
 Roll of CO2, H+ and O2
4. Edema
 Tight capillary junctions
5. Protection of brain from endogenous
and exogenous toxins
 Blood-CSF and Blood- Brain Barriers
28

29. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
 Cerebral stroke
 Brain injury
 Brain edema
 ↑CSF Pressure
29

30. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(CEREBRAL STROKE)
Blockage of cerebral arteries
Rupture of cerebral arteries
30
Contd……..

31. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(CEREBRAL STROKE)
BLOCKAGE OF CEREBRAL ARTERIES
Old age
Arteriosclerotic plaques
Activation of clotting mechanism
31
Contd……..

32. CSF
DISEASES RELATED TO CSF AND CEREBRAL BLOOD
FLOW
(CEREBRAL STROKE)
RUPTURE OF CEREBRAL ARTERIES
 Rupture of cerebral arteries
 High blood pressure
 Middle cerebral artery
 Loss of function in Wernich’s speech comprehension area
 Dementia
 Loss of function in Broca’s area
 Unable to speak
 Posterior cerebral artery
 Infarction in occipital lobe
 Loss of vision on both sides in the half of retina on the same side of
stroke lesion
 Damage to blood supply of midbrain
 Blockage of nerve conduction in major pathways between brain
and spinal cord
 Sensory and motor abnormalities
32

33. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(BRAIN EDEMA)
 When systems for protecting against
transudation of fluid into the brain break down
e.g.
 Brain concussion
 Blow to head
 High blood pressure
 Mechanism
 ↑Capillary Pressure
 ↑ Damage to capillary walls
 Coma and death 33

34. CSF
TREATMENT OF BRAIN EDEMA
 Emergency
 Osmotic diuretics
 Mannitol
 Ventricular needle puncture
34

35. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(BRAIN INJURY)
 Coupe
 Damage/injury to the brain on the same side of
trauma
 Countercoup
 Damage/injury to the brain on the opposite side
of trauma
37

36. CSF
DISEASES RELATED TO CSF AND CEREBRAL BLOOD
FLOW
(↑CSF PRESSURE)
 Causes
↑ formation (rare)
↑ number of blood cells or plasma proteins
 Hemorrhage
 Infection
 Blockage of reabsorption
↓reabsorption (Obstruction to outflow)
Fibrosis of villi
Brain tumors
Congenital
 Hydrocephalus 38

37. CSF
EFFECTS OF ↑CSF PRESSURE
1. Papilledema
2. Hydrocephalus
39

38. CSF
FECTS OF ↑CSF PRESSURE
 Papilledema : Edema of the Optic Disc
(& Retinal edema)
 Significance of Papilledema
 Clinical diagnosis of ↑CSF Pressure by
ophthalmoscope
 Effects of Papilledema
 Blindness/ blurred vision
40

39. CSF
EFFECTS OF ↑CSF PRESSURE
 Hydrocephalus
 Excess water in cranial vault
 Types
 Communicating
 Non-Communicating
 Swelling of head in children
 Brain damage
41

40. CSF
MEASUREMENT OF CSF PRESSURE
 Person lying horizontally on his/ her side so
that pressure in spinal canal = pressure in
cranial vault
 Spinal needle is inserted in lumber spinal
canal
 Same procedure for composition of CSF
42

41. CSF
BLOOD-CSF AND
BLOOD- BRAIN BARRIERS
 Blood- Brain Barrier
 Tight junctions between adjacent Endothelial cells
 Blood-CSF Barrier
 Tight junctions between adjacent Choroid Epithelial
cells
 Many large molecular weight substances hardly
pass into CSF or interstitial fluids of brain
 These barriers are similar, therefore
 Blood-CSF and Blood- Brain
Barriers= Blood- Brain Barrier
43

42. CSF
FUNCTIONS OF BLOOD- BRAIN
BARRIER
1. Maintain constant environment of neurons
• Brain neurons highly sensitive to changes in
ionic concentration
2. Protection of brain from endogenous and
exogenous toxins
3. Prevention of escape of neurotransmitters
into general circulation
44

43. CSF
CLINICAL IMPLICATIONS OF
BLOOD- BRAIN BARRIER
1. Immature at birth → Kernicterus (Entry of free
bilirubin in brain)
2. Some amines (e.g. dopamine and serotonin do not
penetrate brain tissue, so their precursors are
given, i.e. L-Dopa and 5-Hydroxytryptophane)
3. Breakdown of Blood- Brain Barrier in infection or
injury
45

44. CSF
BRAIN METABOLISM
 Brain weight= 2% of body weight
 Brain metabolism= 15% of body metabolism
(resting, awake)
46

45. CSF
SPECIAL REQUIREMENTS OF BRAIN FOR
OXYGEN
LACK OF SIGNIFICANT ANAEROBIC
METABOLISM
 Most tissues of body can live without
Oxygen for many minutes
 Anaerobic metabolism
 Excessive amounts of glucose and glycogen are
used
 Brain is not capable of significant
anaerobic metabolism
 Reason:-
 High metabolic rate of neurons
 Sudden cessation of brain blood flow/ or
total lack of oxygen:-
 Unconsciousness within 5-10 minutes 47

46. CSF
BRAIN UTILIZES GLUCOSE AS ENERGY
 Brain needs continuous supply of Glucose
 Only about 2 minute supply of glucose
normally stored in brain as Glycogen
 Almost all energy is derived from glucose
derived from blood
 Glucose delivery to brain not dependent
on insulin
 Advantage: preventing loss of function in
Diabetes (↓Insulin)
 Disadvantage: over-treatment with insulin→
unconsciousness 48

47. CSF
SUMMARY
 Physiological
Anatomy
 Location
 Composition
 Functions
 Formation
 Circulation
 Reabsorption
 CSF Pressure
 Diseases
 Cerebral blood flow
 Perivascular Space
 Lymphatic system
 Cerebral Vascular
Resistance
 Cerebral
Microcirculation
 Protective
mechanisms of brain
 Blood-CSF and
Blood- Brain Barriers
 Brain metabolism 49