4. • The brain ventricles are four cavities located
within the brain that contain cerebral spinal
fluid (CSF).
• There are two lateral ventricles—one on each
side of the cerebral cortex.
• Third ventricle, which is lower in the brain.
• Fourth ventricle, which runs along the
brainstem.
5.
6.
7. • Choroid plexuses are numerous villi located in
the walls of the lateral ventricles,roofs of the
third and fourth ventricles which secretes the
cerebrospinal fluid.
• Structurally, each villus consists of three
components;
– A layer of modified ependymal cells (choroid
cells), which faces the lumen of the ventricles and
secretes the CSF.
– A layer of pia mater (tela choroidea)
– A fenestrated capillary directly beneath the pia
mater.
8. • Blood-brain barrier (BBB)
• The layers of choroid plexus form a selectively
permeable barrier called the blood-brain barrier
(BBB).
• Function- to control the movement of water and
solutes into the CSF, as well as from the CSF into
the neural tissue.
9.
10. • Total volume of CSF-150-270 mL, this means that
the entire volume of CSF is replaced around 4 times
per day.
• Circulation
• The CSF passes from the lateral ventricles to the
third ventricle through the interventricular foramen
(of Monro).
• From the third ventricle, the CSF flows through the
cerebral aqueduct (of Sylvius) to the fourth
ventricle.
11. • From the fourth ventricle, some CSF flows through a
narrow passage called the obex and enters the
central canal of the spinal cord.
• However, the majority of CSF passes through the
foramen of Magendie and two lateral foramen of
Luschka to subarachnoid space.
• It is finally reabsorbed into the dural venous sinuses
through arachnoid granulations.
12. Absorption
• There are three recognized routes through which
CSF exits the subarachnoid space (SAS) to enter the
cerebral venous system;
– arachnoid granulations,
– minute channels that pass through the cribriform plate
of ethmoid bone, and
– the lymphatic system.
13. Arachnoid granulations
• The arachnoid granulations are the protrusions of
the arachnoid mater that pierce the dura mater
and protrude into the dural venous sinuses.
• Normally the pressure of the CSF is higher than
that of the venous system, so CSF flows through
the villi and granulations into the venous blood.
14. Minute channels in the
cribriform plate
• From the subarachnoid
space through openings
in the cribriform plate of
the ethmoid bone.
• These channels traverse
the cribriform plate
together with the fila
olfactoria of the
olfactory nerve (CN I)
and drain into the
lymphatic channels of
the nasal mucosa.
15. Functions of CSF:
• protective and metabolic functions.
• acts as a shock absorber thus protecting the brain
from injury.
• It provides neutral buoyancy that prevents the brain
from compressing the blood vessels and cranial
nerves
• It removes by-products of metabolism and plays an
important role in the homeostasis and metabolism of
the central nervous system.
17. • Hydrocephalus
– Hydro- water
– Cephalus- Head
Hydrocephalus is caused by
1. increased production of CSF (hypersecretory
hydrocephalus),
2. an obstruction of its flow (non-communicating
or obstructive hydrocephalus),
3. or by impaired absorption through the
arachnoid villi (malabsorptive hydrocephalus).
18.
19. Clinical feature
1. Increased intra cranial pressure
2. Hydrocephalus is followed by an abnormal
enlargement of the head in children due to an
abnormal increase in the amount of CSF.
3. This creates increased pressure within the
cranium leading to a degeneration of brain
4. Papilloedema
5. Projectile vomiting
20. • Sleep can be divided into two different general
phases:
1. REM sleep and
2. non-REM (NREM) sleep.
Brain waves during REM sleep appear very similar
to brain waves during wakefulness.
In contrast, non-REM (NREM) sleep is subdivided
into four stages distinguished by characteristic
patterns of brain waves.
21. Stage 1
• transitional phase that occurs between wakefulness
and sleep
• During this time, there is a slowdown in both the
rates of respiration and heartbeat.
• Alpha (8-13Hz) and theta(4-7Hz) waves.
22. stage 2 sleep
• the body goes into a state of deep relaxation.
• Theta waves still dominate the activity of the
brain, but they are interrupted by brief bursts
of activity known as sleep spindles and K
complexes.
23. Stage 3 and stage 4
• often referred to as deep sleep or slow-wave
sleep because these stages are characterized by
low frequency wave (0.5-4 Hz)
• Heart rate and respiration slow dramatically.
• Much more difficult to awaken someone from
sleep.
24.
25. REM sleep
1. REM sleep is marked by rapid movements of the
eyes
2. brain waves are similar to when a person is
awake
3. paralysis of muscle systems (no voluntary
movement)
4. dreaming occurs
5. Increased activity in occipital lobe
