5. Meninges
Meninges = (singular Meninx)
• The entire NS (brain, spinal cord, cranial and
spinal nerves and peripheral ganglia) is
covered by tough connective issue. The
protective sheaths around the brain and spinal
cord are referred to as the mininges.
6. • It consist of three layers:
1. Dura mater - outer layer
2. Arachnoid membrane – Middle layer
3. Pia mater – Inner layer
7. 1. Dura mater
• Duramater- “Hard mother”
• Outer layer is thick, tough, and flexible but
unstretchable.
8. 2. Arachnoid Membrane
• Middle layer
• Meaning: name from webline appearance of
the arachnoid trabecular that protrude from it
(from the Greek word arachnae-spider;
trabecula means “track”.
• Soft and spongy, lies beneath the dura mater.
9. 3. Pia mater
• Pia mater-pious mother
• It is closesly attached to the brain and spinal
cord and following every surface convolution
• The smaller surface blood vessels of the brain
and spinal cord are contained within this layer.
10. • Subarachnoid space:
– Between the pia mater and the arachnoid
membrane is a gap which is called subaracnoid
space.
– This space filled Cerebro spinal fluid
11. • 1. PNS is covered with two layers of meinges.
• Middle layer (arachnoid membrane) with its
associated pool of CSF covers only the brain
and spinal cord.
• Outside the CNS the outer and inner layers
(dura and Pia mater) fuse and form a sheath
that covers the spinal and cranial nerves and
the peripheral ganglia.
12. The ventricular system and Production
of Cerebrospinal fluid
Brain
• The brain is soft jelly like
• Its weight is 1400g
• Cant replace fresh brain
• Intact brain within a living human is well
protected. It floats I a bath of CSF contained
within the subarachnoid space.
13. • Brain network is reduced to approaximately
80g because of it is completely immersed in
liquid.
• The CSF surrounding the brai and spinal cord
also reduces the schok to the central nervous
system that would be caused by sudden head
movement.
