meninges and ventricles of the CNS

1. ivyanatomy.com
Chapter 11, Section 1
Meninges and
Ventricles

2. The central nervous system (CNS)
consists of the brain and spinal cord
introduction
A nucleus (sing. nucleus) refers to a group of cell
bodies within the CNS
e.g. dentate nucleus
A tract is a group of axons within the CNS
e.g. corticospinal tract
The peripheral nervous system (PNS)
consists of cranial and spinal nerves
A ganglion is a group of cell bodies within the PNS
e.g. dorsal root ganglion
A nerve is a group of axons, along with their protective
sheaths in the PNS
e.g. sciatic nerve

3. meninges
The meninges is a three-layered membrane that
surrounds the brain and spinal cord.
1.
Dura Mater “tough mother”
• Tough outer layer of meninges
• Dense connective tissue with many blood vessels and nerves
• Forms dural sinuses that drain venous blood from the brain.
2. Arachnoid Mater “spider-web like”
• Subarachnoid space
• Space between arachnoid and pia mater filled with
Cerebral Spinal Fluid (CSF)
3. Pia Mater “gentle mother”
• Thin membrane with many nerves and blood vessels
• Membrane is attached to surface of brain and spinal cord.

4. Figure 11.1 Meninges (a) membranes called meninges enclose the brain and
Figure 11.1 Meninges (a) membranes called meninges enclose the brain and
spinal cord. (b) the meninges include three layers: dura mater, arachnoid
spinal cord. (b) the meninges include three layers: dura mater, arachnoid
mater, and pia mater. Note the dural sinus formed by the dura mater.
mater, and pia mater. Note the dural sinus formed by the dura mater.

5. Figure 11.2 Meninges of the spinal cord.
(a)three layers of the meninges .
(b)a small space (epidural space) fills the space between
the dura mater and the vertebra.

6. VENTRICLES
Interconnected cavities, called ventricles lie within the
cerebral hemispheres and the brainstem.
Ventricles are continuous with the central canal of the
spinal cord and are filled with Cerebrospinal Fluid (CSF).
4 Ventricles:
2 Lateral ventricles
1st ventricle is in left cerebral hemisphere
2nd ventricle is in the right cerebral hemisphere
Lateral ventricles are connected by interventricular foramina.
Third ventricle
Surrounds the diencephalon
Cerebral aqueduct connects 3rd and 4th ventricles
Fourth ventricle
Within brainstem, just anterior to cerebellum

7. Figure 11.3 Ventricles in the brain. (a) anterior view. (b) lateral view.

8. Cerebrospinal Fluid
CSF is secreted by specialized capillaries called Choroid Plexuses
• CSF complete surrounds brain and spinal cord
• Ependymal cells regulate the composition of CSF
• CSF functions as a nutritive and protective fluid.
Figure 10.4 (a) choroid plexuses
in ventricle walls secrete CSF.
The fluid circulates through
ventricles and central canal.

9. Spinal Tap
The spinal cord ends near the 2nd Lumbar vertebra, but the
arachnoid and dura maters continue to the 2nd Sacral vertebra.
Thecal Sac –
space beyond spinal cord filled with CSF.
Spinal taps (lumbar punctures) and spinal
blocks are usually given below the 4th
lumbar vertebra to access the CSF
without puncturing the spinal cord.
End of section 1, chapter 11

10. Spinal Tap
The spinal cord ends near the 2nd Lumbar vertebra, but the
arachnoid and dura maters continue to the 2nd Sacral vertebra.
Thecal Sac –
space beyond spinal cord filled with CSF.
Spinal taps (lumbar punctures) and spinal
blocks are usually given below the 4th
lumbar vertebra to access the CSF
without puncturing the spinal cord.
End of section 1, chapter 11