2. CLASSIFICATION OF THE NERVOUS SYSTEM:
Anatomically, it is divided into:
1. Central nervous system (CNS )
Includes the brain and spinal cord that are not
capable of regeneration, thus are protected by:
Bones (skull & vertebral column)
Three meninges (pia mater, arachnoid mater and
dura mater)
Cerebrospinal fluid (CSF) in the subarachnoid
space.
3.
4. 2. Peripheral nervous system (PNS)
which includes
12 pairs of cranial nerves,
31 pairs of spinal nerves
5. The Neuron = nerve cell
It is the building unit of the nervous system; it
consists of:
1. cell body : containing the nucleus and cell
organelles
2. processes:
Many short dendrites
One long axon . The axons are generally called
nerve fibers.
10. 1)The cerebrum
• Structure:-
1. It’s the largest part of the brain
2. Divided by a deep fissure into two
parts ( Right and left cerebral
hemispheres)
3. These two hemispheres connected by
a mass of white matter known as
corpus callosum
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11. 3)The superficial part is composed of grey
matter forming the cerebral cortex
4)The deeper layers consist of white matter or
nerve fibres .
5) The cerebral cortex shows many gyri and
sulci
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13. • 5 lobes: frontal, parietal, temporal , occipital &
limbic lobe.
• The main cerebral sulci:
• many sulci, are found but only 3 sulci will be
mentioned that determine the main 4 lobes:
• a) The central sulcus: a vertical sulcus separates
the frontal lobe anteriorly from the parietal lobe
posteriorly.
• b) The lateral sulcus: a horizontal sulcus
separates the temporal lobe inferiorly from both
frontal &parietal lobes superiorly.
• c) The parieto-occipital sulcus: limits the occipital
lobe posteriorly from the parietal lobe anteriorly.
14.
15.
16. 2-The diencephalon
• It is part of the cerebrum on the medial aspect
of each hemisphere. It includes:
a) The Thalamus: a large ovoid grey mass of
specific nuclei ,it acts as a gateway for the
cerebral cortex.
b) The Hypothalamus: is the part that lies below
the thalamus
18. 3- The cerebellum
• External features:
• Formed of 2 cerebellar hemispheres, connected by
median vermis. The outer surface of cerebellum is
characterized by the presence of shallow fissures
dividing its outer cortex into small elevations.
• It has an apparent connections with the brain stem
elements via 3 peduncles:
• a) Superior peduncle: connects the mid brain with
cerebellum.
• b) Middle peduncle: connects the pons with
cerebellum.
• c) Inferior peduncle: connects the medulla with
cerebellum.
19.
20. -Is the junctional area between the cerebrum
superiorly, cerebellum posteriorly & spinal cord
inferiorly.
• Its main parts are the mid brain, the pons &
medulla.
4- The brain stem
21. B-THE SPINAL CORD
It represents the lower part of CNS.
Starts at upper border of Cervical 1 vertebra & ends
at Lumbar 1 vertebra in adults & at Lumbar 3 in infants.
It is surrounded by the 3 meningeal sheaths: dura
mater, arachnoid mater & lastly the inner pia mater.
It is cylindrical in shape having 2 enlargements:
a) Cervical one, opposite upper limb.
b) Lumbar one, opposite lower limb.
Ends inferiorly in tapering end called Conus
medullaris, and from its apex extends the filum
terminale, till the back of 1st coccygeal vertebra.
22. • On each lateral aspect the roots of the spinal
nerves are attached.
• There are 31 pairs of spinal nerves (8
cervical, 12 thoracic, 5 lumbar, 5 sacral & one
coccygeal).
• Each spinal nerve exits from the intervertebral
foramen, except the lower lumbar & sacral
nerves that form a collection like the horse’s
tail, the Cauda equina.
23. Beginning of spinal cord at
Upper border of atlas vertebra
Conus medullaris
Lumbar enlargement
Cervical enlargement
End of spinal cord at lower
Border of L1 vertebra
Filum terminale
