2. The white matter
The cerebrum
•It’s situated in the anterior & middle
cranial fossae
•Cerebrum is divided into 2 parts
1)Diencephalon : Forms the central core
2)Telencephalon : Forms cerebral
hemispheres
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3. The white matter
Diencephalon
•It’s a midline structure with symmetrical right & left halves
•It can be divided into 4 major parts :
1. Thalamus
2. Subthalamus
3. Epithalamus
4. Hypothalamus
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5. 3rd ventricle
The white matter
•Situated between the 2 thalami
•Communicates anteriorly with the lateral ventricles
through the inter ventricular foramina (Foramen of
Monro)
•Communicates posteriorly with the 4th ventricle
trough the cerebral aqueduct
•It’s walls are lined by ependyma
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6. The white matter
•Cerebral hemispheres (Telencephalon)
•Largest part of the brain
•2 hemispheres are separated by a deep midline fissure : The
longitudinal cerebral fissure
•Corpus callosum connects the hemispheres across the midline
•Tentorium cerebelli separates the cerebral hemispheres from the
cerebellum
•To increase the surface area of the cerebral cortex, each hemisphere
has formed folds (Gyri) & gyri are separated by sulci (Fissures)
•Each hemisphere is divided into 4 lobes : Frontal, parietal,
temporal & occipital (Named according to the cranial bones under
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which they lie)
7. The main sulci & Gyri
The white matter
Lateral view of the
left cerebral
hemisphere
8. The main sulci & Gyri
The white matter
Medial view of the
right cerebral
hemisphere
9. The white matter
The structures situated interior to the cerebral
hemispheres:
•Lateral ventricles
•Basal nuclei
•White matter & nerve fibers
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10. •Basal ganglia
The white matter
•It’s a collection of grey masses in the white matter of
the hemispheres
•There are 3 main parts
1)Corpus striatum : Divided by the internal
capsule into Caudate & Lentiform nucleus
2)Amygdaloid nucleus : Situated in the temporal
lobe
3)Claustrum
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11. •White matter of the cerebral
The white matter
hemispheres
•It’s composed of myelinated nerve fibers
•The nerve fibers are classified into 3 groups
1)Commissural fibers
2)Association fibers
3)Projection fibers
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13. Internal capsule & its nerve fiber arrangement
The white matter
Relationships between internal
capsule, basal ganglia, and
thalamus in horizontal section.
Notice that descending motor
fibers for the face, arm, and leg
(F, A, L) run in front of ascending
sensory fibers
(f, a, l) in the posterior limb of the
internal capsule.
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14. "It will take only 2 sec to say thanks and will take only 10 sec to
write a comment it will be a nice encouragement for us "
Dr. Pulasthi Senaratna
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