the cerebrum i

The cerebrum I

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•The diencephalon

• The diencephalon

• Cerebral

hemispheres

• Internal capsule

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The white matter

•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

The cerebrum

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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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The white matter

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The white matter 3rd ventricle

•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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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

which they lie)

The white matter The main sulci & Gyri

Lateral view of the left cerebral hemisphere

The white matter The main sulci & Gyri

Medial view of the right cerebral hemisphere

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The white matter The structures situated interior to the cerebral hemispheres:

•Lateral ventricles

•Basal nuclei

•White matter & nerve fibers

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The white matter •Basal ganglia

•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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The white matter •White matter of the cerebral 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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The white matter

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The white matter Internal capsule & its nerve fiber arrangement

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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Dr. Pulasthi Senaratna