White Matter, Corpus Callosum

8/3/2019 White Matter, Corpus Callosum

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White matter of the cerebrum


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Fibers of the

white matter

Association fibers Projection fibers Commissural fibers


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First: the association fibers2 types of association fibers are found :

Short fibers :connect adjacentgyri

Long associationfibers


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Long association fibers:1-Uncinate fasciculus:between orbital gyri and

anterior portion of

temporal lobe

2-The cingulum:

Between cingulate gyrus

and hippocampus.

3-The superior

longitudinalfasciculus :between

frontal , temporal andoccipital lobes.


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Long association fibers:

4-the inferior longitudinal

fasciculus: connects

between the occipital and

the temporal lobes.

5-fronto-occipital

fasciculus:between thefrontal and the occipital

lobes.


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Corpus callosum:

It is the greatest commissure.Rostrum: Connects between the orbital surfacesof the frontal lobes on both sides

Genu:Connects the anterior part of the frontal

lobes on both sides. The fibers of the genuradiate forwards towards the frontal polesforming the forceps minor.

Body: Connects between the posterior part ofthe frontal lobe and anterior part of the parietallobe on both sides. These fibers radiate laterallyforming the so called radiation of corpus

callosum.


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Splenium

Connects between the posteriorpart of the parietal lobe,temporal lobe and occipital lobe

on both sides. These fibers passeither:

Lateral to the posterior horn of the

lateral ventricle and are calledtapetum.

Medial to the posterior horn of thelateral ventricle and are called

forceps major.


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Commissural Fibers:1. Anterior commissure:It is present in theupper part of the lamina terminalis. It connects

between the following olfactory structures of both

sides:

a. Olfactory bulb.b. Anterior perforated substance.

c. Pyriform area.

d. Amygdaloid bodies.

2. Posterior commissure:It is present in the stalk

of the pineal body, just above the upper end of the

cerebral aqueduct.

.


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3. Habenular commissure:

It is present in the stalk of the pineal body, just

above the posterior commissure. Its fibers are

derived from the stria habenularis.

4. Hippocampal commissure (or commissure

of the fornix):

this commissure is in the form of transversefibers crossing from one crus of the fornix to

the other crus just behind the body of the

fornix. These fibers connect the hippocampus

with its fellow of the opposite side


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Internal Capsule

Projection fibers


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Definition:

The internal capsule is a V-shapedband ofwhite matter in the brain thatseparates the caudate nucleus andthe thalamus (medially) from thelenticular nucleus(laterally(

The internal capsule contains both

ascending and descending axons ofprojection fibers that connect thecerebral cortex with lower centers
http://en.wikipedia.org/wiki/White_matterhttp://en.wikipedia.org/wiki/Brainhttp://en.wikipedia.org/wiki/Caudate_nucleushttp://en.wikipedia.org/wiki/Thalamushttp://en.wikipedia.org/wiki/Lenticular_nucleushttp://en.wikipedia.org/wiki/Lenticular_nucleushttp://en.wikipedia.org/wiki/Thalamushttp://en.wikipedia.org/wiki/Caudate_nucleushttp://en.wikipedia.org/wiki/Brainhttp://en.wikipedia.org/wiki/White_matter


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caudate

thalamus

lentiform

anterior thalamic radiation:(limbic radiation)

genu

anteriorlimb

poster iorlimb

superior thalamic radiation:(somatosensor y and motorradiati ons)

sublenticular radiation:(auditory radiation)

retrolenticular radiation:(optic radiation)

lateralgeniculate

medialgeniculate

midline

thalamus

caudate

thalamus

lentiform genu

anteriorlimb

posteriorlimb

plane of sectionA

A


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Parts:

1-Anterior limb2-Genu

3-Posrerior limb(thalamo-lenticular

part)4-Retro-lentiform part

5-sub-lentiform part.


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Fibers:

part Descending fibers Ascending fibers

Ant. Limb Fronto-pontine fibers Ant. Thalamic radiation

Genu Cortico-bulbar fibers ___________________

Post. limb 1- cortico-spinal fibers

2- Fronto-pontine fibers

3- corico-rubral fibers

Sup. Thalamic radiation

Retrolentiform

Parieto-pontine&occipito-pontine fibers

Optic radiation+ posteriorthalamic radiation

Sub

lentiformTempro-pontine fibers Auditory radiation+inferior

thalamic radiation


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Blood supply:

Anterior limb:anterior cerebral artery

Genu: internal carotid artery

Posterior limb:middle cerebral artery,ant.Choroidal artery)

Retro&Sub-lenticular parts: anterior choroidalartery
http://en.wikipedia.org/wiki/Anterior_cerebral_arteryhttp://en.wikipedia.org/wiki/Middle_cerebral_arteryhttp://en.wikipedia.org/wiki/Anterior_choroidal_arteryhttp://en.wikipedia.org/wiki/Anterior_choroidal_arteryhttp://en.wikipedia.org/wiki/Anterior_choroidal_arteryhttp://en.wikipedia.org/wiki/Anterior_choroidal_arteryhttp://en.wikipedia.org/wiki/Middle_cerebral_arteryhttp://en.wikipedia.org/wiki/Middle_cerebral_arteryhttp://en.wikipedia.org/wiki/Anterior_cerebral_artery


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Thank you

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White Matter, Corpus Callosum