Dr. Ahmed Fathalla Ibrahim

TYPES OF FIBRESASSOCIATION FIBRES:• They connect cortical areas lying within

same cerebral hemisphereCOMMISSURAL FIBRES:• They cross midline & connect cortical areas

in one hemisphere to functionally related cortical areas in the other hemisphere

PROJECTION FIBRES:• They connect cortical areas to areas

outside cerebral hemispheres

ASSOCIATION FIBRES

SHORT:

• They connect adjacent gyri in same lobe

LONG:

• They travel through white matter & connect gyri of different lobes

ASSOCIATION FIBRES

LONG ASSOCIATION FIBRES

• Superior longitudinal fasciculusSuperior longitudinal fasciculus::1. Connects frontal and occipital

lobes2. A part connects frontal and

temporal lobes in dominant hemisphere (arcuate fasciculus): links Broca’s and Wernicke’s areas (areas important for language function)

LONG ASSOCIATION FIBRES• Inferior Longitudinal fasciculusInferior Longitudinal fasciculus:: 1.Runs from occipital to temporal poles2.Connects primary visual & visual

association areas3.Contributes to function of visual

recognition4.Lesion: object agnosia (cannot

recognize objects), prosopagnosia (cannot recognize faces)

LONG ASSOCIATION FIBRES

• Uncinate fasciculusUncinate fasciculus::

1. Connects frontal and temporal lobes

2. Connects parts involved in regulation of behavior

• CingulumCingulum::

1. Travels along frontal, parietal and temporal lobes

2. Connects parts of limbic lobe

COMMISSURAL FIBRES

• Corpus callosum:Corpus callosum:

1. The largest of commissural fibres

2. Connects corresponding regions of frontal, parietal & occipital lobes in both hemispheres (but not temporal)

CORPUS CALLOSUM

SpleniumBody

Genu

Rostrum

COMMISSURAL FIBRES

• Major parts of Corpus callosum:Major parts of Corpus callosum:1. Rostrum: connects the inferior

surfaces of frontal lobes2. Genu: fibres curve forwards to form

anterior forceps (forceps minor) that connect frontal lobes

3. Body: most of fibres run transversally & connect parietal lobes

4. Splenium: fibres curve backwards to form posterior forceps (forceps major) that connect occipital lobes

COMMISSURAL FIBRES

• Anterior commissure:Anterior commissure:

1. Formed of a small & a large bundle

2. The small bundle connects olfactory regions in temporal lobes

3. The large bundle connects the rest of temporal lobes

• Hippocampal commissure:Hippocampal commissure:

• They connect the fornix on each side

PROJECTION FIBRES

• They are ascending & descending fibers

• Fibres projecting to & from cerebral cortex are distributed radially as corona radiatacorona radiata

• Fibres become concentrated to form the internal capsulethe internal capsule

INTERNAL CAPSULE

INTERNAL CAPSULE

• It is a V-shaped band of projection fibres

• It is divided into:

1. Anterior limb

2. Genu

3. Posterior limb

4. Retrolenticular part

INTERNAL CAPSULEAnterior limb:Anterior limb:• Site: between head of caudate

nucleus & lentiform nucleus• Contents: 1. Fibres from anterior nuclear group of

thalamus to cingulate gyrus2. Fibres from medial nuclear group of

thalamus to prefrontal cortex3. Frontopontine fibres

INTERNAL CAPSULE

Genu:Genu:

• Site: between head of caudate nucleus & thalamus

• Contents:

1. Corticobulbar fibres

INTERNAL CAPSULE

Posterior limb: Posterior limb: • Site: between thalamus & lentiform

nucleus• Contents:1. Corticospinal fibres2. Fibres from ventral posterior nucleus

of thalamus to postcentral gyrus3. Fibres from ventral anterior & ventral

lateral nuclei of thalamus to motor regions of frontal lobes

INTERNAL CAPSULE

Retrolenticular part:Retrolenticular part:• Site: behind lentiform nucleus• Contents:1. Fibers from medial geniculate body

of thalamus to auditory cortex2. Fibers from lateral geniculate body

of thalamus to visual cortex3. Parieto- temporo- &

occipitopontine fibres

LATERAL VENTRICLE

1. Anterior horn of LV

2. Body of LV

3. Posterior horn of LV

4. Inferior horn of LV

5. Interventricular foramen

6. Third Ventricle

7. Supraoptic recess of TV

8. Infundibular recess of TV

9. Suprapineal recess of TV

10. Cerebral acqueduct

11. Fourth Ventricle

12. Lateral recess of FV

VENTRICULAR SYSTEM OF BRAIN

LATERAL VENTRICLE

• CAVITY: of telencephalon

• SITE: within cerebral hemisphere

• SHAPE: C-shaped

• COMMUNICATION: with 3rd ventricle through the interventricular foramen of Monro

• HORIZONTAL SECTION III:1- Genu of corpus callosum.2- Forceps minor.3- Anterior horn of lateral ventricle.4- Head of caudate nucleus.5- Thalamus.6- Septum pellucidum.7- Body of fornix.8- Posterior horn of lateral ventricle.9- Splenium of corpus callosum.10- Forceps major.11- Optic radiation.12- Lateral sulcus.13- Tail of caudate nucleus.14- Putamen. 15- Claustrum.16- Anterior limb of internal capsule.17- Genu of internal capsule.18- Posterior limb of internal capsule.

Tail of caudate N

Hippocampus

Inferior horn of LV

PARTS OF LATERAL VENTRICLE

• ANTERIOR HORN:ANTERIOR HORN:1. Cavity of frontal lobe

2. Lies in front of interventricular foramen

3. Its anterior wall: genu of corpus callosum

4. Its floor: rostrum of corpus callosu

5. Its roof: body of corpus callosum

6. Its lateral wall: head of caudate nucleus

7. Its medial wall: septum pellucidum

PARTS OF LATERAL VENTRICLE

• BODY:BODY:1. Cavity of parietal lobe2. Lies behind interventricular foramen3. Its floor: thalamus & fornix4. Its roof: body of corpus callosum5. Its lateral wall: body of caudate

nucleus6. Its medial wall: septum pellucidum

PARTS OF LATERAL VENTRICLE

• POSTERIOR HORN:POSTERIOR HORN:1. Cavity of occipital lobe2. Its medial wall: splenium of corpus

callosum• INFERIOR HORNINFERIOR HORN1. Cavity of temporal lobe2. Its roof: tail of caudate nucleus3. Its floor: hippocampus