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BY PROF. SAEED ABUEL MAKAREM

WHIT MATTER OF THE CERBRUM. BY PROF. SAEED ABUEL MAKAREM. White matter of Cerebrum. Each cerebral hemisphere consists of : 1- Cerebral cortex: (outer layer of grey matter). 2- White matter : (enormous mass of nerve fibers). 3- Basal ganglia:

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BY PROF. SAEED ABUEL MAKAREM

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  1. WHIT MATTER OF THE CERBRUM BY PROF. SAEED ABUEL MAKAREM

  2. White matter of Cerebrum • Each cerebral hemisphere consists of: • 1- Cerebral cortex: (outer layer of grey matter). • 2- White matter: (enormous mass of nerve fibers). • 3- Basalganglia: (collection of grey matter in the white matter). • 4- Lateral ventricle: The cavity of the hemisphere.

  3. WHITE MATTER OF CEREBRAL HEMISPHERE • There are 3 types: • 1- Association fibers: • Interconnect cortical sites lying within one hemisphere. • They are short or long fibers . • 2- Commissural fibers: • Connecting functionally related gyri on both hemisphere. • 3- Projection fibers: • Connecting the cortex with the lower centers in thalamus brain stem, or spinal cord. • They are ascending or descending.

  4. Association fibers • A- Short association fibers: • Connect nearer gyri on the same hemisphere. • B- Long association fibers: • Connect distant gyri on the same hemisphere. • Example: • 1-Superior longitudinal fasciculus:

  5. Example: 1-Superior longitudinal fasciculus: Connects the frontal & occipital lobes. It lies above the insula. It has a subsidiary bundle known as arcuate fasciculus, which connects the frontal & temporal lobes. It is important for language function Association fibers

  6. Association fibers • 2- Inferior longitudinal fasciculus: • Connects the occipital & temporal poles. • It is contributed in visual recognition. • 3- Uncinate fasciculus: • U-shaped curved around the bottom of the lateral sulcus. • It connects the anterior & inferior parts of the frontal gyrus with the temporal gyri. • It is important for behavioral regulation.

  7. Association fibers • 4- Cingulum: • Begins in the anterior perforated substance in the frontal lobe. • Runs in cingulate gyrus. • Curves inferiorly to run in the Parahippocampal gyrus. • It is a part of the limbic system • It terminates in the Uncus, (smell center).

  8. COMMISSURAL FIBERS • The major commissural fibers are: • 1-Corps callosum. • 2-Anterior commissure. • 3-Hippocampal commissure ( Commissure of the fornix).

  9. CORPUS CALLOSUM • The greatest commissure of brain. • It connects homologous areas of the 2 cereral hemispheres • Formed of 4 parts: Rostrum, genu, body & splenium. • Lies in floor of great longitudinal fissure . • Its inferior surface is attached to fornix by the septum pellucidum.

  10. CORPUS CALLOSUM • Rostrum & genu interconnect the anterior part of the frontal lobe. • The trunk interconnects the posterior part of the frontal & parietal & temporal lobes. • The splenium interconnects the occipital lobes. • The fibers of the rostrum & genu arch forward to form forceps minor. • The fibers of splenium arch backward to form forceps major.

  11. ANTERIOR COMISSURE • Rounded commissure. • Lies behind the lamina terminals. • Runs transversely in front of the anterior column of fornix. • Interconnects the middle & inferior temporal gyri. • Also, it connects the olfactory regions of the 2 hemisphere.

  12. HIPPOCAMPAL COMMISSURE • Composed of transverse fibers . • Interconnects the posterior columns of the fornix.

  13. PROJECTION FIBERS • These are fibers which connect the cortex to other areas in the brain stem & the spinal cord. • Projection fibers are 2 types: • A- Ascending (afferent),or corticopetal: • Conveying fibers to the cortex • 1- Thalamic radiation: connecting different thalamic nuclei with different parts of cortex. • 2- Optic radiation. • 3- Auditory radiation.

  14. PROJECTION FIBERS • B- Descending (Efferent), or corticofugal: • 1. Pyramidal: a. Corticospinal. b. Corticobulbar. • 2. Corticopontine. • 3. Corticoreticular. • 4. Corticorubral

  15. INTERNAL CAPSULE • Thick band of projection fibers, (porta cerebri). • V-shaped with its concavity directed laterally in horizontal section • Its concavity is related to Lentiform nucleus. • It is formed of: • Anterior limb. • Genu. • Posterior limb.

  16. INTERNAL CAPSULE • Anterior limb: • Between head of caudate nucleus & lentiform nucleus. • It contains: • 1-Anterior thalamic radiation: From anterior & mediodorsal thalamic nuclei, to the frontal cortex. • 2-Frontopontine fibers: That project to pontine nuclei, in the basal part of the Pons.

  17. INTERNAL CAPSULE • Genu of internal capsule: • Is the angle of the V which points medially, between head of caudate nucleus and thalamus. • It contains: • 1- Corticonuclear (Corticobulbar). • 2- Anterior part of sensory (superior thalamic) radiation, from ventral anterior & ventral lateral nuclei to motor regions of the frontal lobe.

  18. INTERNAL CAPSULE • Posterior limb: • A-Lenticothalamic part • Lies between thalamus & lentiform nucleus. • Contains: • 1-Corticospinal fibers. • 2-Frontopontine. • 3-Frontorubral. • 4-Great part of sensory (superior thalamic ) radiation, from the ventral posterior nucleus to the primary somatosensory cortex.

  19. INTERNAL CAPSULE • B-Retrolentiular part: • It contains fibers from medial & lateral geniculate nuclei of thalamus, which form the auditory & optic radiation. • Optic radiation passes to visual cortex, around the calcarine sulcus (geniculoalcarine fibers). • Auditory radiation passes to superior temporal gyrus.

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