The Telencephalon SHANDONG UNIVERSITY Liu Zhiyu General Appearance

The Telencephalon SHANDONG UNIVERSITY Liu Zhiyu

General Appearance of Cerebrum n n The telencephalon consists of right and left cerebral hemisphere, partially separated by cerebral longitudinal fissure In the depths of the fissure, the corpus callosum connects the hemispheres across the midline The cerebral transverse fissure intervenes between the hemispheres and the cerebellum Each hemisphere has three surfaces: superolateral, medial and inferior

Main Sulci Three principal sulci n n n Central sulcus Lateral sulcus Parietooccipital sulcus

Lobes of Cerebral Hemisphere Five lobes n n n Frontal lobe Parietal lobe Temporal lobe Occipital lobe Insular lobe o Fr tal Parie tal lo e b o l be n be p m e T l lo a r o Occ lob ipital e

Sulci and gyri of frontal lobe n n n n Precentral sulcus Precentral gyrus Superior frontal sulcus Inferior frontal sulcus Superior frontal gyrus Middle frontal gyrus Inferior frontal gyrus

Sulci and gyri of frontal lobe Precentral gyrus Precentral sulcus Superior frontal sulcus Inferior frontal sulcus Superior, middle and inferioe frontal gyri

Sulci and Gyri of Parietal Lobe n n n n Postcentral sulcus Postcentral gyrus Intraparietal sulcus Superior parietal lobule Inferior parietal lobule Supramarginal gyrus Angular gyrus

Sulci and Gyri of Parietal Lobe Postcentral gyrus Postcentral sulcus Superior parietal lobule Intraparietal sulcus Supramarginal gyrus Angular gyrus

Sulci and Gyri of Temporal Lobe n n n Superior temporal sulcus Inferior temporal sulcus Superior temporal gyrus Middle temporal gyrus Inferior temporal gyrus Transverse temporal gyri

Sulci and Gyri of Temporal Lobe Superior temporal sulcus Superior temporal gyrus Middle temporal gyrus Inferior temporal sulcus

Sulci and Gyri of Temporal Lobe Transverse temporal gyri

Sulci and gyri of Superolateral surface Precentral gyrus Precentral sulcus Superior frontal sulcus Postcentral gyrus Postcentral sulcus Intraparietal sulcus Superior parietal lobule Inferior frontal sulcus Superior, middle and inferior frontal gyri Supramarginal gyrus Angular gyrus Superior temporal sulcus Superior temporal gyrus Middle temporal gyrus Inferior temporal sulcus

Sulci and Gyri of Medial Surface n n n n n Corpus callosum Callosal sulcus Cingulate gyrus Cingulate sulcus Marginal ramus Paracentral lobule Calcarine sulcus Cuneus Lingual gyrus

Sulci and Gyri of Medial Surface Callosal sulcus cingulate gyrus Corpus callosum Paracentral lobule Marginal ramus Cingulate sulcus Parietooccipital sulcus Cuneus Calcarine sulcus Lingual gyrus

Sulci and Gyri of Inferior Surface n n n n Olfactory bulb Olfactory tract Olfactory trigone Anterior perforated substance Collateral sulcus Occipitotemporal sulcus Medial occipitotemporal gyrus Lateral occipitotemporal gyrus Hippocampal sulcus Parahippocampal gyrus Uncus Hippocampus Dentate gyrus

Sulci and Gyri of Inferior Surface Olfactory bulb Olfactory tract Olfactory trigone Uncus Ant. Perforated substance Occipitotemporal sulcus Parahippocampalgyrus Collateral sulcus Lateral occipitotemporal gyrus Medial occipitotemporal gyrus

Sulci and Gyri of Inferior Surface Hippocampus Dentate gyrus Hippocampal formation

Histology of Cerebral Cortex n n n Archicortex (hippocampal formation) Paleocortex (rhinencephalon) Neocortex (most of cerebral cortex) 3 cell layers 6 cell layers

Functional Location of Cerebral Cortex

First Somatic Motor Area Position: Located in precentral gyrus and anterior portion of paracentral lobule

First Somatic Motor Area Characters n n Representation is inverted, but head and face are upright A body part is represented by a cortical area proportional to its use rather than its size Receiving fibers from postcentral gyrus, ventral anterior, ventral lateral and ventral posterior nuclei Sending out fibers to form pyramidal tract, controlling voluntary movements

First Somatic Motor Area

First Somatic Motor Area

First Somatic Sensory Area Position: Lies in postcentral gyrus and posterior portion of paracentral lobule

First Somatic Sensory Area Characters n Sensory representation, like motor area, is crossed and inverted n Receiving fibers from ventral n posterior nucleus Interpret sensation from opposite side of body

First Somatic Sensory Area

Visual Area n n n Lie on either side of calcarine sulcus in medial surface of occipital lobe Visual cortex of one hemisphere receives impression from temporal part of retina of same side and nasal part of opposite side Lesions of visual cortex produce contralateral homonymous visual field defections

Auditory Area n n Located in transverse temporal gyri Receive auditory information from both ears

n n n Vestibular area: located in front of superior temporal gyrus Olfactory area: located near the uncus Taste area: located at frontal operculum

Language Area It is dominant in left hemisphere in right-handed person n Motor speech area q q n Writing area q q n Located in posterior portion of middle frontal gyrus Damage: agraphia Auditory speech area q q n Located in posterior portion of inferior frontal gyrus Damage: motor aphasia Located in posterior portion of superior temporal gyrus Lesion: sensory aphasia Visual speech area q q Located in angular gyrus Lesion: alexia

Lateral Ventricle n Position: located in cerebral hemispheres n Four parts q q Central part: lies in parietal lobe Anterior horn: extends into frontal lobe Posterior horn: extend into occipital lobe Inferior horn: extend into temporal lobe

Lateral Ventricle Transverse MRI scan, at the level of the anterior horn of the lateral ventricle.

Lateral Ventricle n Communication lateral ventricle → interventricular foramen → third ventricle

Basal Nuclei Globus pallidus Putamen n Corpus striatum q q n Lentiform nucleus Caudate nucleus Claustrum Amygdaloid body －paleostriatum Neostriatum

Basal Nuclei Caudate nucleus Putamen Globus pallidus Claustrum

White Matter Association fibers n n n Run between gyri within the same hemisphere Cerebral arcuate fibers Superior longitudinal fasciculi Inferior longitudinal fasciculi Uncinate fasciculus Cingulum

White Matter Commissural fibers n Corpus callosum q q n n Rostrum Genu Trunk Splenium Anterior commissure Fornix and commissure of fornix

White Matter Projection fibers connect cortex with lower part of brain and spinal cord and they include both ascending and descending fibers ★Internal capsule n Position: a thick lamina of white matter lying between caudate nucleus, thalamus and lentiform nucleus

Internal Capsule Caudate nucleus Lentiform nucleus Dorsal thalamus

Internal Capsule Three parts n Anterior limb of internal capsule q q n Genu of internal capsule q q n Lies between caudate nucleus and lentiform nucleus Containing frontopontine tract and anterior thalamic radiation Is angle at which anterior and posterior limbs meet Containing corticonuclear tract Posterior limb of internal capsule q q Lies between thalamus and lentiform nucleus Contain corticospinal tract, corticorubral tract, central thalamic radiation, parieto-occipitotemporo-pontine tract, acoustic radiation and optic radiation

Anterior thalamic radiation Head of caudate nucleus Frontopontine tract Corticonuclear tract Corticospinal tract Dorsal thalamus Central thalamic radiation Medial geniculate body Lateral geniculate body Lentiform nucleus Corticorubral tract Parieto-occipitotemporo-pontine tract Acoustic radiation Optic radiation

Limbic System n Composition q q n Limbic lobe: includes septal area, cingulated gyrus, parahippocampal gyrus, hippocampus, dentate gyrus, temporal pole, anterior part of insular lobe and so on Associated subcortical nuclei: amygdaloid body, septal nuclei, hypothalamus, epithalamus, anterior nucleus group of thalamus, tegmentum of midbrain Function: concerned with visceral activities, olfaction, emotion and memory, so this system is called ‘visceral brain’