The Telencephalon
Xiaoming Zhang
The Telencephalon

External features:
 2 Cerebral hemispheres
(separated by longitudinal cerebral fissure)
 Transverse cerebral fissure intervenes between
the hemispheres and cerebellum.
 3 poles, 3 surfaces
3 borders
The Telencephalon

External features:
3 Main fissures on surface of each hemisphere:
 The Lateral sulcus
 The Central sulcus
 The Parietooccipital sulcus
Sulci and gyri of Superolateral
surface
Postcentral gyrus
Postcentral sulcus
Superior parietal lobule
Intraparietal sulcus
Supramarginal
gyrus
Parietooccipital sulcus
5
Lobes:
(divided by 3 sulci)
 The Frontal lobe
 The Parietal lobe
 The Occipital lobe
 The Temporal lobe
 The Insular lobe (insula)
 Main
gyri and sulci
 Dorsolateral surface: in frontal lobe:
— precentral sulcus, superior and inferior frontal sulcus
precentral gyrus
superior frontal gyrus
middle frontal gyrus
inferior frontal gyrus
 in parietal lobe:
— postcentral sulcus
supermarginal gyrus
— intraparietal sulcus
angular gyrus
— postcentral gyrus — superior and inferior parietal
lobule
 in temporal lobe:
superior temporal sulcus
inferior temporal sulcus
superior
middle
inferior temporal gyrus
transverse temporal gyrus
Right superior figure:
Lateral view of cerebral hemisphere
Transverse temporal gyri
Sulci and gyri of Superolateral
surface
Precentral gyrus
Precentral sulcus
Postcentral gyrus
Postcentral sulcus
Superior frontal sulcus
Superior parietal lobule
Inferior frontal sulcus
Superior,
middle
and inferioe
frontal
gyri
Supramarginal
gyrus
Angular gyrus
Superior temporal sulcus
Superior temporal gyrus
Inferior temporal sulcus
Middle temporal gyrus
Inferior temporal gyrus
Sulci and gyri of medial surface
Corpus callosum
Callosal sulcus
cingulate gyrus
Paracentral lobule
Marginal ramus
Parietooccipital sulcus
Cingulate sulcus
Cuneus
Calcarine sulcus
Lingual gyrus
Inferior surface
Olfactory bulb
Olfactory tract
Uncus
Occipitotemporal sulcus
Parahippocampal
gyrus
Medial and lateral
occipitotemporal
gyri
Collateral sulcus
Olfactory trigone
Anterior perforated
substance
Hippocampus
Dentate gyrus
Hippocampal
formation
 Limbic
lobe and limbic system:
 Limbic lobe: composed of cingulate gyrus,
parahippocampal gyrus and uncus.
 Limbic system: comprises of limbic lobe and relative cortex
and other structures of brain (hippocampal
formation, part of amygdaloid nucleus,
hypothalamus and anterior nucleus of
thalamus)
 Internal structures:
 Gray matter
 White matter
 Lateral ventricle
 Gray matter:
 Cortex:
Functional localizations of cerebral cortex
— somatic motor area: in precentral gyrus and anterior part
of paracentral lobule; mainly control skeleton muscles on
the opposite side of body.
— somatic sensory area: in the postcentral gyrus and
posterior part of paracentral lobule; receive the sensory
signals from skin, proprioceptors and taste receptors on
the opposite side of body.
First
somatic
motor
area
Characters
• 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, VA, VL and
VPL, sending out fibers to form
pyramidal tract, controlling
voluntary movements
First somatic sensory area
Characters
• Sensory
representation, like
motor area, is crossed
and inverted
• Receiving and
interpret sensation
from opposite side of
body
— visual area (striate area): surrounds the calcarine sulcus ;
receive the data from the temporal half of ipsilateral
retina and nasal half of the contralateral retina.
— auditory area (acoustic area): in the transverse temporal
gyri; efferent fibers of medial geniculate nucleus of
bilateral side end in this area.
— visceral moter area: in the limbic lobe.
— The language areas:
1. Writing area—posterior part of middle frontal gyrus.
2. Motor speech area— posterior part of inferior frontal gyrus.
3. Auditory language area posterior part superior temporal gyrus
4. Visual language area -angular gyrus
 basal ganglion :
 Corpus striatum:
Caudate nucleus:
“C” – shaped
head, body and tail of caudate nucleus
Lentiform nucleus:
Claustrum:
between the lentiform nucleus and insula.
 Amygdaloid body:
holds the amygdaloid nucleus and lies at the end
of tail of caudate nucleus.
 White matter: 3 kinds of fibers
 Association fibers:
— connect cortical areas in same hemisphere.
— Superior longitudinal fasciculus
— Inferior longitudinal fasciculus
— Cingulum
—Uncinate fasciculus
— Arcuate fibers
 Commissural fibers: — Corpus callosum
* at the bottom of longitudinal cerebral fissure
* 4 parts : rostrum, genu, trunk and splenium
— anterior commissure
— commissure of fornix:
 Projection fibers:
— connect the cortex and subcortical structures
— internal capsule:
* a plate of white matter
* position:
medially to the lentiform nucleus;
laterally to the caudate nucleus and
thalamus.
* “X” – shaped in the horizontal section
* 3 parts: anterior limb; posterior limb and genu.
* projection fibers passing through each part of the
internal capsule:
anterior limb—frontopontine tract;
anterior thalamic radiation
genu—corticonuclear tract
posterior limb—corticospinal tract
thalamocortical tract
parieto-occipito-temporo-pontine tract
optic radiation
auditory radiation
Anterior thalamic radiation
Head of caudate nucleus
Frontopontine tract
Corticonuclear tract
Corticospinal tract
Dorsal thalamus
Central thalamic
radiation
Lentiform nucleus
Corticorubral tract
Parieto-occipitotemporo-pontine tract
Acoustic radiation
Medial geniculate body
Optic radiation
Lateral geniculate body
 Lateral ventricles:
 “C”- shaped cavity in each cerebral hemisphere.
 filled with cerebrospinal fluid
 4 parts:
— anterior horn (in frontal lobe)
— central part (in parietal lobe )
— posterior horn (in occipital lobe)
— inferior horn (in temporal lobe)
 communicated with the third ventricle
through the interventricular foramen.
The Coronary section of the brain
Superior view of lateral ventricle
RMB: 35.00