CEREBRAL
HEMISPHERES
Longitudinal Fissure
The hemispheres are
separated by a deep
groove,
but are connected deep in
the brain by the corpus
callosum
The hemispheres
communicate with each
other through a thick band
of 200-250 million nerve
fibers called the
corpus callosum
(interhemispheric
commissure).
genu trunk
rostrum
splenium
Transvers cerebral
fissure
Tentorium cerebelli
Cerebral hemispheres consist:
- Gray cortex (pallidum)
The outer 2-6 mm is gray matter
- Underlying white matter
-Basal ganglia (nuclei),
a collection of deep
neuronal masses
The cortex contains ridges (gyri) and valleys (sulci).
Major lobes of the brain:
Central sulcus
-Frontal lobe
-Parietal lobe
Parietooccipital
sulcus
-Occipital lobe
- Insular lobe Temporal lobe
- Limbic lobe
Brodmann’s numbered
map of cerebral
hemispheres
Divided the cortex into
52 different areas
Lateral surface:
Major sulci are lateral
and central sulci
Lateral sulcus (Fissure
of Sylvius): Separates
frontal parietal lobes
and temporal lobe
Central sulcus
Central sulcus
(Fissure of Rolando):
Frontal and parietal
lobes
Sylvian fossa
Frontal lobe: higher functions like personality and emotion
Comprises about 1/3 of hemispheric surface
Lies in the anterior cranial fossa
Extends from central sulcus to frontal pole
Central sulcus
Frontal pole
Has 4 principle gyri:
Central sulcus
1- Precentral gyrus
Precentral sulcus
2- Superior frontal gyrus
Superior frontal sulcus
3- Middle frontal gyrus
Inferior frontal sulcus
4- Inferior frontal gyrus
Inferior frontal gyrus
-Orbital part Anterior r.
-Triangular part Ascending r.
-Opercular part
Premotor motor cortex
Frontal eye field
Primary motor area
8
6 4
Prefrontal
cortex 10
=association
area 45 44
11
Broca’s
speech
area
MOTOR
HOMONCULUS
Parietal lobe:
Central sulcus
- Postcentral gyrus
Postcentral sulcus
-Superior parietal lobule
Intraparietal sulcus
- Inferior parietal lobule
Ascending ramus
Inferior parietal lobule
5,7
3,1,2
- Supramarginal gyrus (40)
- Angular gyrus (39)
Superior
temporal
sulcus
Temporal lobe:
It is primarily involved with auditory processing and memory.
- Superior temporal gyrus Superior temporal sulcus
- Middle temporal gyrus Inferior temporal sulcus
- Inferior temporal gyrus
Temporal pole
Transvers temporal gyri
(Heschl’s transvers convolutions)
Extends from superior temporal gyr. towards the centre of the brain in
transvers direction
Auditory in
function
Considered to be
area 42
Occipital lobe: Visual information from the eyes is processed
here.
- Lies on tentorium cerebelli
- Constitutes the caudal pole of the hemisphere
- Has a number of irregular lateral occipital gyri
- Parietooccipital sulcus is the main sulcus of the medial
surface
Parietooccipital
sulcus
Transvers occipital sulcus
Occipital pole
Insular lobe (insula=island):
Invaginated cortical area buried in the depts of the lateral
sulcus
-Limen insulae continuous with
the anterior perforating Circular sulcus
substance
Gyri
breves
Limen
Gyri longus Apex insulae
Opercular regions:
The parietal, temporal and frontal cortical areas which
surround the insula are called temporal, parietal and
frontal opercular regions.
Medial Surface
Interhemispheric
commissure
(corpus callosum)
genu trunk
rostrum
splenium
Central sulcus
- Medial frontal gyrus
Callosal sulcus Hippocampal sulcus
- Cingulate gyrus
Paracentral lobule: ant.
- Cingulate sulcus Marginal sulcus
and post. paracentral
Paracentral sulcus gyri
-Precuneus
- Parietooccipital sulcus
- Cuneus
- Calcarine sulcus Calcar avis
*
Calcarine *
sulcus
A smaller band of nerve fibers called the anterior
and posterior commissure also connect parts of the
cerebral hemispheres.
Limbic Lobe:
Consists the most medial portions of the frontal,
parietal, temporal and occipital lobes where they
surround the corpus callosum
- Cingulate gyrus
- Area subcallosa
- Hippocampal
Dentate
formation
gyrus
Parahippocampal gyrus
The limbic system :
play a role in emotion, memory, and
motivation
Cingulate gyrus Parahippocampal gyrus Uncus
- Istmus of the cingulate gyrus
Collatera
sulcus
Rhinal sulcus
Parahippocampal gyrus
- Anterior paraolfactory sulcus
- Subcallosal gyrus
- Posterior paraolfactory sulcus
- Paraterminal gyrus
- Terminal lamina
Inferior surface: Consist of two parts
1- Large posterior portion
2- Orbital surface of the frontal lobe
Inferior temporal g.
Uncus
Rhinal s.
Lateral occipitotemporal g
Occipitotemporal s.
Parahippocampal g.
Medial occipitotemporal g.
Collateral s.
Cingulate g.
Lingual g. Calcarine s.
Orbital surface:
Olfactory s. Straight g.
Medial olfactory
Orbital sulci stria and gyrus
Lateral olfactory
Orbital gyri stria and gyrus
Anterior perforating
substance
CEREBELLUM
