Cerebrum Flashcards
Cerebrum
•Largest Part of Brain.
•Also known as Pallium.
•SA=2000cm²
•Occupies - Ant, Middle cranial Fossa
& Supratentorial Part of post. Cranial Fossa.
•Made up of
Outer- grey matter
Inner-white matter.
(some neuronal masses Called basal ganglia nuclei within white matter).
- separated by - Median Longitudinal fissure.
- connected to each
corpus callosum.
• 2 cerebral hemispheres present
contains
• diencephalon.
- lateral ventricle.(CSF)
- Flow of info. b/w them throu
commissural fibres. - b/w various parts Association fibres.
- B/w upper/lower parts projection fibres.
Cerebral sulci and gyri
Cerebral cortex is folded into gyri (Greek circle) which are separated from each other by sulci
. This pattern increases the surface area of the cortex.
Types of sulci
According to FUNCTION
1 Limiting sulcus
- separates at its floor two areas which are different functionally and structurally.
- For example, the central sulcus between the motor and sensory areas
2 Axial sulcus
- develops in the long axis of a rapidly growing homogeneous area
- For example, thepostcalcarine sulcus in the long axis of the striate
area
3 Operculated sulcus
- separated by its lips in two areas, and contains a third area in the walls of the sulcus,
- e.g. the lunate sulcus (Fig. 8.6c).
According to FORMATION
1 Primary sulci
- formed before birth, independently. - Example is central sulcus.
2 Secondary sulcus is produced by factors other than the exuberant growth in the adjoining areas of the cortex.
- Examples are the lateral and parieto-occipital sulci.
According to DEPTH
1 Complete sulcus
- is very deep so as to cause elevation in the walls of the lateral ventricle. - Examples are the collateral and calcarine sulci.
2 Incomplete sulci
- are superficially situated and are not very deep,
- e.g. precentral sulcus
Cerebral hemispheres
External features
CEREBRAL HEMISPHERE
External Features
Each hemisphere has the following features. (3 surfaces, 4 borders , 3 poles)
Three Surfaces
Superolateral surface: The superolateral surface is convex and is related to the cranial vault
Medial surface:
The medial surface is flat and vertical. It is separated from the corresponding surface of the opposite hemisphere by the falx cerebri and the
longitudinal fissure
Inferior surface: The inferior surface is irregular. It is divided
into an
anterior part the orbital surface, and a posterior part the tentorial surface. The two parts are separated by a deep cleft called the stem of the lateral sulcus
Four Borders
Superomedial border:
- It separates the superolateral surface from the medial surface
**Inferolayeral surface:””
- separated the superolateral from inferior surface
- anterior part - superciliary border
- depression 5cm in front of occipital pole - preoccipital notch
Medial orbital border:
Sep (medial, orbital)
Medial occipital border:
(Medial and tentorial surface)
3 poles
1. Frontal (ant)
2. Occipital (post)
3. Temporal (ant of temporal lobe)
INSULA
Insula lies deep in the lateral fissure
Surrounded by circular sulcus
Overlapped by adjacent cortical area - opercula
Insula comprises frontal operculum
( between anterior and ascending rami of lateral sulcus.)
Parietal operculum
lies between (ascending and posterior rami of lateral sulcus.)
The temporal opercula
( below posterior ramus of lateral sulcus formed by superior temporal gyri.)
Insula is a pyramidal area,
apex near anterior perforated substance.
Three zones are seen here-
afferents reach from
ventral posterior nucleus of the thalamus, medial geniculate body and part of pulvinar.
Efferents reach to areas 5, 7, olfactory, limbic system and amygdala.
Role of anterior insular cortex is in olfaction and taste.
Role of posterior insular cortex is in language function
Sulci and gyri of
1. Superolateral surface
Sulci
- precentral
- Superior frontal
- Inferior frontal
Gyri
- precentral
- superior frontal
- middle frontal
- inferior frontal
(Anterior horizontal
Anterior ascending of lateral sulcus
Pars orbitals
Pars triangularis
Pars opercularis)
Sulci and gyri of
Parietal lobe
Postcentral
Intraparietal
Gyrus
Postcentral
Superior parietal lobule
Inferior parietal lobule
(Ant- supramarginal
Mid- angular
Post- upturned end of inferior temporal sulcus)
Temporal lobe (sucl and gyri)
Temporal lobe
Sulci
A. Superior temporal
B. Inferior temporal
Gyri
a. Superior temporal
b. Middle temporal
c. Inferior temporal
Occipital lobe sucl and gyri
- Occipital lobe
Sulci
A. Transverse occipital
B. Lateral occipital
C. Lunate
D. Superior and inferior polar
E. Calcarine
Gyri
a. Arcus parieto-occipitalis
b. Superior occipital
c. Inferior occipital
d. Gyrus descenden
a
Medial surface sulci and gyri
sulci
A. Anterior parolfactory
B. Posterior parolfactory
C. Cingulate
D. Callosal
G. Calcarine
E Suprasplenial or subparietal
F. Parieto-occipital
Gyri
a. Paraterminal
b. Paraolfactory (subcallosal area)
c. Medial frontal
d. Paracentral lobule
e. Cingulate
F. Cuneus
G. Precuneus
Inferior surface
Sulci
- Olfactory
- Occipitotemporal
- H shaped orbital sulci
- Collateral
- Rhinal
Gyri
a. Gyrus rectus
b. Anterior orbital
c. Posterior orbital
d. Medial orbital
e. Lateral orbital
f. Lingual
g. Uncus
h. Parahippocampal
- Medial occipitotemporal
J. Lateral occipitotemporal
