2. Cerebrum
• Largest part of brain
• Divided into 2 hemispheres
• Controls all conscious thoughts &
intellectual functions
• Processes somatic motor and sensory
information
9. Grey & white matter
• Outside
• Cortex
• Neurons present
• White
• Axons present
10. Main Sulci
• On superolateral surface
• Two prominent sulci are present
• Posterior ramus of the lateral sulcus
• Central sulcus
• On medial surface - near occipital pole
• Parietooccipital sulcus
• Upper end of this sulcus reaches
superomedial border
• Small part of it can be seen on superolateral
surface
11. Lobes
• Frontal lobe
• Anterior to central sulcus and
• Above posterior ramus of lateral sulcus
• Parietal lobe
• Behind central sulcus
• Bounded below by posterior ramus of the
lateral sulcus and by the second
imaginary line and
• Behind by the upper part of the first
imaginary line
12. Lobes
• Occipital lobe
• Area lying behind the first imaginary
line connecting parieto-occipital sulcus
and pre-occipital notch
• Temporal lobe
• Below posterior ramus of the lateral
sulcus and the second imaginary line
• Separated from the occipital lobe by the
lower part of the first imaginary line
13. Sulci and gyri of frontal lobe
• Precentral sulcus
• Superior frontal sulcus
• Inferior frontal sulcus
• Precentral gyrus
• Superior frontal gyrus
• Middle frontal gyrus
• Inferior frontal gyrus
19. Structures in inferior surface
• In centre
• Interpeduncular fossa
• Between 2 cerebral
hemispheres
• Inferior surface of
hemisphere can be
divided into
• Orbital & tentorial
surfaces
20. Interpeduncular fossa
• Lies anterior to midbrain
• Boundaries
• In front by
• Optic chiasma
• Anterolatealrly by
• Right and left optic tracts
• Posterolaterally
• Crus cerebri
• Posteriorly
• Pons
21. Sulci & gyri on orbital surface
• Olfactory sulcus
• Antero posterior sulcus near medial border
• Olfactory bulb & tract
• Gyrus rectus
• Medial to olfactory sulcus
• Orbital sulcus
• H – shaped
• Anterior, posterior, medial & lateral orbital gyri
22. Sulci & gyri on tentorial surface
• Collateral sulcus
• Near medial border
• Posteriorly forms lateral boundary for Lingual gyrus
• Anteriorly forms lateral boundary for parahippocampal gyrus
• Rhinal sulcus
• Separates uncus from medial occipito temporal gyrus
• Occipitotemporal sulcus
• Lateral one
• Divides the remaining gyri into
• Medial & lateral occipito temporal gyri
23. Insula
• Submerged part of cerebral cortex
• Found in depth of lateral sulcus
• Surrounded by circular sulcus
Lentiform nucleus lies deep to it
24. Functional Areas of Cerebral Cortex
• In 1909, Brodmann’s areas
were described based on
cytoarchitecture
• Later they were found to be
functionally significant
• Cytoarchitecture is based on
• Density of different cortical
neurons and thickness of layers
•
• 6 layers are present in cortex
• Molecular –outermost
• Outer granular – stellate & granule cells
• Outer pyramidal – small & medium
• Inner granular – stellate cells
• Inner pyramidal – medium & large
• Polymorphous – Marinoti cells & multipolar
25. Functional areas in frontal lobe
• Primary motor
• Premotor
• Frontal eye field
• Supplementary motor
• Prefrontal
• Broca’s area
26. Functional areas in frontal lobe
• Precentral motor cortex (area 4)
• Infront of central sulcus including anterior
wall of central sulcus
• Anterior part of paracentral lobule
• Has large pyramidal cells of Betz
• Opposite side body is topographically
represented
• In upside down manner (head is lower and leg
is up
• Lower limb and perineum are on medial side
• Controls highly skilled voluntary
movement of opposite half of body
• Voluntary control of micturition &
defecation are in anterior part of
paracentral lobule
27. Functional areas in frontal lobe
• Premotor cortex (area 6)
• Lies infront of motor cortex
• In posterior parts of superior middle and
inferior frontal gyri
• Inferiorly upto lateral sucus
• Superiorly extends into medial surface
• Anterior to paracentral lobule
• Upper part – writing centre
• Lower part & around ascending ramus
of lateral sulcus
• Motor speech area (44 & 45) (Broca’s area)
28. Functional areas in frontal lobe
• Frontal eye field (8)
• Ability of the eyes to work together
• To follow an object
• Lies infront of upper part of premotor
area
• In posterior part of middle frontal gyrus
• Controls conjugate movements of eye
• Prefrontal cortex (9, 10 & 11)
• Essential for thought process
• Examples
• Solving mathematical problems
• Having foresight
• Giving judgments
29. Functional areas in frontal lobe
• Supplementary motor area (24)
• Primary motor area (6) continues on
medial surface
• Function
• Programming sequential motor
movements
• Lesion
• Results loss in coordination in
movements of two limbs
30. Functional areas in parietal lobe
• Primary somatosensory
• Secondary somatosensory
• Gustatory
• Association
31. Functional areas in parietal lobe
• Primary somatosensory area (3, 1 & 2)
• Lies in
• Posterior wall (3) and lip of central sulcus (1)
• Post central gyrus (2)
• Extends into paracentral lobule
• Receives sense of bladder & rectum fullness
• Functions
• Tactile localization between the 2 points discrimination & tactile
discrimination between 2 objects
32. Functional areas in parietal lobe
• Secondary somatosensory
• Lies along
• Upper lip of Posterior ramus of
lateral sulcus
• Functions
• Responds to stroking the skin
by brush or tapping
33. Functional areas in parietal lobe
• Somesthetic association area (5)
• Lies in
• Anterior part of superior parietal lobule
• Function
• Integrates tactile & visual stimuli
• To determine shape & size of an object
34. Functional areas in temporal lobe
• Primary auditory (41 & 42))
• Auditory association (22)
• Visual association
• Limbic
35. Functional areas in temporal lobe
• Primary auditory area (41 & 42)
• Located in
• Transverse temporal gyrus
• In floor of posterior ramus of lateral sulcus &
adjoining superior temporal gyrus
• Function
• Detecting the direction of the sound
36. Functional areas in temporal lobe
• Auditory association area (22)
• Lies around primary auditory area
• In middle of superior temporal gyrus
37. Functional areas in occipital lobe
• Primary visual cortex (17)
• Called as striate cortex
• Lies in
• Lips & walls of
• Posterior part of calcarine sulcus
38. Functional areas in occipital lobe
• Second visual area (18)
• Lies close to primary visual area
• Function
• Understand the written language
