details of cerbrum

1. CEREBRUM
AND
BASE OF THE SKULL

2. INTRODUCTION
 The cerebrum is the largest part of the brain with two
hemisphere.The two cerebral hemisphere are linked by
commisural fibres of corpus callosum.
 Each cerebral hemisphere contains externally highly
convulated cortex of grey matter and internal mass of white
matter or medulla.
 Each cerebral hemisphere contains lateral venticle continous
with the third ventricle through interventricular foramen.
 The cerebral hemispheres contains motor and sensory areas
and the limbic system.
 Each cerebral cortex is often divided phylogenetically into old
allocortex,consisting of archicortex and paleocortex and a
newer neocortex.

3. Longitudinal Fissure
Cerebral hemisphere

4. Cortex and medulla

5. Surfaces of cerebral hemisphere
 Each cerebral hemisphere
has three surfaces
• Superolateral surface
• Medial surface
• Inferior surface.
 Inferior surface further
divided into two
vi. Orbital surface
vii.Tentorial surface

6. Surfaces of cerebral hemisphere………contd.
 Superolateral surface
It follows the concavity of the cranial vault
 Medial surface
It is flat and vertical and seperated from its fellow by the great
longitudinal fissure and falx cerebri.
 Inferior surface
Inferior surface or the basal surface is irregular and divided
into orbital and tentorial surface.

7. Superolateral
Medial surface
Surfaces of the brain

8. Inferior surface
Orbital surface
Tentorial surface

9. Borders of cerebral hemisphere
S
uperomedial border
Inferior border

10. O
ccip
italp
o
le
F
ro
n
talp
o
le
T
em
p
o
ralp
o
le
Poles of the brain

11. Lobes of the brain
Four lobes are
present
• Frontal
• Parietal
• Occipital
• Temporal
 Occasionally
insula is
considered as
the fifth lobe

12. Gyrus and sulcuses
 Each cerebral hemisphere
convulation called Gyrus
 The gyruses are separated
by furrows of varying length
called Sulci.
 The convulated structure
increases the cortical
volume to three times what
it would be if the surface is
smooth.
 The area of the cerebral
cortex is 2200cm²
Sulci
(Groove)
Fissure
(Deep groove)
Gyri
shows a complex pattern of (Elevation)

13. Important sulci and gyri
 In the suprolateral surface:
ii. Lateral sulcus
o Deep cleft on the lateral
and inferior surface
o It has a stem which divides
into three
rami:anterior,ascending,p-
osterior.
o The floor of the posterior
ramus is the insula which is
hidden cortex.
Lateral sulcus
Central sulcus

14. Important sulcus and gyrus…….contd.
ii. The central sulcus
o It is the boundary between frontal and parietal lobes
o It starts at the superomedial border, a little behind the
midpoint between frontal and occipital poles.It runs
downards and forwards for about 8-10cm to end little above
the posterior ramus of lateral sulcus.
o It demarcates the motor and sensory area of the cerebral
cortex.
iii. The other known sulcuses are




superior frontal sulcus
Inferior frontal sulcus
Precentral sulcus
Postcentral sulcus

15. Medial surface
 In the medial surface
 The commisural fibres of
the corpus callosum lies in
the depth of longitudinal
fissure
 Parts of corpus callosum
d. Rostrum
e. Genu
f. Trunk or body
g. Splenium
 The anterior part divided
into outer and inner zone
by cingulate sulcus

16. splenium
Genu
Rostrum
Medial surface with corpus
callosum
Body or trunk

17. Cingulatesulcus
Parieto-occipital sulcus
Calcarinesulcus Collateral sulcus
Sulcus in the medial surface

18. Sulcus and gyrus………contd.
The posterior region of the medial surface is traversed by
parieto-occipital and calcarine sulcus.The parieto-
occipital sulcus marks the boundary between parietal
and occipital lobes.
The visual cortex lies above and below the calcarine
sulcus.
 In the inferior cerebral surface
 Olfactory sulcus
 Rhinal sulcus
 Occipitotemporal sulcus
 Collateral sulcus

19. Orbital sulcus
Occipitotemporal sulcus
Collateral sulcus
Rhinal sulcus
Sulcus and important structures on inferior surface of
cerebral hemisphere
Olfactory sulcus

20. Insula
-Present within the lateral sulcus
Between temporal and frontal
Lobe.
-The overlying cortical areas are
called opercula formed from the
parts of frontal,temporal and
parietal lobe
-Functions linked to emotion and
body’s homeostasis
-i.e perception,motor control,self
awarness,congnitive functioning
interpersonal experience
Insula

21. Cerebral cortex
 Cerebral cortex is an intricate blend of nerve cells and
fibres,neuroglia and blood vessels.
 Microscopically the cortex consists of six layers or laminae
lying parallel to the surface.
From outside to inside
IV.Molecular or plexiform layer
V. The external granular layer
VI.External pyramidal lamina
VII.Internal granular layer
VIII.Internal pyramidal cell layer
IX.Multiform or pleiomorphic layer

22. Pyramidal cells

23. Neocortex has 6 layers
designated I, II, III, IV, V, VI
Pyramidal cells
predominate in layers III
and V
Granule cells in layers II and
IV
Pyramidal cells
Granule cells
Cerebral
cortex

24. Pyramidal cells have large apical
dendrite and basal dendrites
Axon projects downward into
subcortical white matter; may have
collaterals
Pyramidal cell is the primary output
neuron
PY R A MIDA L
C E L L

25. Pyramidal cell
Pyramidal cell

26. Broadmann’s areas
 These areas were defined and
numbered by korbinian
broadmann
 The areas are based on the
cortical cytoarchitectonic
organisation of neurons
 Many of the broadmann’s areas
are defined on neurological
function coorelated closely to
diverse cortical functions.
 For example
 Area 1,2,3 – primary
somatosensory area
 Area 4 – Motor area
 Area 41,42 – Auditory area
 Area 44,45 – Broca’s area,etc

27. s
h
o
u
l
d
e
r
legs
toes
ankle
M
otorC
ortex
s
h
o
u
l
d
e
r
foot
toes
g
enitalia
Sensor
y
Cortex
MAPPING OF SENSORY ANDMOTOR
AREAS TOTHE BODY

28. •Primary Motor Cortex (Precentral Gyrus) – Cortical site
involved with controlling movements of the body.
•Broca’s Area – Controls facial neurons, speech, and language
comprehension. Located on Left FrontalLobe.
Broca’s Aphasia – Results in the ability to comprehend speech, but
the decreased motor ability (or inability) to speak and form words.
Orbitofrontal Cortex – Site of Frontal Lobotomies
* Desired Effects:
- Diminished Rage
- Decreased Aggression
- Poor Emotional Responses
* Possible Side Effects:
- Epilepsy
- Poor Emotional Responses
-Perseveration
(Uncontrolled, repetitive
actions, gestures, or words)
Frontal lobes cortical regions
Primary motor cortex
Broca’s area
Orbitofrontal cortex

29. Parietal lobe cortical
areas
Primary Somatosensory Cortex
(Postcentral Gyrus) – Site involved with
processing of tactile and proprioceptive
information.
Associated s o ma to s ens o ry
area(7)
Somatosensory Association Cortex -
Assists with the integration and interpretation of
sensations relative to body position and
orientation in space. May assist with visuo-
motor coordination
Primary Gustatory Cortex – Primary site
involved with the interpretation of the
sensation of Taste.
Primary gustatory
area (40)
Primary somatosensory area
(3, 1, 2)

30. Primary Visual Cortex – This is the
primary area of the brain
responsible for sight -recognition
of size, color, light, motion,
dimensions, etc.
Visual Association Area –
Interprets information acquired
through the primary visual cortex.
O
ccip
ita
llo
b
ea
n
dco
rtica
lreg
io
n
s

31. White matter of cerebrum
 Consists of myelinated nerve
fibres which are categorized
on the basis of their course
and connections
B. Association fibres
• It links different cortical areas
of the same hemisphere
• Two types
v. Short association fibres
 They are entirely intracotical
 Some merely pass from one
wall of the sulcus to other.
viii.Long association fibres
 They are present in bundles
 Example: uncinate
fasciculus,cingulum,superior
longitudinal fasciculus,etc

32. White matter of cerebrum………contd.
A. Commissural(transverse)
fibres
• Commisural fibres cross the
midline,linking
corresponding areas in the
two cerebral hemisphere.
• The largest commissure is
the corpus callosum.Other
commisures are
• Anterior
• Posterior
• Habenular
• Commissure of the fornix.

33. White matter of cerebrum……..contd.
•
A. Projection fibres
Projection fibres connect
cerebral cortex with lower
levels in the brain and
spinal cord.
• Consists of both
coticofugal and
corticopetal fibres
• Corticofugal fibres
converge from all
directions to form corona
radiata.Corona radiata
continous with the
internal capsule.

34. Corpuscallosum
Anterior commissure
Posterior
commissure
C
o
m
m
issu
reso
fb
rain Commissureof fornix
Habenular
commissure

35. CTSCA
NO
FT
H
EB
R
A
I
N

36. CT scan of the
brain showing
a tumour in the
right cerebral
hemisphere
CT scan of brain…….contd

37. M
R
IO
FB
R
A
I
N

38. .A non-progressive
disorder
•Caused by brain injury
pre (70-80%), peri, or
post natally
•Injure occurs before
CNS reaches maturity
•Patients often have great
potential masked by their
connections
CE RE B RA L PA L S Y
Manifestation
• Malfunction of motor centers
•Postural and balance
difficulties
•Normal life expectancy
possible
• Early death respiratory

39. Spastic
• 52-70% of all CPs
• Hyperirritability of muscles
• Arms flexed, legs internally rotated
• Difficulty bending into a sitting position
• Difficulty with head control
• Postural difficulty
• May not have protective extension
Athetoid or Dyskinetic Type
• 25- 30% of CPs
•Uncontrollable writhing movements of
opposing muscle groups
• All four extremities involved
• Neck and face involved
• Voluntary movements are flailing
• Difficulty uprighting and balancing
•Grimacing

40. Other types
• Tremors (rare form) of CP
• Rigid 5 -10% of CPs
• Flaccid (Hypotonicity)
• Mixed 15 - 40% of CPs
• 5 to 10 %
• Affects balance and coordination.
•They may walk with an unsteady gait with feet
far apart, and they have difficulty with
motions that require precise coordination,
such as writing.
Ataxic cerebral palsy

41. BASE OF THE SKULL

42. SKULL BASE
Skull base boundaries: Upper surface of the ethmoid
bone,orbital plate of the frontal
bone upto the ethmoid bone
Key bones:
 Orbital Plate of frontal bone
 Ethmoid bone
 Sphenoid bone
 Occipital bone

43. Skull base……contd.
Divided into three cranial fossa:
a. Anterior cranial fossa
b. Middle cranial fossa
c. Posterior cranial fossa

44. Key openings in base of the skull
Foramenspinosum
Foramen ovale
Foramen lacerum
Foramen rotundum
Foramenmagnum
Jugular foramen
Superior orbital fissure
Inferior orbital fissure
Optic canal
Hypoglossal canal
Pterygopalatine fossa
Skull base……contd.

45. Foramen rotundum
Present at the anterior
and medial part of
sphenoid bone.
Structures passing
d.Maxillary nerve
e.Emissary veins

46. Foramen ovale
Located in the anterior
part of sphenoid
bone,posterolateral to
foramen rotundum
Structures passing
• Mandibular nerve
•Accessory meningeal
artey
• Lesser petrosal nerve
• Emissary veins

47. Foramen spinosum
Foramen spinosum
may be absent in 2% of
the cases.
Situated
posterolateral to
foramen ovale
Transmits following
structures
•Middle meningeal
artery
•Nervous spinosus from
mandibular nerve
• Middle meninigeal vein

48. Foramen magnum
Latin”great hole” is
present in the occipital
bone
It transmits
•Medulla
oblongata,vertebral
arteries
•Anterior and Posterior
spinal arteries
• Spinal accessory nerve
•Membrana tectoria,Alar
ligaments.

49. Superior Orbital Fissure
•CN III, IV, V1, VI
•Middle meningeal artery-
orbital branch
• Recurrent meningeal artery
• Superior opthalmic vein
Jugular foramen
 Anterior compartment
• Inferior petrosal sinus

•

•
•
intermediate compartment
Cranial nerve IX,X,XI
Posterior compartment
Internal jogular vein
Meningeal branches of
occipital and ascending
pharyngeal artery