The nervous system is divided into the supratentorial and infratentorial divisions based on the location of the tentorium. The diencephalon is supratentorial while the brainstem is infratentorial. Neurons consist of a cell body with dendrites that carry impulses toward the cell body and an axon that carries impulses away. All nerves in the peripheral nervous system contain a neurilemma membrane. Gray matter lacks myelin while white matter contains myelinated nerves. The brain is divided into lobes including the frontal, parietal, occipital, and temporal lobes.

1. NERVOUS SYSTEM

7. On the basis of the location of the tentorium
(the double layer of inner dura mater located
between the cerebellum and cerebral hemispheres)
the brain is separated into supratentorial and
infratentorial divisions.
Thus, the diencephalon is supratentorial in location,
whereas the brainstem is infratentorial.

10. Neurons
• Most neurons consist of a
cell body and extensions
called dendrites and axons.
• Cell Body contains the
nucleus
• Dendrites carry impulses
towards cell body
• Axons carry impulses away
from the cell body

13. All nerves within the PNS contain a thin membrane
called the neurilemma
• Neurilemma promotes the regeneration of damaged
axons
• Grey Matter
– Nerves in the brain and spinal cord (CNS)that lack
myelin and neurilemma
• White matter
– Nerves in the brain and spinal cord (CNS) that contain
myelin and neurilemma

14. • Neuron
• The basic conducting element in the nervous system is the nerve
cell, or neuron
Ganglia. Sensory ganglia are found outside the central nervous system
• Nuclei. Throughout the brain and spinal cord there are groupings of
neurons
• with a common functions; these are the nuclei.
• Lamina. In the cerebral cortex, cerebellar cortex, and superior
colliculus, the
• gray matter is on the surface and organized anatomically into
horizontal columns
• and physiologically into vertical columns permitting a nearly infinite
number of
• interconnections.

15. Ganglia
• Groups of neuron cell bodies that lie within the
PNS
• Not included with nerves since nerves only
contain axons and dendrites

16. Senses

17. 11.5: Brain
• Functions of the brain: • Major parts of the brain:
• Interprets sensations • Cerebrum
• Determines perception • Frontal lobes
• Stores memory • Parietal lobes
• Reasoning • Occipital lobes
• Makes decisions • Temporal lobes
• Coordinates muscular movements • Insula
• Regulates visceral activities • Diencephalon
• Determines personality • Cerebellum
• Brainstem
• Midbrain
• Pons
• Medulla oblongata 17

18. CEREBRUM
The highest of human functions involve the
intricate circuitry of the cerebral cortex, which
has crucial roles in language, conceptual
thinking, creativity, planning, and the ways in
which we give form and substance to our
thoughts.

19. Structure of the Cerebrum
• Corpus callosum
• Connects cerebral
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hemispheres (a commissure) Central sulcus Parietal lobe
Gyrus
• Gyri Sulcus
• Bumps or convolutions Frontal lobe
Lateral sulcus Occipital lobe
• Sulci Transverse
• Grooves in gray matter Temporal lobe fissure
Cerebellar
• Central sulcus (a)
hemisphere
• Fissures
Central sulcus
Parietal lobe
• Longitudinal: separates the
Central sulcus
cerebral hemispheres Longitudinal
• Transverse: separates fissure
Parietal lobe
Frontal lobe Occipital lobe
Insula
cerebrum from cerebellum Occipital lobe Retracted
temporal lobe
• Lateral fissure of Sylvius (b) (c)
19

20. CEREBRUM
The hemispheres are
marked on the surface,
by slitlike incisures called
sulci
The term fissure is
sometimes used to
designate a particularly
deep and constant sulcus.
The raised ridge between
two sulci is a gyrus.

21. Cerebrum specialization
• Regions specialized for different functions
• Lobes
frontal parietal
– frontal
• speech,
control of emotions
– temporal
• smell, hearing
– occipital
• vision
– parietal
• speech, taste
reading occipital
temporal
2003-2004

22. The hemispheres are
separated from one another
in the midline by the
longitudinal fissure (Fig.
1.4).
Each hemisphere is
conventionally divided into
six lobes:
frontal, parietal, occipital, te
mporal, central (insula), and
limbic (Figs. 1.3 and 1.7).

23. Lobes of the Cerebrum
• Five (5) lobes bilaterally: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Frontal lobe Central sulcus
• Parietal lobe Parietal lobe
• Temporal lobe
• Occipital lobe
• Insula aka ‘Island of Occipital lobe
Reil’ Frontal lobe
Insula
Retracted
temporal lobe
(c)
23

25. • The lobes are
delineated from each
• other by several major
sulci

26. The lateral sulcus is a deep furrow that extends
posteriorly from the basal surface of the brain
along the lateral surface of the hemisphere, to
terminate usually as an upward curve within the
inferior part of the parietal lobe (Figs. 1.2 and
1.3).
The central sulcus of Rolando extends
obliquely from the region of the lateral sulcus
across the dorsolateral cerebral surface and, for
a short distance, onto the medial surface (Figs.
1.2 to 1.7).
The cingulate sulcus is a curved cleft
on the medial surface extending parallel to the
curvature of the corpus callosum.
The parietooccipital
sulcus is a deep cleft on the medial
surface located between the central sulcus and
the occipital pole (Fig. 1.7).

28. The boundaries of the lobes on the lateral cerebral surface are as follows: (1) The
frontal lobe is located anterior to the central sulcus and above the lateral sulcus;
(2) the occipital lobe is posterior to an imaginary line parallel to the parietooccipital
sulcus, which is on the medial surface;
(3) the parietal lobe is located posterior to the central sulcus, anterior to the imaginary
parietooccipital line, and above the lateral sulcus and a projection toward the occipital
pole before it takes an upward curve;
(4) the temporal lobe is located below the lateral sulcus and anterior to the imaginary
parietooccipital line; and
(5) the central lobe is located at the bottom (medial surface) of the lateral sulcus of
Sylvius, which is actually a deep fossa (depression). It can be seen only when the
temporal and frontal lobes are reflected away from
the lateral sulcus.

29. The boundaries of the lobes on the medial cerebral surface (Fig. 1.7) are as
follows:
(1) The frontal lobe is located rostral to a line formed by the central sulcus;
(2) the parietal lobe is between the central sulcus and the parietooccipital
sulcus;
(3) the temporal lobe is located lateral to the parahippocampal gyrus;
(4) the occipital lobe is posterior to the parietooccipital sulcus;
and
(5) the limbic lobe is a synthetic one formed by parts of the
frontal, parietal, and temporal lobes.
It is located central to the curved line formed by the cingulate sulcus and the
collateral sulcus (the latter is located lateral to the parahippocampal gyrus).

33. The cell bodies of the pyramidal
neurons and stellate (granule)
neurons are present in laminae II
through VI.

34. In general, the main input
layers of the cortex are
laminae I through IV. The
main output is from
laminae V and VI.

35. Primary Motor Cortex
• The neocortex has been parceled in several
• ways; the most commonly used scheme is that
• of Brodmann
• The primary motor cortex is located in area
• 4 of the precentral gyrus

36. Gray Matter vs. White Matter
• Gray Matter – Absence of myelin in
masses of neurons accounts for the gray
matter of the brain – Cerebral Cortex
• White Matter - Myelinated neurons gives
neurons a white appearance – inner
layer of cerebrum

38. Premotor Cortex and Supplementary
Motor Area
• The premotor cortex consists of areas 6 and
• 8.
• The supplementary motor area is in area 6 on
the medial aspect of the frontal lobe.

39. • The primary somatic sensory (somatosensory)
• cortex (SI) includes the postcentral gyrus
• and its medial extension in the paracentral
• gyrus (areas 3, 1, and 2 of the parietal lobe

40. • The cortical map of areas 3, 1, and 2
(postcentral
• gyrus) comprises detailed somatotopically
• organized modality-specific columns that
• represent various submodalities.

41. • The secondary somatic sensory area (SII) is
• located on the superior bank of the lateral
fissure
• below the primary motor and sensory areas.
• SII is topographically organized with
• respect to such general sensory modalities as
• touch, position sense, pressure, and pain.

42. • Areas 5, 7,
• and 40 of the parietal lobe comprise the
• somatosensory association cortex.

44. • Taste is represented in area 43
• Visual Cortex
• The primary visual cortex (area 17),
• The extrastriate association cortex includes
• visual area II (area 18), visual area III (area 19),
• angular gyrus (area 39), and inferotemporal
• cortex (areas 20 and 21)
• Through corticotectal fibers, the so-called
• occipital eye field of areas 18 and 19 mediate
• slow pursuit and vergence eye movements

48. • Auditory Cortex
• The primary auditory cortex (area 41) is
• located in the temporal lobe in the transverse
• gyri of Heschl on the floor of the lateral fissure
• Auditory area II (area 42) has a higher threshold
• to sound intensity than the primary cortex
• There are at least five auditory cortical areas in
• the temporal lobe, including area 22 of the
• superior temporal gyrus. Patients with lesions
• of area 22 on the dominant side have profound
• difficulty in the interpretation of sounds;

50. • (1) the visual cortex (areas 17, 18, and 19)
• to (2) the angular gyrus (area 39) to (3)
Wernicke’s area (area 22) via (4) the arcuate
fasciculus to
• (5) Broca’s speech areas 43 and
44, and, finally, (6) to the motor area 4, where
the descending
• motor pathways involved with vocalization
originate

52. Basal Nuclei
• Masses of gray matter Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Deep within cerebral Longitudinal
fissure
hemispheres Caudate Right cerebral
• Caudate
nucleus hemisphere
Basal Putamen
nuclei
nucleus, putamen, and Globus
pallidus
globus pallidus
• Produce dopamine Thalamus
Cerebellum
• Control certain muscular Hypothalamus
Brainstem Spinal cord
activities
• Primarily by
inhibiting motor
functions
52

53. Basal Ganglia
• The term basal ganglia refers to several
• subcortical nuclei together with a nucleus of
• the diencephalon and a couple in the midbrain
• These are
• the caudate nucleus, lenticular nucleus, subthalamic
• nucleus, and substantia nigra.
• The caudate nucleus and
• the lenticular nucleus are collectively called
• the corpus striatum; they are the deep nuclei of
• the cerebral hemispheres. The lenticular nucleus
• is subdivided into the putamen and globus
• pallidus (pallidum, paleostriatum). The putamen
• and the caudate nucleus are called the
• striatum (neostriatum). The subthalamic nucleus
• is located within the ventral thalamus (Chap.
• 23). The substantia nigra is a nucleus located
• within the midbrain

56. • The basal ganglia are nuclear complexes in
• the cerebrum and midbrain that play a critical
• role in the integration of motor activity

60. The Limbic System

61. Hippocampus
• Involved in the
processing and
storage of
memories.

62. Amygdala
• Involved in how
we process
memory.
• More involved
in volatile
emotions like The emotion of anger has not changed much
anger. throughout evolution.

65. • A whitish structure is seen in the depths of the
fissure
• — the corpus callosum
• The corpus callosum is the largest of the
commissural
• bundles, as well as the latest in evolution.

66. • The temporal lobe extends medially toward
the midbrain
• and ends in a blunt knob of tissue known as
the
• uncus.

68. General Organization of the Basal
Ganglia
• On the basis of their neural connections, the
• nuclei of the basal ganglia are organized as
• input nuclei, intrinsic nuclei, and output nuclei
• (see Table 24.2). The input nuclei receive
• afferent information from outside the basal
• ganglia and project their output to the intrinsic
• nuclei. The intrinsic nuclei interact and have
• connections with both other input nuclei and
• output nuclei. After neural processing within
• the basal ganglia, the output nuclei send
• inhibitory signals to nuclei outside the basal
• ganglia.

70. Diencephalon
• Between cerebral hemispheres and above the brainstem
• Surrounds the third ventricle
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Superior
colliculus
• Thalamus Corpora quadrigemina
Optic chiasma
Inferior
Optic nerve colliculus
• Epithalamus Pituitary gland
Thalamus
• Hypothalamus
Mammillary body
Optic tract Third
ventricle
• Optic tracts Pons Cerebral
peduncles Pineal gland
• Optic chiasm Pyramidal tract
Fourth
ventricle
• Infundibulum Olive
Cerebellar
• Posterior pituitary
peduncles
Medulla
oblongata
• Mammillary bodies Spinal cord
• Pineal gland (a) (b)
70

71. Diencephalon
• The diencephalon, located in the ventromedial
• portion of the cerebrum, is continuous caudally
• with the midbrain
• It consists of
• four subdivisions: epithalamus, thalamus (dorsal
• thalamus), hypothalamus, and ventral thalamus
• (subthalamus).

72. • The epithalamus, choroid plexus of the third
ventricle (Fig. 1.5), and the
• pineal body (Fig. 1.8) form the upper margin
• (roof) of the diencephalon. Ventral to the
thalamus
• is the hypothalamus, which includes the
• mamillary bodies, and the hypophysis (pituitary
• gland) (Figs. 1.5 and 1.9). The ventral
• thalamus is located lateral to the hypothalamus.

75. • The thalamus is located between the third
• ventricle medially and the posterior limb of
the
• internal capsule laterally
• The thalamus
• consists of several groups of nuclei.

77. • The hypothalamus is strategically located
• between the cerebrum and the brainstem

78. Diencephalon
• Thalamus
• Gateway for sensory impulses heading to cerebral cortex
• Receives all sensory impulses (except smell)
• Channels impulses to appropriate part of cerebral cortex for
interpretation
• Hypothalamus
• Maintains homeostasis by regulating visceral activities
• Links nervous and endocrine systems (hence some say the
neuroendocrine system
78

79. Internal Capsule
• The internal capsule is a massive bundle of
• nerve fibers, which contains almost all of the
• fibers projecting from the subcortical nuclei to
• the cerebral cortex and from the cerebral cortex
• to subcortical structures in the
cerebrum, brainstem,
• and spinal cord (Fig. 13.4). It is divided
• into an anterior limb, genu, and posterior limb

82. • The anterior (caudatolenticular)
• limb is located between the caudate nucleus
• and the lenticular nucleus. The genu (knee) is
• located between the anterior and posterior
• limbs. The posterior (thalamolenticular) limb
• is located between the thalamus and lenticularnucleus.
The retrolenticular (postlenticular)
• part of the posterior limb is located lateral to
• the thalamus and posterior to the lenticular
• nucleus and the sublenticular part is ventral to
• the lenticular nucleus.

83. Reticular Formation
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• Complex network of nerve Hypothalamus
Diencephalon
fibers scattered throughout the Thalamus
brain stem
• Extends into the diencephalon Corpus
• Connects to centers of callosum
hypothalamus, basal
nuclei, cerebellum, and cerebrum
• Filters incoming sensory Corpora
quadrigemina
information
• Arouses cerebral cortex into Midbrain Cerebral
state of wakefulness Pons
aqueduct
Reticular
formation
Medulla
oblongata Spinal cord
83

84. RETICULAR FORMATION
• The RF extends throughout the length of the
• brainstem tegmentum.

85. Diencephalon
The Limbic System
• Consists of: • Functions:
• Portions of frontal lobe • Controls emotions
• Portions of temporal lobe • Produces feelings
• Hypothalamus • Interprets sensory impulses
• Thalamus
• Basal nuclei
• Other deep nuclei
85

86. LIMBIC SYSTEM
• Anatomically, the limbic system comprises
• a complex network of cortical areas and subcortical
• structures interconnected by bidirectional
• pathways. One component of the limbic
• system, the hippocampus is important in mechanisms
• of memory.

88. Brainstem
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Hypothalamus
Diencephalon
Three parts: Thalamus
1. Midbrain
2. Pons Corpus
callosum
3. Medulla Oblongata
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Pons
Reticular
formation
Medulla
oblongata Spinal cord
88

89. Brainstem: Medulla, Pons, and
Midbrain
• The brain stem is located in the posterior
cranial fossa and consists of medulla,
• pons, and midbrain.

90. Functions of the brainstem
• serves as a conduit for the ascending tracts and
descending tracts
• control of respiration and cardiovascular systems
• contains the important nuclei of cranial nerves III
through XII.

93. • • The midbrain region (mesencephalon) has
two
• large “pillars” anteriorly called the cerebral
• peduncles, which consist of millions of axons
• descending from the cerebral cortex to various
• levels of the brainstem and spinal cord.
• •

94. • The three subdivisions of the midbrain are
also clearly seen in
• these figures. Above the level of the cerebral
aqueduct lies the tectum and
• between the aqueduct and the basis
pedunculi is the grey matter of the
• tegmentum separated from basis pedunculi by
the deeply pigmented
• lamina of the substantia nigra.

95. Midbrain
• Between diencephalon and
pons
• Contains bundles of fibers Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Superior
that join lower parts of colliculus
Corpora quadrigemina
brainstem and spinal cord Optic chiasma
Inferior
Optic nerve colliculus
with higher part of brain Pituitary gland
Thalamus
• Cerebral aqueduct Mammillary body
Optic tract Third
• Cerebral peduncles ventricle
Pons Cerebral
(bundles of nerve fibers) peduncles Pineal gland
• Corpora quadrigemina Pyramidal tract
Fourth
ventricle
(centers for visual and Olive
Cerebellar
peduncles
auditory reflexes) Medulla
oblongata
Spinal cord
(a) (b)
95

96. Pons
• Rounded bulge on
underside of brainstem
• Between medulla Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Superior
oblongata and midbrain Corpora quadrigemina
colliculus
• Helps regulate rate and Optic nerve Optic chiasma
Inferior
colliculus
depth of breathing Pituitary gland
Mammillary body
Thalamus
• Relays nerve impulses to Optic tract Third
ventricle
and from medulla Pons Cerebral
peduncles Pineal gland
oblongata and cerebellum Fourth
Pyramidal tract ventricle
Olive
Cerebellar
peduncles
Medulla
oblongata
Spinal cord
(a) (b)
96

97. • The pons portion is distinguished by its bulge
• anteriorly, the pons proper, an area that is
composed
• of nuclei (the pontine nuclei) that connect
• to the cerebellum.
• Vth, VIth and VIIth cranial nerves.

98. Medulla Oblongata
• Enlarged continuation of
spinal cord
• Conducts ascending and Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Superior
colliculus
descending impulses between Corpora quadrigemina
Inferior
brain and spinal cord Optic nerve Optic chiasma colliculus
• Contains Pituitary gland
Mammillary body
Thalamus
Third
cardiac, vasomotor, and Optic tract
ventricle
respiratory control centers Pons Cerebral
• Contains various nonvital
peduncles Pineal gland
Fourth
Pyramidal tract ventricle
reflex control centers Olive
Cerebellar
(coughing, sneezing, swallowi peduncles
Medulla
ng, and vomiting) oblongata
Spinal cord
(a) (b)
98

99. • • The medulla has two distinct elevations on
• either side of the midline, known as the
pyramids;
• the direct voluntary motor pathway from
• the cortex to the spinal cord, the cortico-spinal
tract, is located within the pyramid. Behind
• each is a prominent bulge, called the olive, the
• inferior olivary nucleus, which connects with
• the cerebellum.x
• the rootlets of cranial nerves IX, X and XI

102. Cerebellum
• Inferior to occipital lobes
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• Posterior to pons and medulla Longitudinal
fissure
oblongata
• Two hemispheres Thalamus
Corpus callosum
• Vermis connects hemispheres
• Cerebellar cortex (gray matter) Superior
peduncle
• Arbor vitae (white matter) Pons
Cerebellum
• Cerebellar peduncles (nerve fiber Middle peduncle
Inferior peduncle
tracts) Medulla oblongata
• Dentate nucleus (largest nucleus in
cerebellum)
• Integrates sensory information
concerning position of body parts
• Coordinates skeletal muscle activity
• Maintains posture
102

104. Major Parts of the Brain
104

105. CEREBELLUM
BY
DR MANAH CHANDRA CHANGMAI

106. GROSS ANATOMY OF CEREBELLUM
Location:
 The term cerebellum is from
“latin meaning” the little brain.It is
a part of the hindbrain situated in
the posterior cranial fossa.
 It is also present behind the pons
and medulla ablongata,seperated
from two structures by the cavity
of fourth ventricle.
 It is covered by tentorium
cerebelli and is connected to
brain stem by three cerebellar
peduncles.
 In adults the weight ratio
between cerebellum and
cerebrum is 1:10,Infants 1:20

107. Anatomy of cerebellum......contd.
Consists of two laterally, large Horizontal fissure
Hemisphere
hemisphere which are united by midline
vermis.
Cerebellar surface is divided by
numerous curve transverse fissures giving Superior surface
it a laminated appearance
One conspicious fissure “horizontal
fissure”extends around dorsolateral Vermis
border of each hemisphere from middle
cerebellar peduncle to
vallecula,seperating superior and inferior
surface

108. External surface of cerebellum
Primary fissure
The deepest fissure in the vermis is primary
fissure, which curves ventrolaterally in the
superior surface of the cerebellum to meet
horizontal fissure.
Primary fissure divides the cerebellum into
anterior and posterior lobe.
Anterior lobe
Primary fissure
Posterior lobe

109. External surface of cerebellum
Horizontal fissure
vermis
Primary fissure
Hemisphere

110. Arbor vitae cerebelli
Arbor vitae
•In latin “ tree of life” it is the white matter
of the white matter of cerebellum.
•It is so called because of the tree like
appearance.
•It brings sensory and motor
sensation to and from cerebellum.
Fourth ventricle

111. The cerebellum is connected to
Brain stem by three peduncles
Superior cerebellar peduncle
Midbrain
Middle cerebellar peduncle
Pons
Inferior cerebellar peduncle
Medulla ablongata

112. Peduncles of the cerebellum

113. Parts of the cerebellum
Vermis
Hemisphere

114. LOBES OF CEREBELLUM
Inferior surface
Anterior lobe
Divisions of lobes
Anatomical Posterior lobe
Flocculonodular lobe
Anterior lobe Flocculonodular lobe
Posterior lobe
Superior surface
Anterior lobe
Posterior lobe

115. Division of lobes…..contd.
Functional(Evolutionary)
 Paleocerebellum
 Neocerebellum
 Archicerebellum

116. Archi-cerebellum
posterior lobe
(Vestibular part)
•It is formed of the flocculo-
nodular lobe + associated
fastigial nuclei, lying on inf.
Surface in front of postero-lateral
fissure.
•Embryologically, it is the oldest
part of cerebellum.
•It receives afferent Fibres. From
vestibular apparatus of internal ear
Via vestibulo-cerebellar tracts.
•It is concerned with equlibrium
Neocerebellum
Archicerebellum
Paleocerebellum

117. Archicerebellum …….contd.
It has connections with vestibular &
reticular nuclei of brain stem through
the inferior cerebellar peduncle.
Afferent vestibular Fibres. Pass from
vestibular nuclei in pons & medulla to
the cortex of ipsilateral flocculo-nodular
lobe.
Efferent cortical (purkinje cell) Fibres.
Project to fastigial nucleus, which
projects to vestibular nuclei & reticular
formation.
It affects the L.M.system bilaterally via
descending vestibulo-spinal & reticulo-
spinal tracts.

118. Paleo-cerebellum
(spinal part) :
•it is formed of midline
vermis + surrounding
paravermis + globose &
emboliform nuclei.
•It receives afferent proprio-
ceptive impulses from Ms.&
tendons Via spino-cerebellar
tracts (dorsal & ventral)
mainly.
•it sends efferents to red
nucleus of midbrain.
•it is concerned with muscle Paleocerebellum
tone

119. It is concerned with muscle tone
& posture.
. Afferents spinal Fibres consist of
dorsal & ventral spino-cerebellar
tract from muscle, joint &
cutaneous receptors to enter the
cortex of ipsilateral vermis & para
vermis Via inferior & superior
cerebellar peduncles .
Efferents cortical fibres pass to
globose & emboliform nuclei, then
Via sup. C. peduncle to contra-
lateral red nucleus of midbrain to
give rise descending rubro-spinal
tract.

120. Neo-cerebellum
(cerebral part)
•It is the remaining largest part
of cerebellum.
•It includes the most 2-cerebellar
hemispheres + dendate nuclei.
•It receives afferent impulses
from the cerebral cortex+pons
Via cerebro-ponto- cerebellar
pathway.
•it sends efferents to Ventro
lateral nucleus of thalamus.
•it controls voluntary movements Neocerebellum
(muscle coordination).

121. It is concerned with muscular
coordination.
It receives afferents from cerebral
cortex involved in planning of
movement- to pontine nuclei ,cross to
opposite side Via middle Cerebellar
peduncle to end in lateral parts of
cerebellum (cerebro-ponto-cerebellar
tract).
Neo-cerebellar efferents project to
dendate nucleus,which in turn projects
to contra-lateral red nucleus & ventral
lateral nucleus of thalamus ,then to
motor cortex of frontal lobe, giving rise
descending cortico-spinal & cortico-
bulbar pathways.
Efferents of dentate nucleus form a
major part of superior C. peduncle.

122. Other types of Divisions
 Afferent regions
— Spinocerebellum
— Pontocerebellum
 Efferent regions
— Vestibulocerebellum
— Lateral Hemisphere

123. Summary of classification
Archicerebellum
Classification by phylogenetic
Ontogenic development Nodulus
Archicerebellum
Archicerebellum flocculus
Paleocerebllum
Neocerebellum Palaeocerebellum
Classification by Afferent Connection Neocerebellum
Vestibulocerebellum
Spinocerebellum
Pontocerebellum
Spinocerebellum
Classification by Efferent Connection
Vermis Pontocerebellum
Paravermal Region
Cerebellar Hemisphere
Vestibulocerebellum

124. Structure of the cerebellum Cortex
Medulla

125. Subdivision of lobes
Subdivision of Flocculonodular lobe
Vermis Hemisphere
Nodulus Flocculus Nodulus Flocculus
Subdivision of Anterior lobe
Lingula
Central lobue
Vermis Hemisphere Ala of central lobule
Lingula
Central lobule Ala of the central
l
lobule

126. Posterior lobe
Vermis Hemisphere
Declive Simple lobule
Simple lobule
Postcentral fissure Declive
folium
Vermis Hemisphere
Folium Superior semilunar lobule
Horizontal fissure
Vermis Hemisphere
Tuber Inferior semilunar lobule
uvula
Gracile lobule
Tuber

127. Vermis Hemisphere
Pyramid Biventral lobule
Uvula Tonsil

130. Superior surface
Ant lobe
Post lobe
Inferior surface
Post lobe
Ant lobe

131. Structure
 Cerbellum consists of outer
layer of grey matter known
as cortex and inner layer of
white matter known as
medulla.
 The medullary core is
composed of incoming and
outgoing fibres projecting to
and from the cerebellar
cortex.
 Medullary core also contain
the nucleuses of the
cerebellum which are four in
number.

132. Structure of cerebellum Medulla Cortex

133. Structure of cerebellar……contd.
Cerebellar Cortex
Molecular Layer
Purkinje Cell Layer
Granular Layer
Corpus Medullare (Medullary Center)
Deep Cerebellar Nuclei
Fastigial Nuclei
Nucleus Interpositus
Emboliform Nucleus
Globose Nucleus
Dentate Nucleus

134. CEREBELLUM cortex
• Cerebellar Cortex
• I. Molecular Layer
• Stellate Cell --- taurine
(inhibitory)
• afferent: parallel fiber
• efferent: Purkinje cell
dendrite
• Basket Cell ---- GABA
(inhibitory)
• afferent: parallel fiber
• efferent: Purkinje cell soma
•
• Parallel Fiber
• granule cell axon
• Purkinje Cell Dendrite

135. Cerebellum layers……contd.
• II. Purkinje Cell Layer
• Purkinje Cell
• -- 15,000,000 in number
• -- GABA (inhibitory)
• afferent: parallel fiber
• climbing fiber
• stellate cell
• basket cell
• efferent: deep cortical
nuclei
• Bergman’s glial cell

136. Purkinje cells
flaskshaped cell, single layered
Dendrites
-Molecular layer
- profuse branching
- dendritic spines
Axon
- synapse with deep cerebellar
nucleus
- basket & stellate cells
- vestibular nuclei

137. Cerebellum layers……..contd.
• III. Granular Layer
• Granular Cell
• -- 50,000,000,000 in number
• -- glutamic acid (excitatory)
• afferent: mossy fiber
• efferent: Purkinje cell axon
• basket cell,
stellate cell
• Golgi cell
• Golgi Cell
• -- GABA (inhibitory)
• afferent: parallel fiber,
mossy fiber rosette
• efferent: granule cell
dendrite

138. Climbing fibres
- from inferior olivary complex
- direct action on individual Purkinje cell
- powerful , sharply localised
- Basket cells, stellate cells, Golgi cells act
as inhibitory interneurons.
Mossy fibres
-from spinal cord / brain stem centres
-indirect action on Purkinje cells via
granule cells
-diffuse
( thousands of Punkinje cells may be excited )

139. White matter of the cerebellum
 Consists of three types of nerve fibres in the white matter
A. Axons of purkinje cells
The only axons to leave cerebellar cortex to end in deep
cerebellar nuclei specially dendate nucleus.
B. Mossy fibres
They end in the granular layer.
C. Climbing fibres
They end in the molecular layer

140. White matter of cerebellum
The internal circuity of cerebellum
 Donot leave the cerebellum,interconnect
different regions of cerebellum.
 Some connect the same side.
 Some connect the two cerebellar hemisphere
The cerebellar efferent via middle cerebellar
peduncle(MCP) and inferior cerebellar peduncle
(ICP)
The cerebellar afferent via superior cerebellar
peduncle(SCP) and from fastigial from inferior
cerebellar peduncle(ICP)

141. Intrinsic pathway
Afferent pathways to cerebellar
cortex excite Purkinje cells.
Basket, stellate and Golgi cells
regulate Purkinje cell activity
Efferent pathways from the
cerebellar cortex originate from
Purkinje cells -

142. Intrinsic pathway

144. Cerebellar AFFERENT pathway
From cerebral cortex
cortico-ponto-cerebellar fibres
cerebro-olivo-cerebellar fibres
cerebro- reticulo- cerebellar fibres
From spinal cord
anterior spinocerebellar tract
posterior spinocerebellar tract
cuneocerebellar tract
From vestibular nucleus
vestibulocerebellar tract [
flocculonodular lobe ]
From other areas
red nucleus, tectum

145. Afferent pathway origin Destination via
Corticopontocerebellar Frontal,parietal, Pontine nuclei &
temporal, mossy fibres to
occipital cerebellar cortex
Cerebroolivocerebellar INF olivary N & climb
fibres to cerebellar
cortex
Cerebroreticulocerebellar Sensorimotor Reticular formation
areas
Ant spinocerebellar Muscle Mossy fibres to
spindles,tendons, cerebellar cortex
Post spinocerebellar joints
Cuneocerebellar
Vestibular nerve Utricle, Mossy fibres to
saccule,semicircu cortex of FN node
lar canals
others Red nuc, tectum cerebellar cortex

146. Cerebellar EFFERENT pathways
• Axons of Purkinje cells
synapse with the cerebellar nuclei.
• Axons of the neurones form the
efferent pathways
Connect with
• Red nucleus
• Thalamus
• Vestibular nuclei
• Reticular formation

147. Histological structure of cer

148. Histology of the cerebellum…..contd
Molecular layer
Purkinje layer
Granular layer

149. Cerebellar cortex…..contd.
• Synaptic Glomerulus
• Afferent terminals on granular
layer
•  Mossy Fiber Rosette
• -- afferent fibers except
• inferior olivary input
• -- 2/3 of medullary center
•  Granular Cell Dendrite
• -- main afferent input
•  Golgi Cell Axon
• -- synapse on granule cell
dendrite
• -- GABA (inhibitory)
• - Surrounded by Astrocyte
Foot Process

150. Cerebellar structure……Deep nuclei
• 1. fastigial
• nucleus
• 2. globose
• nucleus
• 3. emboliform
• nucleus
• 4. dentate
• nucleus

151. Deep nucleuses of cerebellum
Dentate nucleus
Emboliform nucleus
Globose nucleus
Nucleus interpositus Fastigial nucleus

152. Fibres entering and leaving through cerebellar peduncles
Superior cerebellar peduncle
Superior cerebellar peduncle
A. Fibres entering the cerebellum
1. Ventral spino-cerebellar tract
2. Rostral spino-cerebellar tract
3. Tecto-cerebellar fibres
4. Rubro-cerebellar fibres
5. Trigemino-cerebellar fibres
6. Hypothalamo-cerebellar fibres
7. Coerulo-cerebellar fibres
B. Fibres leaving the cerebellum
1. Cerebello-rubral fibres
2. Cerebello-thalamic fibres
3. Cerebello-reticular fibres
4. Cerebello-olivary fibres
5. Cerebello-nuclear fibres
6. Some fibres to hypothalamus
and thalamus

153. Middle cerebellar peduncle
Pontocerebellar fibres
Middle cerebellar peduncle
Inferior cerebellar peduncle
A. Fibres entering cerebellum
1. Posterior spino cerebellar tract
2. Cuneo-cerebellar tract
3. Olivo-cerebellar fibres
4. Reticulo-cerebellar fibres
5. Vestibulo-cerebellar fibres
6. Anterior external arcuate fibres
7. Fibres of striae medullaries
8. Trigemino-cerebellar fibres
B. Fibres Leaving the cerebellum
1. Cerebello-olivary fibres
2. Cerebello-vestibular fibres
Inferior cerebellar peduncle
3. Cerebello spinal and cerebello reticular
fibres

154. Classification of cerebellum
• Classification by phylogenetic and
Ontogenic development Archicerebellum
Nodulus
• Archicerebellum
• Paleocerebllum Archicerebellum
• Neocerebellum flocculus
Palaeocerebellum
• Classification by Afferent
Connection Neocerebellum
• Vestibulocerebellum
• Spinocerebellum
• Pontocerebellum
Spinocerebellum
• Classification by Efferent
Connection
• Vermis Pontocerebellum
• Paravermal Region
• Cerebellar Hemisphere
Vestibulocerebellum

155. CT SCAN OF BRAIN WITH CEREBELLUM

156. MRI OF BRAIN WITH CEREBELLUM

157. Functions of cerebellum
 Maintenance of Equilibrium
- balance, posture, eye movement
 Coordination of half-automatic
movement of
walking and posture maintenace
- posture, gait
 Adjustment of Muscle Tone
 Motor Leaning – Motor Skills
 Cognitive Function

158. Balance

159. Motor skills

160. Syndromes
Ataxia: incoordination of movement
- decomposition of movement
- dysmetria, past-pointing
- dysdiadochokinesia
- rebound phenomenon of Holmes
- gait ataxia, truncal ataxia,
titubation
Intention Tremor
Hypotonia, Nystagmus
Archicerebellar Lesion:
medulloblastoma
Paleocerebellar Lesion: gait
disturbance
Neocerebellar Lesion: hypotonia, ataxia,
tremor

161. Cerebellar Ataxia
Ataxic gait and position:
Left cerebellar tumor
a. Sways to the right in
standing position
b. Steady on the
right leg
c. Unsteady on the
left leg
d. ataxic gait

162. Cerebellar Medulloblastoma
Cerebellar tumors on vermis
- Truncal Ataxia
- Frequent Falling
The child in this picture:
- would not try to stand
unsupported
- would not let go of the bed rail
if she was stood on the floor.

163. Cerebellar lesions
Are usually vascular, may be traumatic or tumour.
Manifestations of unilateral cerebellar lesions :
1-ipsilateral incoordination of (U.L) arm = intention tremors : it is a
terminal tremors at the end of movement as in touching nose or button the
shirt.
2-Or ipsilateral cerebellar ataxia affects (L.L.) leg, causing wide-based
unsteady gait.
Manifestations of bilateral cerebellar lesions (caused by alcoholic
intoxication, hypothyrodism, cerebellar degeneration & multiple
sclerosis) 1-dysarthria : slowness & slurring of speech.
2-Incoordination of both arms.= intention tremors.
3-Cerebellar ataxia : intermittent jerky movements or staggering ,wide-
based, unsteady gait
4-Nystagmus : is a very common feature of multiple sclerosis. It is due to
impairment coordination of eye movements /so, incoordination of eye
movements occurs and eyes exhibit a to-and-fro motion.
Combination of nystagmus+ dysarthria + intension tremors constitutes
Charcot’triad, which is highly diagnostic of the disease.

164. THANK YOU