this presentation covers basic anatomy and physiology of brain, with detailed information about microscopic structures that make up the CNS.

2. INTRODUCTION
Brain is the primary organ involved in
nervous system

3. Classification

5. Brain
Cerebrum
Cerebral
cortex
Corpus
collosum
Cerebellum Diencephalon
thalamus
Pineal body
hypothalamus
Brain stem
Mid brain
Pons
Medulla
oblongata

6. Brain
Cerebrum
Cerebral
cortex
Corpus
collosum
Diencephalon
thalamus
Pineal body
hypothalamus
Brain
stem
Midbrain
pons
Medulla
oblongata Cerebellum

7. Cerebrum
Cerebrum is the largest part of the brain ,
It is divided into right and left cerebral hemisphere by
longitudinal fissure .
The two parts of cerebral hemisphere are connected
by a mass of white matter called corpus collosum.
Superficial part of cerebrum is made up of grey matter
which forms cerebral cortex.

9. Tracts of cerebrum

10. Tracts
1. Association Tract- Connects different part of hemisphere.
Extending from one gyrus to another
2. Commissural tracts- It connects corresponding areas of
two cerebral hemisphere, e.g.- Corpus collosum
3. Projection tracts- It connects cerebral cortex with grey
matter with lower part of brain and spinal cord
4. Corticospinal Tracts- the motor fibres within internal
capsule forms the pyramidal tracts (corticospinal tracts)

11. Internal Capsule
Internal capsule is an important projection tract that lies
within the brain between the basal ganglia and thalamus
Fibers of internal capsule carries the nerve impulses passing
to and from cerebral cortex
Corticospinal tracts decussate at the medulla oblongata
Motor fibres that do not pass over internal capsule forms
extrapyramidal tracts

12. Basal Ganglia
There is a group of cell bodies deep within cerebral
hemisphere called nuclei.
Some of these nuclei forms basal ganglia which forms
extrapyramidal tracts.
They act as relay station that connects to many parts of
the brain.
They initiate complex movement.

13. Cerebral Cortex
Superficial part of cerebrum forms cerebral cortex
made up of grey matter
It is involved in higher order function such as learning ,
memory, thinking decision making
It is active in sensory perception such as pain,
temperature, touch, hearing, taste and smell
It is also involved in voluntary movement of skeletal
muscle

14. Functional
areas
Motor area
Skeletal
Muscle
Sensory
area
Sensory
Perception
Association
area
Complex
Mental
Function

15. Functional Areas of Cerebral Cortex
Wernicke‘s
(sensory speech)
area
Auditory areaTaste area
pre motor area
Somato sensory
area
Broca’s (motor
speech) area
Primary motor
area
Visual area

16. Motor area
Primary motor area Broca’s (motor speech)
area
In this area the body is represented
upside down the uppermost cell controls
the feet and vice versa
the size of areas of cortex are
proportional to the complexity of
movement of body parts.
There are two neurons involved in
pathways to skeletal muscle
 UPPER MOTOR NEURON descends
through internal capsule to the
medulla oblongata and decussate and
synapses to
 LOWER MOTOR NEURON that leaves
spinal cord and travel's to target
muscle
This area is situated in the frontal lobe
just above the lateral sulcus
It controls muscle movement involved
in muscle movement needed for speech
In right handed people the left side of
this area is more dominant

17. Somato
sensory
• This area
lies behind
central
sulcus
• It receive
signals of
pain
temperature
pressure
and touch .
Auditory
•Present
below lateral
sulcus
• This area
receive
impulse from
8th cranial
nerve
Olfactory
• It lies deep
within
temporal
lobe
• it recieves
impulses
from nose
via 1st
cranial
nerve
(olfactory
nerve )
taste
• This lies just
above
lateral
sulcus
• It receive
impulses
from taste
buds
visual
• This lies
behind
parieto
occipital
sulcus
• Optic nerves
pass from
this area .
Sensory area

18. Association areas
Premotor
area
• The neurons
coordinate
movement
initiated by
primary
motor cortex.
Prefrontal
area
• It is a large
area
• Developed
more highly
in humans
• Intellectual
function are
controlled
here.
Sensory
speech area
• This area is
associated
with
language
perception.
Parieto
occipital
area
• This area is
involved in
spatial
awareness
language
interpretatio
n and naming
of object.

19. Thalamus
• They are two
masses of grey
and white matter
• The thalamus
relays and
redistributes
impulses from
most part of the
brain to the
cerebral cortex
Hypothalamus
• Hypothalamus
consist of nuclei
• It is linked to the
posterior lobe of
the pituitary
gland by complex
system of blood
vessels
Diencephalon

20. Mid brain
• It is situated
around cerebral
aqueduct
• It consist of nuclei
and nerve fibres
(tracts)
• These tracts
connect cerebrum
with lower part of
the brain and with
the spinal cord
• They help in visual
and auditory
reflexes
Pons
• It is situated in
front of cerebellum
pons contains
white matter that
forms bridge
between the 2
hemisphere of
cerebellum
• Pons act as relay
station and some
of the part forms
apnoustic and
pneumotoxic
centres
Medulla oblongata
• It is the most
interior portion of
brain stem and is
continues with
spinal cord
• Outer structure of
medulla are
composed of white
matter and grey
matter centrally

21. Features of Medulla oblongata
• In this motor nerves descend from motor
area in the cerebrum to the spinal cord in
the corticospinal tracts
Decussation (crossing)
• Crossing over of sensory nervesSensory decussation
• This centre controls the rate and force of
cardiac contraction, it controls blood
pressure. It has Vasomotor centres
Cardio Vascular
Centre
• This area control rate of respiration,
these centres are connected with
Intercostal nerves which control
intercostal muscle
Respiratory System
•Certain irritants present in stomach or
respiratory tract stimulate the Reflex
Centres ( vomiting, gagging, coughing and
sneezing)
Reflex centres

22. cerebellum
 The cerebellum is situated behind the pons and
immediately below posterior portion of cerebrum
 It occupies posterior cranial fossa
 Grey matter forms outer portion and white matter
lies deep

23. Functions of Cerebellum
Cerebellum controls and coordinates the
movement of various group of muscle
Maintenance of posture, balance and
equilibrium
They also have a role in language processing

24. Grey matter and White matter
 GREY MATTER  WHITE MATTER
Grey matter is formed by nerve cell
body, dendrites and terminal
knobs
Grey matter is grey in color because
of grey nuclei
Grey matter is involved in learning
and complex function
Grey matter is responsible for
cognitive function
White matter is formed only by axons
White matter is white in color because
of myelin
White matter is involved
in insulation of neuron
White matter transfers impulses to
and from grey matter

26. Cell bodies form the grey matter of the
nervous system
They are present at the periphery of the
brain and in center of spinal cord
In CNS cell bodies are called nuclei
In PNS cell bodies are called ganglia

27. Dendrites form parts of synapses in motor
neuron
Dendrites form sensory receptors in
sensory receptors

28. Axons are extensions of cell bodies and are
found deep in brain called tracts.
Group of axons in spinal cord are called
nerve or nerve fibers.
They form the white matter of the nervous
system.

30. Oligodendrocytes are found in clusters around nerve cell
bodies in grey matter.
They have supportive function.
They are present adjacent to and along length of myelinated
nerve fibers.
They aid in transmission of impulses

31. These cells form Ventricle of brain
These cells also form central canal in spinal chord
Choroid plexus inside ventricles are formed by Ependymal
cells
Choroid plexus is a vascular area surrounded by Ependymal
cells

32. Microglia
They are present mainly in area of blood vessels
These cells are derived from monocyte
They have phagocytic action in area of inflammation
and cell destruction

34. Action Potential
 Action potential is defined as transmission of nerve impulses.
 Action potential arises due to movement of ions across nerve cell
membrane.
 K+(potassium) is present inside the membrane(intracellular cation)
 Na+ (sodium) is present outside the membrane (extracellular cation )

35.  During stimulation the permeability of these membrane changes and
Na+ ions flood in causing depolarization
 In resting stage the nerve cell membrane is polarised due to different
charges present in and outside the membrane, this stage is called
resting potential.
 Inside the nerve cell membrane the the net charge is negative due to
presence of other negative charged ions

36. Immediately after repolarization occurs i.e
immediately after entry of Na+ ions into the
membrane the k+ ions flood out that returns
the initial state of the mebrane

39. Meninges
 Meninges surround the brain and spinal cord.
 They lie between skull-brain, and vertebral foramina-
spinal cord.
 There are three layer of meninges, named
1. Dura Matter ( Outer Matter )
2. Arachnoid Matter (Middle layer)
3. Pia Matter (Inner Layer)

41. Dura matter
 Cerebral dura matter consist of dense fibrous
tissue.
 Dura matter covers periosteum of skull and is
outer most layer of meninges .
 Dura matter provide a protective covering of
brain

42.  Dura matter forms a potential space anterior to
cerebram called falx cerebri
 Dura matter between cerebellar hemisphere forms falx
cerebelli
 Dura matter between cerebrum and cerebellum to form
tentorium cerebelli
 Spinal dura forms a sheath round spinal cord extending
from foramen magnum to second sacral vertibrae .
 It encloses filum terminale and fuses with periosteum
of coccyx .

43. Arachnoid matter
 It is separated from the dura matter by the subdural
space .
 They from the pia matter by the subaracnoid space
containing cerebrospinal fluid .
 It continues to the spinal cord and ends by merging
with the dura matter ; at the level of the 2nd sacral
vertebra.

44. Pia matter
 This is a delicate layer of connective tissue containing many minute
blood vessels .
 It adheres to the brain completely covering the convolutions and
dipping into each fissure .
 It continues downwards surrounding the spinal cord .
 Beyond the end of cord it continues as the filum terminale pierces
the arachnoid tube and goes on ,with the dura matter , to fuse with
the periosteum of the coccyx.

45. Ventricles
Ventricles are irregular shaped cavities
Lateral
ventricles
3rd ventricle 4th ventricle

47. Lateral ventricles
 There are two ventricles right and left.
 They are present within cerebral hemispheres, one on
each side of medial plane.
 Lateral ventricles are separated by septum lucidum.
 Lateral ventricles communicate with third ventricle via
interventricular foramina.

48. The third ventricle
 Third ventricle is situated below lateral ventricle
and between two parts of thalamus.
 It communicates with fourth ventricle via cerebral
aqueduct.

49. Fourth ventricle
 Fourth ventricle is a diamond shaped cavity
 It is situated below and behind the third ventricle between the
cerebellum and pons.
 It is continuous with central canal of spinal cord.
 It communicates with sub-arachanoid space by foramina
present in roof.
 CSF enters sub-arachanoid space by these foraminas.

50. CSF (Cerebrospinal Fluid)
 It is secreted by ependymal cells of choroid plexus
 CSF can enter Blood vessels through tiny diverticula
present in sub-arachnoid space when pressure of CSF
increases within the space
 But when blood pressure increases the arachnoid villi
collapses and prevents the blood entering the sub-
arachnoid space