The document provides information on the structure and function of the brain. It discusses: 1) The brain weighs around 1.4 kg on average and contains approximately 100 billion neurons, making it the most complex structure in the body. It is responsible for functions like thought, memory, and controlling bodily systems. 2) The brain is comprised of the cerebrum, cerebellum, and brainstem. The cerebrum controls functions like cognition and movement. The cerebellum regulates balance and motor coordination. The brainstem regulates vital functions like breathing and heart rate. 3) Key structures that support and protect the brain include the meninges and cerebrospinal fluid. The meninges are membranes surrounding

1. STRUCTURE AND
FUNCTION OF BRAIN
PRESENTED BY:
VISHAL.V.
14O0029
1ST
YEAR
SANKARA COLLEGE
OF OPTOMETRY
1

2. THE BRAIN
• The adult human brain weighs an average of 1.4
kg, or about 2 percent of the total body weight.
• Despite this relatively small mass, the brain
contains approximately 100 billion neurons.
• Functioning as a unit, these neurons make up the
most complex and highly organized structure on
Earth.
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3. THE BRAIN
• The brain is responsible for many of the qualities
that make each individual unique-thoughts,
feelings, emotions, talents, memories, and the
ability to process information.
• Much of the brain is dedicated to running the
body, the brain is responsible for maintaining
Homeostasis by controlling and integrating the
various systems that make up the body.
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4. • Brain
– Occupies 80% of cranium
– Comprised of 3 major structures
• Cerebrum
• Cerebellum
• Brainstem
– High metabolic rate
• Receives 15% of cardiac output
• Consumes 20% of body’s oxygen
• Requires constant circulation
– IF blood supply stops:
• Unconscious within 10 seconds
• Death in 4–6 minutes

5. Covering of brain
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Meninges
• membranes surrounding CNS
• protect CNS
• three layers
• dura mater – outer, tough
• arachnoid mater – thin, weblike
• pia mater – inner, very thin

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7. • Meninges
– Pia Mater
• Closest to brain and spinal cord
• Delicate tissue
• Covers all areas of brain and spinal cord
• Very vascular
– Supply superficial areas of brain
– Arachnoid Membrane
• “Spider-web like”
• Covers inner dura
• Suspends brain in cranial cavity
– Collagen and elastin fibers
• It is seperated from pia matter through sub-arachnoid space
– CSF
– Cushions brain
– Dura matter
– The outermost
– Thick,double layered membrane
– Lines the inner surface of cranial cavity

8. Meninges of the Spinal Cord
8

9. Blood-Brain Barrier
• Tight junctions prevent materials from diffusing across the
capillary wall.
• Astrocytes act as “gatekeepers” that permit materials to pass
to the neurons after leaving the capillaries.
• Is markedly reduced or missing in three distinct locations in
the CNS: the choroid plexus, hypothalamus, and pineal gland.

11. Ventricles
• interconnected cavities
within cerebral
hemispheres and brain
stem
• continuous with central
canal of spinal cord
• filled with cerebrospinal
fluid (CSF)
• lateral ventricles(1 & 2)
• third ventricle
• fourth ventricle
• cerebral aqueduct

12. Cerebrospinal Fluid
• secreted by choroid
plexus
• circulates in ventricles,
central canal of spinal
cord, and subarachnoid
space
• completely surrounds
brain and spinal cord
• clear liquid
• nutritive and protective
• helps maintain stable ion
concentrations in CNS

13. Cerebrospinal Fluid
CSF
• Made in choroid plexuses (roofs of ventricles)
– Filtration of plasma from capillaries through
ependymal cells (electrolytes, glucose)
• total volume 100-160 ml
• Cushions and nourishes brain
• Hydrocephalus: excessive accumulation

14. CSF circulation: through ventricles, median and lateral
apertures, subarachnoid space, arachnoid villi, and into the
blood of the superior sagittal sinus
CSF:
-Made in choroid plexus
-Drained through arachnoid villus

15. Hydrocephalus

16. Brain Development
Three Major Vesicles
1. Forebrain
2. Midbrain
3. Hindbrain

17. Brain Development

18. Brain
GROSS ANATOMY
• CEREBRUM
• CEREBELLUM
• DIENCEPHALON
• BRAIN STEM

19. Brain
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20. Structure of Cerebrum
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• corpus callosum
• connects cerebral
hemispheres
• convolutions
• bumps or gyri
• sulci
• grooves
• longitudinal fissure
• separates hemispheres
• transverse fissure
• separates cerebrum
from cerebellum

21. Organization of Brain Tissue
• Gray matter:
– motor neuron and interneuron cell bodies, dendrites, axon terminals
– unmyelinated axons.
• White matter:
– composed primarily of myelinated axons.
• External sheets of gray matter, called the cortex, cover the
surface of most of the adult brain (the cerebrum and the
cerebellum).

22. Organization of Brain Tissue
• White matter lies deep to the gray matter of the cortex.
• Within the masses of white matter:
– discrete innermost clusters of gray matter called cerebral nuclei (or
basal nuclei).
– are oval, spherical, or sometimes irregularly shaped clusters of neuron
cell bodies.

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24. Functional Regions of
Cerebral Cortex
Cerebral Cortex – thin layer of gray matter that
constitutes the outermost portion of cerebrum; contains
75% of all neurons in nervous system

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28. Lobes of Cerebral Hemispheres
• Frontal
• Parietal
• Temporal
• Occipital
• Insula

29. Frontal Lobe
The frontal lobe is the
area of the brain
responsible for higher
cognitive functions.
These include:
• Problem solving
• Spontaneity
• Memory
• Language
• Motivation
• Judgment
• Impulse control
• Social and sexual
behavior.

30. Temporal Lobe
• The temporal lobe
plays a role in
emotions, and is also
responsible for
smelling, tasting,
perception, memory,
understanding
music,
aggressiveness, and
sexual behavior.
• The temporal lobe
also contains the
language area of the
brain.

31. Parietal Lobe
• The parietal lobe
plays a role in our
sensations of
touch, smell, and
taste. It also
processes sensory
and spatial
awareness, and is
a key component
in eye-hand co-
ordination and arm
movement.

32. Occipital Lobe
The occipital lobe is
at the rear of the
brain and controls
vision and
recognition.

33. Limbic Lobe (or) insula
The limbic lobe is
located deep in the
brain, and makes up
the. limbic system

34. The Limbic System
A. Cingulate gyrus
B. Fornix
C. Anterior thalamic
nuclei
D. Hypothalamus
E. Amygdaloid
nucleus
F. Hippocampus
The limbic system is the
area of the brain that
regulates emotion and
memory. It directly
connects the lower and
higher brain functions.

35. Functions of the Cerebrum
• interpreting impulses
• initiating voluntary movements
• storing information as memory
• retrieving stored information
• reasoning
• seat of intelligence and personality

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37. Funcional area of cerebrum

38. Homunculus – “little man”
• Body map: human body spatially represented
– Where on cortex; upside down

39. Cerebral White Matter
• Types of tracts
– Commissures – composed of commissural fibers
• Allows communication between cerebral hemispheres
• Corpus callosum – the largest commissure
– Association fibers
• Connect different parts of the same hemisphere

41. Basal Nuclei
• masses of gray matter
• deep within cerebral
hemispheres
• caudate nucleus,
• putamen
• globuspallidus
produce dopamine

43. Basal nuclei functions
• Cooperate with the cerebral cortex in
controlling movements
• Receive input from many cortical areas
• Evidence shows that they:
– Start, stop, and regulate intensity of voluntary
movements
– In some way estimate the passage of time

44. Cerebellum
The cerebellum is
connected to the
brainstem, and is
the center for
body movement
and balance.

45. The Brainstem
• The brainstem is the most
primitive part of the brain
and controls the basic
functions of life: breathing,
heart rate, swallowing,
reflexes to sight or sound,
sweating, blood pressure,
sleep, and balance.
• The brainstem can be
divided into three major
sections:
• Mid brain
• Pons
• Medulla oblongata

46. Brainstem Divisions
Midbrain
Pons
Medulla Oblongata
10 of the 12 pairs of Cranial Nerves attached to it

47. The Cranial Nerves
I. Olfactory nerve
II. Optic nerve
III. Oculomotor nerve
IV. Trochlear nerve
V. Trigeminal nerve
VI. Abducens nerve
VII. Facial nerve
VIII. Vestibulocochlear
nerve
IX. Glossopharyngeal
nerve
X. Vagus nerve
XI. Accessory nerve
XII. Hypoglossal nerve

48. Anatomy and Physiology
of the Head
• Midbrain
–Upper portion of brainstem
• Structures:
THALAMUS
HYPOTHALAMUS

49. Thalamus
Thalamus means “inner room” in
Greek, as it sits deep in the brain at
the top of the brainstem.
The thalamus is called the gateway
to the cerebral cortex, as nearly all
sensory inputs pass through it to the
higher levels of the brain(cerebral
cortex)

50. Hypothalamus
The hypothalamus sits under the thalamus
at the top of the brainstem. Although the
hypothalamus is small, it controls many
critical bodily functions:
• Controls autonomic nervous system
• Center for emotional response and
behavior
• Regulates body temperature
• Regulates food intake
• Regulates water balance and thirst
• Controls sleep-wake cycles
• Controls endocrine system
The hypothalamus is
shaded blue. The
pituitary gland extends
from the hypothalamus.

51. The Pons
• The pons is the rounded
brainstem region
between the midbrain
and the medulla
oblongata. In fact, pons
means “bridge” in Latin
• Communication
interchange b/w
cerebellum,cerebrum,mid
brain & spinal cord.
• The pons is the origin of
several cranial nerves.

52. The Medulla Oblongata
 Most caudal level of the brain stem
• Choroid plexus lies in the roof of the fourth
ventricle
• Continuous with the spinal cord
• Cranial nerves VIII–XII attach to the medulla
• The medulla is primarily a control center
for vital involuntary reflexes such as
swallowing, vomiting, sneezing, coughing,
and regulation of cardiovascular and
respiratory activity.

54. Blood supply & venous drainage
• CNS Circulation
– Arterial
• Four Major Arteries
– 2 Internal carotid arteries
» From the common carotid
– 2 vertebral arteries
• Circle of Willis
– Internal carotids and vertebral arteries
– Encircle the base of the brain
– Venous
• Venous drainage occurs through bridging veins
• Bridge dural sinuses
• Drain into internal jugular veins

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56. Brain Functions
• Vision
• Taste
• Cognition
• Emotion
• Speech
• Language
• Hearing
• Motor Cortex
• Sensory Cortex
• Autonomic Functions

57. Vision
• The visual cortex
resides in the
occipital lobe of the
brain.
• Sensory impulses
travel from the eyes
via the optic nerve to
the visual cortex.
• Damage to the visual
cortex can result in
blindness.

58. Taste
• The gustatory
complex (green
circle) is the
part of the
sensory cortex
(purple area)
that is
responsible for
taste.

59. Cognition
• The prefrontal
cortex is
involved with
intellect,
complex
learning, and
personality.
• Injuries to the
front lobe can
cause mental
and
personality
changes.

60. Emotion
• Emotions are an
extremely complex brain
function. The emotional
core of the brain is the
limbic system . This is
where senses and
awareness are first
processed in the brain.
• Mood and personality
are mediated through the
prefrontal cortex. This
part of the brain is the
center of higher
cognitive and emotional
functions.
Prefrontal
cortex
Limbic system

61. Speech
• Broca’s area is
where we formulate
speech and the area
of the brain that
sends motor
instructions to the
motor cortex
• Injury to Broca’s area
can cause difficulty
in speaking. The
individual may know
what words he or
she wishes to speak,
but will be unable to
do so.
Broca’s Area

62. Language
Wernicke’s area is a
specialized portion of the
parietal lobe that
recognizes and
understands written and
spoken language.
Wernicke’s area
surrounds the auditory
association area.
Damage to this part of the
brain can result in
someone hearing speech,
but not understanding it.
Wernicke’s Area
Auditory Association
Area

63. Hearing
There are two
auditory areas of the
brain:
• The primary auditory
area (brown circle) is
what detects sounds
that are transmitted
from the ear. It is
located in the sensory
cortex.
• The auditory
association area
(purple circle) is the
part of the brain that
is used to recognize
the sounds as
speech, music, or
noise.

64. Motor Cortex
• The motor portion of the cerebrum
is illustrated here. The light red area
is the premotor cortex, which is
responsible for repetitive motions of
learned motor skills. The dark red
area is the primary motor area, and
is responsible for control of skeletal
muscles.
• Different areas of the brain are
associated with different parts of
the body.
• Injury to the motor cortex can result
in motor disturbance in the
associated body part.

65. Sensory Cortex
• The sensory portion of the
cerebrum is illustrated here.
• Different areas of the brain
are associated with different
parts of the body, as can be
seen below.
• Injury to the sensory cortex
can result in sensory
disturbance in the
associated body part.

66. Autonomic Functions
• The brainstem controls
the basic functions of
life. Damage to these
areas of the brain are
usually fatal:
• The pons plays a critical
role in respiration.
• The medulla oblongata is
responsible for
respiration and
cardiovascular functions.
Pons
Medulla Oblongata

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68. THANK YOU
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