Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid
 Blood-Brain Barrier
 Brain Dysfunction
Regions of the Brain
 Cerebrum
• Integration, speech, language,
emotion, memory, learning,
consciousness, behavior
 Diencephalon
• Sorting sensory input, homeostasis,
biological clock
 Brain stem
• Coordination of movement,
homeostasis, conduction of info to
higher centers
 Cerebellum
• Error checking of perceptual,
cognitive, and motor responses,
coordination, motor learning (handeye coordination, balance)
Cerebral
hemisphere
Diencephalon
(d) Birth
Cerebellum
Brain stem
• Midbrain
• Pons
• Medulla
oblongata
Figure 12.3d
Cerebral Hemispheres (2 Cerebra)
 Paired (left and right)
superior parts of the brain
 The surface is made of
ridges (gyri), grooves
(sulci), and deep
grooves (fissures)
 Fissures divide
cerebrum into lobes
• Frontal lobe
• Parietal lobe
• Occipital lobe
• Temporal lobe
Longitudinal
fissure
Transverse
cerebral fissure
Anterior
Longitudinal
fissure
Frontal lobe
Central sulcus
Cerebral veins
and arteries
covered by
arachnoid
mater
Parietal
lobe
Right cerebral
hemisphere
Occipital
lobe
Left cerebral
hemisphere
(c)
Posterior
Figure 12.6c
Functional Areas of the Cerebral Cortex
 The three types of functional areas are:
• Motor areas —control voluntary
movement
• Sensory areas —conscious awareness of
sensation
• Association areas —integrate diverse
information
 Conscious behavior involves the entire cortex
Motor Areas
 Primary (somatic) motor cortex
• Allows conscious control of precise,
skilled, voluntary movements
 Other motor areas include the Broca’s area
(speech) and the frontal eye field (vision)
Motor areas in red/orange
Central sulcus
Primary motor cortex
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
(a) Lateral view, left cerebral hemisphere
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Taste
Wernicke’s area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Vision
Hearing
Motor association cortex
Primary sensory cortex
Primary motor cortex
Sensory association cortex
Multimodal association cortex
Figure 12.8a
Sensory Areas
 Primary somatosensory cortex
 Somatosensory association cortex
 Visual areas
 Auditory areas
Motor and Sensory Areas of the Cerebral Cortex
Homunculous Diagrams
Motor areas in red/orange
Central sulcus
Primary motor cortex
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
Broca’s Area effects how words are
articulated in speech (left lob only)
(a) Lateral view, left cerebral hemisphere
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Taste
Wernicke’s area
(outlined by dashes) handles
articulation of unfamiliar words
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Vision
Hearing
Motor association cortex
Primary sensory cortex
Primary motor cortex
Sensory association cortex
Multimodal association cortex
Left cerebral hemisphere is the “language brain”
Right cerebral hemisphere is the “abstract, conceptual, and spatial brain”
Figure 12.8a
Motor and Sensory Areas of the Cerebral Cortex
Homunculous Diagrams
Projection
fibers
connect the
cortex to
lower brain
structures
and the
spinal cord,
eg. afferent
and efferent
tracts.
Association fibers (interneurons) connect
regions of the same hemisphere together
(white matter)
Commissural fibers connect the
Cerebral
two hemispheres to each other
hemisphere
Interthalamic
adhesion
(intermediate
mass of
thalamus)
Corpus
callosum
Posterior
commissure
Anterior
commissure
Pituitary gland
Medulla oblongata
Spinal cord
Neuron Cell Body Names and Locations
Clusters of cell bodies Bundles of nerve fibers
(neuronal processes)
CNS
Nuclei
Tracts
 White matter -dense
myelinated fibers
 Gray matter- unmyelinated
fibers and cell bodies
PNS
Ganglia
Nerves
(bundles of axons)
Layers of the Cerebrum
 Gray matter
• Outer layer
• Composed mostly of
neuron cell bodies
(nuclei)
 White matter
• Fiber tracts found deep
to the gray matter
• Example: corpus
callosum connects
hemispheres
Cortex of
gray matter
Inner gray
matter
Central cavity
Migratory
pattern of
neurons
Cerebrum
Cerebellum
Region of cerebellum
Outer white
matter
Gray matter
Central cavity
Inner gray matter
Outer white matter
Brain stem
Gray matter
Central cavity
Outer white matter
Spinal cord
Inner gray matter
Figure 12.4
Layers of the Cerebrum
 Basal nuclei – internal islands of gray matter (cell
bodies) where processing occurs to modify motor
instructions from primary motor cortex
•Influence muscular control
•Help regulate attention and cognition
•Regulate intensity of slow or stereotyped
movements
•Inhibit antagonistic and unnecessary
movements
Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid
 Blood-Brain Barrier
 Brain Dysfunction
Diencephalon: Three Parts
• Thalamus
 Surrounds the third ventricle
 The relay station for sensory
impulses (sense of expectation)
 Transfers impulses to the correct
part of the cortex for
localization and interpretation
• Hypothalamus
 Under the thalamus
 Important autonomic nervous
system center
o Helps regulate body
temperature
o Controls water balance
o Regulates metabolism
 An important part of the limbic
system (thirst, appetite, sex, pain,
pleasure)
 The pituitary gland is attached to
the hypothalamus
 Epithalamus
 Forms the roof of the third ventricle
 Houses the pineal body (an endocrine gland)
 Includes the choroid plexus – forms cerebrospinal fluid
Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid
 Blood-Brain Barrier
 Brain Dysfunction
Brain Stem
Routing for ascending and descending tracts and basal nuclei
for cranial nerves controlling breathing and blood pressure
Midbrain
• Contains cerebral aqueduct
connecting third and fourth
ventricles.
• Divides into 2 fiber tracts called
cerebral peducles
• Has posteriorly/dorsally
oriented four nuclei for vision
and hearing reflexes (corpora
quadrigemina)
Pons
• "Bridge" with nuclei to control
breathing and passage of fiber tracts
Medulla oblongata
• Fiber tract with nuclei
regulating heart rate, blood
pressure, breathing, swelling,
vomiting (autonomic functions)
Midbrain
Crus cerebri of
cerebral peduncles
(midbrain)
Thalamus
View (b)
Infundibulum
Pituitary gland
Superior colliculus
Inferior colliculus
Trochlear nerve (IV)
Trigeminal nerve (V)
Pons
Superior cerebellar peduncle
Middle cerebellar peduncle
Facial nerve (VII)
Abducens nerve (VI)
Glossopharyngeal nerve (IX)
Hypoglossal nerve (XII)
Inferior cerebellar peduncle
Vestibulocochlear nerve (VIII)
Olive
Thalamus
Vagus nerve (X)
Hypothalamus
Diencephalon
Midbrain
Accessory nerve (XI)
Pons
Brainstem
Medulla
oblongata
(b) Left lateral view
Figure 12.15b
Frontal lobe
Olfactory bulb
(synapse point of
cranial nerve I)
Optic chiasma
Optic nerve (II)
Optic tract
Mammillary body
Midbrain
Pons
Temporal lobe
Medulla
oblongata
Cerebellum
Spinal cord
Figure 12.14
Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid
 Blood-Brain Barrier
 Brain Dysfunction
Cerebellum: Two hemispheres
Control of balance, equilibrium, timing of muscle
activity, coordination: the "automatic pilot" or
coordinating center
Regions of the Brain
 Cerebrum (2 hemispheres)
• Integration, memory, learning
 Diencephalon
• Sorting signals and homeostasis,
day/night cycles, endocrine control
 Brain stem
• Heart rate, blood pressure,breathing,
conduction of messages
 Cerebellum
• Motor coordination and balance
Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid
 Blood-Brain Barrier
 Brain Dysfunction
Meninges: Dura mater, arachnoid, & pia mater
periosteal layer
meningeal layer
Subarachnoid
space with
CSF
Falx cerebri
dura mater = "tough mother"
Singular: menix
Plural: meninges
archnoid = "spidery"
pia mater = "delicate mother"
Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid and Ventricles
 Blood-Brain Barrier
 Brain Dysfunction
Cerebrospinal Fluid (CSF)
 Composition
• Watery solution with constant volumne
• Less protein and different ion concentrations than plasma
 Functions
• Gives buoyancy to the CNS organs
• Protects the CNS from blows and other trauma
• Nourishes the brain and carries chemical signals
 Production at choroid plexi
• Produce CSF at a constant rate hanging from the roof of
each ventricle
• Ependymal cells use ion pumps to control the composition
of the CSF and help cleanse CSF by removing wastes
Ventricles of the Brain
Lateral ventricle
Septum pellucidum
Anterior horn
Inferior
horn
Lateral
aperture
Interventricular
foramen
Third ventricle
Inferior horn
Cerebral aqueduct
Fourth ventricle
Central canal
(a) Anterior view
(b) Left lateral
Posterior
horn
Median
aperture
Lateral
aperture
view
Figure 12.5
Ventricles and Location of the Cerebrospinal Fluid
Interventricular foramen
Medial aperture (of
Magendie) and lateral
apertures to
subarachnoid space
Cerebralspinal fluid flow movie
Blood Brain Barrier
 Includes the least permeable
capillaries of the body
 Excludes many potentially
harmful substances
 Useless against some
substances
• Fats and fat soluble
molecules
• Respiratory gases
• Alcohol
• Nicotine
• Anesthesia
Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid
 Blood-Brain Barrier
 Brain Dysfunction
The Twelve Cranial Nerves (I-V)
I Olfactory nerve – purely sensory for smell; ask
patient to identify oil of cloves and vanilla
II Optic nerve – purely sensory for vision;
observe eye, test patient with eye chart
III Oculomotor nerve – mostly motor fibers to
eye muscles, some proprioreceptive afferents;
examine pupil size and reflex, ability to follow
objects with the eye
IV Trochlear – mostly motor fibers to extrinsic
eye muscles; test patient’s ability to follow
objects with eye
V Trigeminal nerve – 3 divisions:
•
Opthalmic (tested by corneal reflex)
carrying sensory for skin of anterior
scalp, eyelid, nose
•
Maxillary (tested with pain, touch
temperature using safety pin) carrying
sensory from nasal cavity, palate, upper
lip, cheek
•
Mandibular (test by teeth clenching,
move jaw) carrying sensory from lower
teeth, masseter, temporalis
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The Twelve Cranial Nerves (Vi-XIII)
VI Abducens nerve – motor fibers to eye muscles
(lateral rectus); test by having patient follow
object side-to-side
VII Facial nerve – sensory for taste; motor fibers
to the face (test with ability to taste sweet salt,
sour, bitter and close eyes, smile, whistle, make
tears); five major branches: temporal,
zygomatic, buccal, mandibular, cervical
VIII Vestibulocochlear nerve – sensory for
balance (semicircular canals) and hearing; test
with air and bone conduction with tuning fork
IX Glossopharyngeal nerve – sensory for taste and
touch, pressure, pain from posterior tongue;
motor fibers to the swallowing muscles in
pharynx; test for gag and swallowing reflex,
cough, taste, uvula position
X Vagus nerves – sensory (including aortic arch
baroreceptors, respiration) and motor fibers for
pharynx, larynx, and viscera (heart rate,
breathing, digestive activity); test by gag,
swallowing reflexes
XI Accessory nerve – mostly motor fibers to neck
and upper back (trapezius, sternocleidomastoid);
test for head rotation strength and shrugging
against resistance
XII Hypoglossal nerve – mostly motor fibers to
tongue allowing food manipulation; test by
tongue protraction and retraction)
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Diseases of the Brain
 Parkinson's Disease
 Degeneration of the dopaminereleasing neurons of the substantia
nigra: causes tremors, loss of coordination
 Huntington's Chorea
 A fatal hereditary disorder caused by
accumulation of the protein huntingtin that
leads to degeneration of the basal nuclei
and cerebral cortex: causes jerky
movements
 Alzheimer's Disease
 A progressive degenerative disease of
the brain that results in dementia
Traumatic Brain Injuries
 Concussion
 Cerebral edema
 Contusion
edema
blood at
arrows
7 month old baby having siezures
(probably a victim of child abuse)
Cerebrovascular Accident (CVA): Stroke
• Blood circulation is blocked and brain
tissue dies, e.g., blockage of a
cerebral artery by a blood clot
• Typically leads to hemiplegia, or
sensory and speed deficits
Computed tomography (CT) scan showing
hemhorrage in right thalamus
Transient ischemic attacks (TIAs)
Temporary episodes of reversible cerebral ischemia
Central Nervous System: The Brain
• Anatomy of the Brain
 Cerebral Hemispheres
 Diencephalon
 Brain Stem
 Cerebellum
• Protection of the CNS
 Meninges
 Cerebrospinal Fluid
 Blood-Brain Barrier
 Brain Dysfunction