Download Chapter 13 - Las Positas College

PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 1
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
The Central Nervous System

Central nervous system
 The brain and spinal cord

Directional terms unique to the CNS
 Rostral – toward the nose
 Caudal – toward the tail
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The Spinal Cord

Functions of the spinal cord
 Spinal nerves attach to it
 Provides two-way conduction pathway
 Major center for reflexes

Location of the spinal cord
 Runs through the vertebral canal
 Extends from the foramen magnum to the level of
the vertebra L1 or L2
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The Spinal Cord

Conus medullaris

Filum terminale

Cervical and lumbar enlargements

Cauda equina
 The inferior end of the spinal cord
 Long filament of connective tissue
 Attaches to the coccyx inferiorly
 Where nerves for upper and lower limbs arise
 Collection of spinal nerve roots
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The Spinal Cord
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Figure 13.2a
The Spinal Cord

Spinal cord segments
 Indicate the region of the spinal cord from which
spinal nerves emerge
 Designated by the spinal nerve that issues from it
 T1 is the region where the first thoracic nerve
emerges
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Spinal Cord Segments
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Figure 13.3
The Spinal Cord

Two deep grooves run the length of the cord
 Posterior median sulcus
 Anterior median fissure
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White Matter of the Spinal Cord

White matter
 Outer region of the spinal cord
 Composed of myelinated and unmyelinated axons
 Allow communication between spinal cord and
brain
 Fibers classified by type
 Ascending fibers
 Descending fibers
 Commisural fibers
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Gray Matter of the Spinal Cord and Spinal Roots

Shaped like the letter “H”
 Gray commissure – contains the central canal

Dorsal horns
 Consist of interneurons

Ventral and lateral horns
 Contain cell bodies of motor neurons
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Anatomy of the Spinal Cord
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Figure 13.4a
Anatomy of the Spinal Cord
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Figure 13.4b
Organization of the Gray Matter of the Spinal Cord

Gray matter
 Divided according to somatic and visceral regions
 SS – somatic sensory
 VS – visceral sensory
 VM – visceral motor
 SM – somatic motor
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Gray Matter of the Spinal Cord and Spinal Roots
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.5
Protection of the Spinal Cord

Protected by vertebrae, meninges, and CSF
 Meninges
 Dura mater – a single layer surrounding spinal cord
 Arachnoid mater – lies deep to the dura mater
 Pia mater – innermost layer
 Delicate layer of connective tissue
 Extends to the coccyx
 Denticulate ligaments – lateral extensions of
pia mater
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Cerebrospinal Fluid



Fills the hollow cavities of the brain and spinal
cord
Provides a liquid cushion for the spinal cord and
brain
Other functions
 Nourishes brain and spinal cord
 Removes wastes
 Carries chemical signals between parts of the CNS
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Diagram of Lumbar Puncture
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Figure 13.6
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 2
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
The Brain

Performs the most complex neural functions
 Intelligence
 Consciousness
 Memory
 Sensory-motor integration
 Involved in innervation of the head
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Embryonic Development of the Brain


Brain arises from rostral part of the neural tube
Three primary brain vesicles in four-week old
embryo
 Prosencephalon – the forebrain
 Mesencephalon – the midbrain
 Rhombencephalon – the hindbrain
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Embryonic Development of the Brain

Secondary brain vesicles
 Prosencephalon
 Divides into telencephalon and diencephalon
 Mesencephalon – remains undivided
 Rhombencephalon
 Divides into metencephalon and myelencephalon
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Embryonic Development of the Brain

Structures of the adult brain
 Develop from secondary brain vesicles
 Telencephalon the cerebral hemispheres
 Diencephalon thalamus, hypothalamus, and
epithalamus
 Metencephalon pons and cerebellum
 Myelencephalon medulla oblongata
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Embryonic Development of the Brain

Brain stem includes
 The midbrain, pons, and medulla oblongata

Ventricles
 Central cavity of the neural tube enlarges
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Embryonic Development of the Brain
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Figure 13.7a–e
Embryonic Development of the Brain

Brain grows rapidly, and changes occur in the
relative position of its parts
 Cerebral hemispheres envelop the diencephalon
and midbrain
 Wrinkling of the cerebral hemispheres
 More neurons fit within limited space
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Brain Development from Week 5 to Birth
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Figure 13.8a–d
Basic Parts and Organization of the Brain

Divided into four regions
 Cerebral hemispheres
 Diencephalon
 Brain stem
 Midbrain, pons, and medulla
 Cerebellum
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Basic Parts and Organization of the Brain
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Figure 13.9
Basic Parts and Organization of the Brain

Organization
 Centrally located gray matter
 Externally located white matter
 Additional layer of gray matter external to white
matter
 Due to groups of neurons migrating externally
 Cortex – outer layer of gray matter
 Formed from neuronal cell bodies
 Located in cerebrum and cerebellum
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Basic Parts and Organization of the Brain
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Figure 13.10
Ventricles of the Brain





Expansions of the brain’s central cavity
Filled with cerebrospinal fluid
Lined with ependymal cells
Continuous with each other
Continuous with the central canal of the spinal
cord
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Ventricles of the Brain

Lateral ventricles – located in cerebral
hemispheres
 Horseshoe-shaped from bending of the cerebral
hemispheres

Third ventricle – lies in diencephalon
 Connected with lateral ventricles by
interventricular foramen
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Ventricles of the Brain


Cerebral aqueduct – connects 3rd and 4th
ventricles
Fourth ventricle – lies in hindbrain
 Connects to the central canal of the spinal cord
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Ventricles of the Brain
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Figure 13.11a, b
The Brain Stem

Includes the
 Midbrain
 Pons
 Medulla oblongata
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The Brain Stem

Several general functions
 Produces automatic behaviors necessary for
survival
 Passageway for all fiber tracts running between the
cerebrum and spinal cord
 Heavily involved with the innervation of the face
and head
 10 of the 12 pairs of cranial nerves attach to it
 Which CN do NOT attach to brain stem?
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Ventral View of the Brain
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Figure 13.12
The Brain Stem – The Medulla Oblongata

Most caudal level of the brain stem
 Is continuous with the spinal cord
 Choroid plexus lies in the roof of the fourth
ventricle
 External landmarks of medulla
 Pyramids of the medulla
 Lie on its ventral surface
 Decussation of the pyramids
 Crossing over of motor tracts
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The Brain Stem – The Medulla Oblongata

External landmarks of medulla (continued)
 Inferior cerebellar peduncles
 Fiber tracts connecting medulla and cerebellum
 Olive (olive of the medulla)
 Contains inferior olivary nucleus
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The Brain Stem – The Medulla Oblongata

Cranial nerves VIII–XII attach to the medulla
 VIII – Vestibulocochlear
 IX – Glossopharyngeal nerve
 X – Vagus nerve
 XI – Accessory
 (Spinal Accessory – a branch of the vagus nerve)
 XII – Hypoglossal nerve
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The Brain Stem – Medulla Oblongata
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Figure 13.13a
The Brain Stem – Medulla Oblongata
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Figure 13.13b
The Brain Stem – The Medulla Oblongata

The core of the medulla contains
 Much of the reticular formation
 Nuclei influence autonomic functions
 Visceral centers of the reticular formation include
 Cardiac center
 Vasomotor center
 The medullary respiratory center
 Centers for hiccupping, sneezing, swallowing, and
coughing
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The Brain Stem – The Medulla Oblongata
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Table 13.1 (1 of 3)
The Brain Stem – The Medulla Oblongata
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Figure 13.13c
The Brain Stem – The Pons


A “bridge” between the midbrain and medulla
oblongata
Pons contains the nuclei of cranial nerves
 V – Trigeminal nerve
 VI – Abducens nerve
 VII – Facial nerve
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The Brain Stem – The Pons

The pons contains
 Motor tracts coming from the cerebral cortex
 Pontine nuclei
 Connect portions of the cerebral cortex and
cerebellum
 Send axons to cerebellum through the middle
cerebellar peduncles
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The Brain Stem – The Pons
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Figure 13.14b
The Brain Stem – The Pons
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Table 13.1 (2 of 3)
The Brain Stem – The Midbrain


Lies between the diencephalon and the pons
Cerebral aqueduct
 The central cavity of the midbrain

Cerebral peduncles located on the ventral surface
of the brain
 Contain pyramidal (corticospinal) tracts

Superior cerebellar peduncles
 Connect midbrain to the cerebellum
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The Brain Stem and Diencephalon
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Figure 13.13a
The Brain Stem and Diencephalon
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Figure 13.13b
The Brain Stem – The Midbrain

Periaqueductal gray
matter surrounds the
cerebral aqueduct

Involved in two
related functions
 Fright-and-flight

reaction
Mediates response
to visceral pain
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Figure 13.21
The Brain Stem – The Midbrain

Corpora quadrigemina (quad-ri-gemina)
 The largest nuclei
 Divided into the superior and inferior colliculi
 Superior colliculi – nuclei that act in visual
reflexes
 Inferior colliculi – nuclei that act in reflexive
response to sound
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The Brain Stem – Dorsal View
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Figure 13.13c
The Brain Stem – The Midbrain

Imbedded in the white matter of the midbrain
 Two pigmented nuclei
 Substantia nigra – neuronal cell bodies contain
melanin
 Functionally linked to the basal nuclei
 Red nucleus – lies deep to the substantia nigra
 Largest nucleus of the reticular formation
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The Cerebellum

Located dorsal to the pons and medulla
 Smoothes and coordinates body movements
 Helps maintain equilibrium
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The Cerebellum


Consists of two cerebellar hemispheres
Surface folded into ridges called folia
 Separated by fissures

Hemispheres each subdivided into
 Anterior lobe
 Posterior lobe
 Flocculonodular lobe (tiny)
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The Cerebellum
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Figure 13.15a
The Cerebellum

Composed of three regions
 Cortex – gray matter
 Arbor vitae
 Internal white matter
 Deep cerebellar nuclei – deeply situated gray
matter
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The Cerebellum

Cerebellum receives information from the cerebral
cortex
 On equilibrium
 On current movements of
 Limbs, neck, and trunk
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The Cerebellum – Cerebellar Peduncles

Thick tracts connecting the cerebellum to the brain
stem are
 Superior cerebellar peduncles
 Middle cerebellar peduncles
 Inferior cerebellar peduncles

Fibers to and from the cerebellum are ipsilateral
 Run to and from the same side of the body
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PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 3
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
The Diencephalon



Forms the center core of the forebrain
Surrounded by the cerebral hemispheres
Composed of three paired structures
 Thalamus
 Hypothalamus
 Epithalamus


Border the third ventricle
Primarily composed of gray matter
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The Diencephalon and Brainstem
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Figure 13.16
The Diencephalon – The Thalamus


Makes up 80% of the diencephalon
Contains approximately a dozen major nuclei
 Act as relay stations for incoming sensory message
 Every part of brain communicating with cerbral
cortex relays signals through thalamic nuclei!


Send axons to regions of the cerebral cortex
See figure 13.18b for nuclei
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The Diencephalon – The Thalamus

Afferent impulses converge on the thalamus
 Synapse in at least one of its nuclei


Is the “gateway” to the cerebral cortex
Nuclei organize and amplify or tone down signals
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The Diencephalon
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Figure 13.17a
The Diencephalon
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Figure 13.17b
Relationship of Thalamus to Cerebrum
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Figure 13.18a
The Thalamus (note nuclei)
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Figure 13.18b
The Diencephalon – The Hypothalamus




Lies between the optic chiasm and the
mammillary bodies
Pituitary gland projects inferiorly
Contains approximately a dozen nuclei
Main visceral control center of the body
 The master gland’s master!!
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The Diencephalon – The Hypothalamus

Functions include the following
 Control of the ANS
 Control of emotional responses
 Regulation of body temperature
 Regulation of hunger and thirst sensations
 Control of behavior
 Regulation of sleep-wake cycles
 Control of the endocrine system
 Formation of memory
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Nuclei of the Hypothalamus
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Figure 13.19
The Diencephalon – The Epithalamus



Forms part of the “roof” (top) of the third ventricle
Consists of a tiny group of nuclei
Includes the pineal gland (pineal body)
 Secretes the hormone melatonin
 Under influence of the hypothalamus
 Aids in control of circadian rhythm
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The Cerebral Hemispheres

Account for 83% of brain mass
 Fissures – deep grooves, which separate major
regions of the brain
 Transverse fissure – separates cerebrum and
cerebellum
 Longitudinal fissure – separates cerebral
hemispheres
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The Cerebral Hemispheres

Sulci
 Grooves on the surface of the cerebral hemispheres

Gyri
 Twisted ridges between sulci

Prominent gyri and sulci are similar in all people
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The Cerebral Hemispheres



Deeper sulci divide cerebrum into lobes
Lobes are named for the skull bones overlying
them
Central sulcus separates frontal and parietal lobes
 Bordered by two gyri
 Precentral gyrus
 Postcentral gyrus
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The Cerebral Hemispheres
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Figure 13.20a
The Cerebral Hemispheres

Parieto-occipital sulcus
 Separates the occipital from the parietal lobe

Lateral sulcus
 Separates temporal lobe from parietal and frontal
lobes

Insula – deep within the lateral sulcus
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The Cerebral Hemispheres
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Figure 13.20b, c
The Cerebral Hemispheres

Frontal section through forebrain
 Cerebral cortex
 Cerebral white matter
 Deep gray matter of the cerebrum (basal ganglia)
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The Cerebral Hemispheres
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Figure 13.21
The Cerebral Cortex


Home of our conscious mind
Enables us to
 Be aware of ourselves and our sensations
 Initiate and control voluntary movements
 Communicate, remember, and understand
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The Cerebral Cortex

Composed of gray matter
 Neuronal cell bodies, dendrites, and short axons



Folds in cortex – triples its size
Approximately 40% of brain’s mass
Brodmann areas
 52 structurally distinct areas
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The Cerebral Cortex

Functional regions
 Traditionally – studied brain-injured people and
animals
 New discoveries – PET and fMRI
 Regions of the cerebral cortex
 Perform distinct motor and sensory functions
 Memory and language spread over wide area
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Functional and Structural Areas of the Cerebral Cortex
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Figure 13.23a
Functional and Structural Areas of the Cerebral Cortex
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Figure 13.23b
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 4
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
The Cerebral Cortex

Three general kinds of functional areas
 Sensory areas
 Association areas
 Motor areas
PLAY
Rotatable Brain
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The Cerebral Cortex

Each of the major senses
 Has a specific brain region called a primary
sensory cortex
 Has an association area to process information
 These are multimodal association areas
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Functional and Structural Areas of the Cerebral Cortex
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Figure 13.23a
Functional and Structural Areas of the Cerebral Cortex
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Figure 13.23b
Sensory Areas

Cortical areas involved in conscious awareness of
sensation
 Located in
 Parietal lobes
 Temporal lobes
 Occipital lobes

PLAY
Distinct regions of each lobe interpret each of the
major senses
Rotatable Sectioned Brain
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Sensory Areas – Primary Somatosensory Cortex



Located along the postcentral gyrus
Involved with conscious awareness of general
somatic senses
Spatial discrimination
 Precisely locates a stimulus
 Certain regions are more adept at distinguishing
precise stimili
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Sensory Areas – Primary Somatosensory Cortex

Projection is contralateral
 Cerebral hemispheres
 Receive sensory input from the opposite side of the
body

Sensory homunculus
 A body map of the sensory cortex
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Sensory Areas – Primary Somatosensory Cortex
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Figure 13.24a
Sensory Areas – Somatosensory Association Cortex


Lies posterior to the primary somatosensory
cortex
Integrates different sensory inputs
 Touch
 Pressure

Draws upon stored memories of past sensory
experiences
 You are able to recognize keys or coins in your
pocket without looking at them
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Sensory Areas – Visual Areas

Primary visual cortex
 Location is deep within the calcarine sulcus
 On medial part of the occipital lobe
 Largest of all sensory areas
 Receives visual information that originates on the
retina
 Exhibits contralateral function
 First of a series of areas processing visual input
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Sensory Areas – Visual Areas

Visual association area
 Surrounds the primary visual area
 Continues the processing of visual information
 Analyzes color, form, and movement
 Complex visual processing extends into
 Temporal and parietal lobes
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Sensory Areas – Visual Areas

Visual association area
 Approximately 30 cortical areas have been
identified
 Visual information proceeds in two streams
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Sensory Areas – Visual Areas

Ventral stream
 Passes information into inferior part of the
temporal lobe
 Responsible for recognizing objects, words, and
faces

Dorsal stream
 Extends to the post-central gyrus
 Perceives information about spatial relationships

Ventral and dorsal streams
 The “what” and “where” pathways for vision
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The Ventral and Dorsal Streams
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Figure 13.25
Sensory Areas – Auditory Areas

Primary auditory cortex
 Function
 Conscious awareness of sound
 Sound waves excite receptors in the inner ear
 Impulses transmitted to primary auditory cortex
 Location
 Superior edge of the temporal lobe
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Sensory Areas – Auditory Areas

Auditory association area
 Lies posterior to the primary auditory cortex
 Permits evaluation of different sounds
 Lies in the center of Wernicke’s area
 Involved in recognizing and understanding speech
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Sensory Areas – Vestibular Cortex

Responsible for
 Conscious awareness of sense of balance

Located in the posterior part of the insula
 Deep to the lateral sulcus
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Sensory Areas – Gustatory Cortex

Function
 Involved in the conscious awareness of taste
stimuli

Location
 On the “roof” of the lateral sulcus
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Sensory Areas – Olfactory Cortex

Lies on the medial aspect of the cerebrum
 Located in a the piriform lobe

Olfactory nerves transmit impulses to the olfactory
cortex
 Provides conscious awareness of smells
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Sensory Areas – Olfactory Cortex


Part of the rhinencephalon – “nose brain”
Includes
 The piriform lobe, olfactory tracts, and olfactory
bulbs

Connects the brain to the limbic system
 Explains why smells trigger emotions

Involved with consciously identifying and
recalling specific smells
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Visceral Sensory Areas

Location
 Within the lateral sulcus
 On the insula lobe

Receives general sensory input
 Pain
 Pressure
 Hunger
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Multimodal Association Areas

Large areas of the cerebral cortex
 Receive sensory input from
 Multiple sensory modalities
 Sensory association areas
 Make associations between kinds of sensory
information
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Multimodal Association Areas

Three multimodal association areas
 Posterior association area
 Anterior association area
 Limbic association area
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Posterior Association Area

Located at interface of visual, auditory, and
somatosensory association areas
 Integrates sensory information into unified
perception
 Allows awareness of spatial location of body
 “Body sense”
 Related to language comprehension and speech
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Posterior Association Area

Multiple language areas in left cerebral cortex
 Wernicke’s area functions in
 Speech comprehension
 Coordination of auditory and visual aspects of
language
 Initiation of word artiucltion
 Recognition of sound sequences
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Posterior Association Area

Areas in right cerebral hemisphere act in
 Creative interpretation of words
 Emotional overtones of speech
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Anterior Association Area

A large region of the frontal lobe
 The prefrontal cortex




Receives information from posterior association
area
Integrates information with past experience
Initiates and plans motor movements
Has links to the limbic system
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Anterior Association Areas

More complex functions include all aspects of
 Thinking, perceiving, intentionally remembering
 Processing abstract ideas, reasoning, judgment
 Impulse control, mental flexibility, social skills
 Humor, empathy, conscience
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Anterior Association Area

Functional neuroimaging techniques
 Reveal functions of specific parts of the prefrontal
cortex

Anterior pole of frontal cortex
 Active in solving the most complex problems
 More complex problems, emotions, cognition at
anterior part of frontal lobe.
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Anterior Association Area

Additional functions
 Stores information for less than 30 seconds
 Three working memory areas
 Visual working memory
 Auditory working memory
 Executive area
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Limbic Association Areas

Located on medial side of frontal lobe
 Involved with memory and emotions
 Integrates sensory and motor behaviors
 Aids in the formation of memory
 Processes emotions
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Motor Areas – Premotor Cortex



Located anterior to the precentral gyrus
Controls more complex movements
Receives processed sensory information
 Visual, auditory, and general somatic sensory


Controls voluntary actions dependent on sensory
feedback
Involved in the planning of movements
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Motor Areas – Primary Motor Cortex

Controls motor functions
 Primary motor cortex (somatic motor area)
 Located in precentral gyrus (Brodmann area 4)

Pyramidal cells
 Large neurons of primary motor cortex
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Motor Areas – Primary Motor Cortex

Corticospinal tracts descend through brainstem
and spinal cord
 Axons signal motor neurons to control skilled
movements
 Contralateral
 Pyramidal axons cross over to opposite side of the
brain
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Motor Areas

Specific pyramidal cells control specific areas of
the body
 Face and hand muscles are controlled by many
pyramidal cells

Motor homunculus

Somatotopy
 Body map of the motor cortex
 Body is represented spatially in many parts of the
CNS
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Motor Areas
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.24b
Motor Areas – Frontal Eye Field

Lies anterior to the premotor cortex
 In Brodmann area 8

Controls voluntary movement of the eyes
 Especially when moving eyes to follow a moving
target
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Motor Areas – Broca’s Area

Located in left cerebral hemisphere
 Manages speech production
 Connected to language comprehension areas in
posterior association area

A corresponding region in the right cerebral
hemisphere
 Controls emotional overtones to spoken words
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Lateralization of Cortical Functioning

The two hemispheres control opposite sides of the
body
 Contralateral = opposite side

Hemispheres are specialized for different
cognitive functions
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Lateralization of Cortical Functioning

Left cerebral hemisphere – control over
 Language abilities, math, and logic

Right cerebral hemisphere – involved with
 Visual-spatial skills
 Reading facial expressions
 Intuition, emotion, artistic, and musical skills
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 5
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Cerebral White Matter

Different areas of the cerebral cortex
 Communicate with each other
 Communicate with the brainstem and spinal cord

Fibers communicating are
 Usually myelinated and bundled into tracts
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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
 Parts of Wernike’s and Broca’s areas are
connected by association fibers
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Cerebral White Matter
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.26a
Cerebral White Matter

Types of tracts (continued)
 Projection fibers – run vertically
 Descend from the cerebral cortex
 Ascend to the cortex from lower regions
 Corticospinal tracts begin with pyramidal cells
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Cerebral White Matter
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.26b
Projection Tracts

Internal capsule – projection fibers form a
compact bundle
 Passes between the thalamus and basal nuclei

Corona radiata – superior to the internal capsule
 Fibers run to and from the cerebral cortex
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Projection Tracts
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Figure 13.27a
Projection Tracts
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.27b
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 6
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Deep Gray Matter of the Cerebrum

Consists of
 Basal ganglia
 Involved in motor control
 Basal forebrain nuclei
 Associated with memory
 Claustrum
 A nucleus of unknown function

Amygdala
 Located in cerebrum but is considered part of the of
the limbic system
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Basal Ganglia


A group of nuclei deep within the cerebral white
matter
Formed from
 Caudate nucleus – arches over thalamus
 Putamen
 Globus pallidus
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Basal Ganglia

Complex neural calculators
 Cooperate with the cerebral cortex in controlling
movement


Receive input from many cortical areas
Substantia nigra also influences basal ganglia
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Basal Ganglia
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.26b
Basal Ganglia

Corpus striatum – combination of the lentiform
and caudate nuclei
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.27a
Basal Ganglia

Evidence shows that they
 Start, stop, and regulate intensity of voluntary
movements
 In some way estimate the passage of time
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Basal Forebrain Nuclei

Structures composing basal forebrain nuclei
 Septum
 Diagonal band of Broca
 Horizontal band of Broca
 Basal nucleus of Meynert
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Basal Forebrain Nuclei

Part of cholinergic system

Location

Functions related to
 That is, they synthesize and release acetylcholine
 Anterior and dorsal to hypothalamus
 Arousal
 Learning
 Memory
 Motor control
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Structures and Functions of the Cerebrum
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Table 13.4 (1 of 3)
Structures and Functions of the Cerebrum
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Table 13.4 (2 of 3)
Structures and Functions of the Cerebrum
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Table 13.4 (3 of 3)
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 7
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Functional Brain Systems

Networks of neurons functioning together
 Limbic system
 Spread widely in the forebrain
 The reticular formation
 Spans the brain stem
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Functional Brain Systems – The Limbic System

Location

Composed of

 Medial aspect of cerebral hemispheres
 Also within the diencephalon
 Septal nuclei, cingulate gyrus, and hippocampal
formation
 Part of the amygdala
The fornix and other tracts link the limbic system
together
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Functional Brain Systems – The Limbic System

The “emotional brain”
 Cingulate gyrus
 Allows us to shift between thoughts
 Interprets pain as unpleasant

Hippocampal formation
 Hippocampus and the parahippocampal gyrus
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Functional Brain Systems – The Reticular Formation


Runs through the central core of the medulla,
pons, and midbrain
Forms three columns
 Midline raphe nuclei
 Medial nuclear group
 Lateral nuclear group
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Functional Brain Systems – The Reticular Formation

Widespread connections
 Ideal for arousal of the brain as a whole

Reticular activating system (RAS)
 Maintains consciousness and alertness
 Functions in sleep and arousal from sleep
 Malfunctions in those with narcolepsy
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Functional Brain Systems – The Reticular Formation
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.29
Protection of the Brain

The brain is protected from injury by
 The skull
 Meninges
 Cerebrospinal fluid
 Blood-brain barrier
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Protection of the Brain – Meninges

Functions of meninges
 Cover and protect the CNS
 Enclose and protect the vessels that supply the
CNS
 Contain the cerebrospinal fluid
 Between pia and arachnoid maters
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Dura Mater


Strongest of the meninges
Composed of two layers
 Periosteal layer
 Meningeal layer
 Two layers are fused except to enclose the dural
sinuses
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The Dura Mater
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.30a
The Dura Mater


Largest sinus – the
superior sagittal
sinus
Dura mater
extends inward to
subdivide the
cranial cavity
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Figure 13.31
The Arachnoid Mater


Located beneath the dura mater
Arachnoid villi
 Project through the dura mater
 Allow CSF to pass into the dural blood sinuses
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The Pia Mater


Delicate connective tissue
Clings tightly to the surface of the brain
 Follows all convolutions of the cortex
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 8
The Central
Nervous
System
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Protection of the Brain – Cerebrospinal Fluid (CSF)

Formed in choroid plexuses in the brain
ventricles
 Choroid plexus is
 Located in all four ventricles
 Composed of ependymal cells and capillaries

Arises from blood
 500 ml/day
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Protection of the Brain – Cerebrospinal Fluid (CSF)
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.32a
Protection of the Brain – Cerebrospinal Fluid (CSF)
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.32b
Protection of the Brain – Blood-Brain Barrier

Prevents most blood-borne toxins from entering
the brain
 Impermeable capillaries

Not an absolute barrier
 Nutrients such as oxygen pass through
 Allows alcohol, nicotine, and anesthetics through
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Sensory and Motor Pathways in the CNS


Multineuron pathways connect brain and body
periphery
Pathways are composed of tracts
 Ascending pathways – carry information to more
rostral areas of the CNS
 Descending pathways – carry information to more
caudal regions of the CNS
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Major Fiber Tracts in White Matter of the Spinal Cord
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.34
Ascending Pathways


Conduct general somatic sensory impulses
Chains of neurons composed of
 First-, second-, and third-order neurons

Four main ascending pathways
 Dorsal column pathway
 Spinothalamic pathway
 Posterior spinocerebellar pathway
 Anterior spinocerebellar pathway
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Ascending Pathways
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Figure 13.35a, b
Descending Pathways

Most motor pathways
 Decussate at some point along their course
 Consist of a chain of two or three neurons
 Exhibit somatotopy
 Tracts arranged according to the body region they
supply

All pathways are paired
 One of each on each side of the body
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Descending Pathways


Deliver motor instructions from the brain to the
spinal cord
Divided into two groups
 Pyramidal (corticospinal) tracts
 Other motor pathways
 Tectospinal tracts
 Vestibulospinal tract
 Rubrospinal tract
 Reticulospinal tract
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Descending Pathways
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Figure 13.36a, b
Disorders of the Central Nervous System

Spinal cord damage
 Paralysis – loss of motor function
 Parasthesia – loss of sensation
 Paraplegia – injury to the spinal cord is between
T1 and L2
 Paralysis of the lower limbs
 Quadriplegia – injury to the spinal cord in the
cervical region
 Paralysis of all four limbs
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Disorders of the Central Nervous System

Brain dysfunction
 Degenerative brain diseases
 Cerebrovascular accident (stroke)
 Blockage or interruption of blood flow to a brain
region
 Alzheimer’s disease
 Progressive degenerative disease leading to
dementias
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Disorders of the Central Nervous System

Congenital malformations
 Hydrocephalus
 Neural tube defects
 Anencephaly – cerebrum and cerebellum are absent
 Spina bifida – absence of vertebral lamina
 Cerebral palsy – voluntary muscles are poorly
controlled
 Results from damage to the motor cortex
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Postnatal Changes in the Brain

Brain structures complete development at different
times
 Critical periods in learning
 Language
 Some development occurs into early 20s
 Decline with age attributed to changes
 In neural circuitry
 Amount of neurotransmitters being released
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings