Lect. 1 Organization of the Nervous System 54

8/3/2019 Lect. 1 Organization of the Nervous System 54

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Functional Organization of

Nervous System

รายวชิาระบบร่างกายมนุษย์ ระบบประสาท กบ202

ดร.นพพร จงกมลวิวัฒน์

คณะสหเวชศาสตร์มหาวิทยาลัยศรีนครินทรวโิรฒ

[email protected]

mailto:[email protected]




• Function and organization of nervous

system

• Nervous system components

• Development of nervous system

• Circulation and Cerebrospinal Fluid (CSF)

About this Chapter


http://www.feebleminds-gifs.com/skeltw2.gif



Planes and Sections

• Transverse (cross-sectional)or horizontal plane

– divides the body or an organinto upper (superior) or lower

(inferior) portions• Frontal or coronal plane

– divides the body or an organinto front (anterior) and back

(posterior) portions• Sagittal plane

– divides the body or an organinto left and right sides



Planes and Sections of the Brain(3-D anatomical relationships revealed)

• Transverse Plane(Horizontal)

• Frontal Plane(Coronal)

• Sagittal Plane



Planes and Sections of the Brain

Inferior (below)

Superior (above)

Anterior(front)

Posterior(back)



Organization of the Nervous System

XL



Functions of the Nervous System

Motor output - A response to integrated stimuli

The response activates muscles or glands

Sensory input - Gathering information

To monitor changes occurring inside and outside the

body

Integrationto process and interpret

sensory input and decide if

action is needed.



Structural Classification of theNervous System

CNS

PNS



Sensory (afferent) division

Nerve fibers that carry information

to the central nervous system

Motor (efferent) divisionNerve fibers that carry impulses away

from the central nervous system




Regions of the Brain

The Central Nervous System

Cerebral hemispheres

Diencephalon

Brain stem

Cerebellum

‘Telencephalon’



Cerebral Hemispheres (Cerebrum)

Paired (left and right)

superior parts of the

brain

Include more than

half of the brain mass

The surface is made

of ridges (gyri ) and

grooves (sulci)



Layers of the Cerebrum

Gray matter

Outer layer, Composedmostly of neuron cellbodies

White matterFiber tracts inside thegray matter (corpuscallosum)

Basal nuclei Internal islandsof gray

matter



Layers of the Cerebrum



Lobes of the Cerebrum

Fissures (deep grooves) divide the cerebrum into lobes

Surface lobes of the cerebrum

Frontal lobe

Parietal lobe

Occipital lobe

Temporal lobe



Lobes of the Cerebrum

XL



Specialized Area of the Cerebrum

XL



Broadmann’s Area

XL



Sensory and Motor Areas of theCerebral Cortex



‘Homunculus’



‘Basal Nuclei’ ‘Limbic System’

Basal Ganglia




The Limbic System




Functions of the Cerebrum

– Conscious thought

– Intellectual activity

– Memory

– Origin of complex patterns of movement




Functions of the Cerebral Cortex

– Hemispheres serve opposite body sides

– Primary motor cortex

• Directs voluntary movement – Primary sensory cortex

• Receives somatic sensation (touch, pain, pressure,

temperature) – Association areas

• Interpret sensation

• Coordinate movement



The Central Nervous SystemThe Brain

XL




XL



Diencephalon



Diencephalon

Brain stem

Cerebellum



Diencephalon

Sits on top of the brain stem

Enclosed by the cerebral hemispheres

Made of three parts

Thalamus

Hypothalamus

Epithalamus

Di h l



Thalamus Surrounds the third ventricle

The relay station for sensory impulses

Transfers impulses to the correct part of the cortex forlocalization and interpretation

Coordinate voluntary and involuntary motor behavior

Diencephalon

Di h l



Hypothalamus

An important part of the limbic system (emotions)

The pituitary gland is attached to the hypothalamus

Diencephalon

Under the thalamus Important autonomic nervous system center

Helps regulate body temperature

Controls water balance

Regulates metabolism

Di h l



Epithalamus

Forms the roof of the third ventricle Houses the pineal body (an endocrine gland)

Includes the choroid plexus – forms cerebrospinal fluid

Diencephalon



Brain Stem



Diencephalon

Brain stem

Cerebellum

Brain Stem



Brain Stem Parts of the brain stem

Midbrain ‘Mesencephalon’

Pons ‘Metencephalon’

Medulla oblongata ‘Myelencephalon’

Brain Stem



Midbrain

Slide 7.39

Mostly composed of tracts of nerve fibers

Reflex & Relay center for vision and hearing

Cerebral aqueduct – 3 rd -4 th ventricles

Brain Stem

Brain Stem



Pons The bulging center part of the brain stem

Mostly composed of fiber tracts

Includes nuclei involved in the control of breathing

Brain Stem

Brain Stem



Medulla Oblongata The lowest part of the brain stem

Merges into the spinal cord Includes important fiber tracts

Contains important control centers

Heart rate

Blood pressure

Breathing

Swallowing

Vomiting

Brain Stem



The Diencephalon and Brain Stem

XL



The Diencephalon and Brain Stem

Cranial Nerve

XL



Cerebellum



Diencephalon

Brain stem

Cerebellum



Cerebellum Two hemispheres with convoluted surfaces

Provides involuntary coordination of body movements Stores patterns of movement, Skills

Fine tunes most movements

Control postural muscles, balance (Vestibular)

Th C t l N S t




• Relays information to/frombrain

• Processes some informationon its own

• Divided into 31 segments • Each segment has a pair of:

Dorsal root ganglia

Dorsal roots

Ventral roots• Gray matter appears as

horns

• White matter organized into

columns

Spinal Cord Basics• Cervical

• Thoracic

• Lumbar

• Sacral

S i l C d O i i



Gray matter: mostly cell bodies

Spinal reflex integrating centerWhite matter:

Bundles of myelinated axons

-Ascending tracts: sensory

-Descending tracts: motor

Spinal Cord Organization

S i l C d O i i




XL



The Spinal Reflex Arc

Reflex – rapid, predictable, and involuntary responses tostimuli

Reflex arc – direct route from a sensory neuron, to aninterneuron, to an effector



The Spinal Reflex Arc

Ner o s S stem & Skeletal S stem



Nervous System & Skeletal System



Development of the CNS

Development of the CNS



Development of the CNSThree "germ layers“

Ectoderm Mesoderm Endoderm

N S t D l t



• Neural plate to neural tube

• Neural crest –PNS• Anterior forms brain

Forebrain

Midbrain

Hindbrain

• Hollow ventricles

• Spinal cord

Nervous System Development

Expansion of Brain



Expansion of Brain

XL

E i f B i



Expansion of Brain

Forebrain

• Telencephalon

• DiencephalonMidbrain

• remains justmidbrain

Hindbrain• Pons,

Cerebellum

• Medulla

Between 4 weeks and 9 months the



Between 4 weeks and 9 months thebrain undergoes rapid development

E i f B i



Expansion of Brain

Six Stages of Nervous System Development



Six Stages of Nervous System Development

Post natal brain development



• At birth the brain weighs 25% of the full adult brain

• By the age of 6 it increases to 95%i. Increase is due to myelination

ii. Proliferation of glial cells

iii. Last wave of neurogenesis *

iv. Maturation of neurons

v. Increase in synaptic connectivity

Post-natal brain development



Vasculature & Ventricle

Cerebral Blood Supply



The most metabolically active organs in the body, receiving17% of the total cardiac output and about 20% of the oxygen

available in the body.

Cerebral Blood Supply

Principle Brain Arteries



Principle Brain Arteries

80%

20%

XL



Circle of Willis

Brain Vascular Territory




XL




Spinal Cord

Arterial Supply

XL



Ventricles and Cerebrospinal Fluid

Cerebrospinal Fluid



Cerebrospinal Fluid

• Clear liquid fills ventricles andcanals & bathes its externalsurface (in subarachnoid space)

• Brain produces & absorbs about500 ml/day

- Produced by ependymal cellslining the ventricles

- Filtration of blood throughchoroid plexus

• Functions

- Buoyancy- Protection

- Chemical stability

- Nutrient supply



The Ventricles of the Brain

XL

Flow of Cerebrospinal Fluid



p

XL

Meninges



Meninges

Pia materArachnoid mater

Dura mater

Peripheral Nervous System



Peripheral Nervous System

Nerves and ganglia outside the central nervous system

Nerve = bundle of neuron fibers

Neuron fibers are bundled by connective tissue

Structure of a Nerve



Structure of a Nerve

Endoneurium surrounds

each fiber

Groups of fibers are bound

into fascicles by perineurium

Fascicles are bound together

by epineurium

Classification of Nerves



Classification of Nerves

Mixed nerves – both sensory and motor fibers

Afferent (sensory) nerves – carry impulses toward the

CNS

Efferent (motor) nerves – carry impulses away from the

CNS

Classification by size and myelination, Aa, Ab, C



End of First Chapter LoL

Q ti ?

Lect. 1 Organization of the Nervous System 54

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