2011年春季學(xué)期期末教學(xué)水平測(cè)試試卷-基礎(chǔ)科學(xué)-

Functional

Human

Physiologyfor

the

Exercise

and

Sport

SciencesThe

Nervous

SystemJennifer

L.

Doherty,

MS,

ATCDepartment

of

Health,

Physical

Education,

andRecreationFlorida

International

UniversityOverview

of

the

Nervous

SystemTwo

major

anatomical

divisions?

The

central

nervous

system(CNS)BrainSpinal

Cord?

The

peripheral

nervous

system

(PNS)Afferent

DivisionEfferent

Division?

Somatic

Nervous

System?

Autonomic

Nervous

SystemFunctional

Divisions

of

the

PNS?

Afferent =

SensorySomatic

sensoryVisceral

sensory?

Efferent

=

MotorSomatic

motorVisceral

motorOverview

of

the

Nervous

System

Divisions

of

the

PNS

according

to

type

ofcontrol?

Somatic

nervous

systemVoluntary?

Autonomic

nervous

systemInvoluntary

Further

divided

according

to

the

overall

effect

onthe

organs:?

Sympathetic

division

=

“Fight

or

Flight”?

Parasympathetic

division

=

“Rest

and

Repair”O(jiān)verview

of

the

Nervous

SystemFunctions

of

the

Nervous

SystemCollecting

information?

Peripheral

Nervous

SystemSensory

or

afferent

inputEvaluation

and

decision

making?

Central

Nervous

System?

Integration

and

comparison

to:Homeostatic

rangesPrevious

or

learned

experiencesElicits

responses?

Peripheral

Nervous

SystemMotor

or

efferent

outputGeneral

Anatomy

of

the

CNSGlial

Cells?

Supporting

cells

for

neurons

in

the

CNS?

5

typesOligodendrocytes

=

form

myelin

in

the

CNSSchwann

Cells

=

form

myelin

in

the

PNSMicroglia

Cells

=

macrophages

of

the

CNSEpendymal

Cells

=

line

cerebral

ventriclesAstrocytes

=

develop

neuronal

connectionsGeneral

Anatomy

of

the

CNSCranium/Skull?

Protects

this

soft

tissue

of

the

brainVertebral

Column?

Protects

the

spinal

cordMeninges?

Connective

tissue

membranes

that

separate

thesoft

tissue

of

the

CNS

from

surrounding

boneDura

MaterArachnoid

materPia

MaterGeneral

Anatomy

of

the

CNSCerebrospinal

Fluid

(CSF)?

Clear,

watery

fluid

that

bathes

the

CNS?

Acts

as

a

shock

absorber

to

prevent

injury?

Provides

nutrients

to

glial

cells?

Removes

waste

products?

Maintains

normal

ionic

concentrationssurrounding

neuronsGeneral

Anatomy

of

the

CNS

The

CNS

requires

an

abundant

bloodsupply

due

to

the

high

metabolic

rate

ofneuronal

tissue?

Brain

accounts

for

20%

of

all

O2

used?

Brain

accounts

for

50%

of

all

glucose

usedBlood-Brain

Barrier?

A

physical

barrier

between

the

CSF

andblood?

This

semi-permeable

membrane

functions

toprotect

the

environment

surrounding

the

neuronsin

the

CNSGeneral

Anatomy

of

the

CNSClassification

of

Neurons?

Classified

according

to

the

direction

that

the

nerveimpulse

travels

in

relation

to

the

central

nervous

system.Sensory

/

Afferent

Neurons?

Receptors:

located

in

the

peripherysensitive

to

changes

inside

or

outside

of

the

body?

Nerve

impulses:

travel

toward

the

CNSInterneurons?

Also

call

Association

/

Internuncialneurons?

Function:

link

between

afferent

and

efferentneuronsRelay

information

from

one

part

of

the

CNS

toanother

for

processing,

interpreting,

and

eliciting

aresponseMotor

/

Efferent

Neurons?

Nerve

impulses:

travel

away

from

the

CNS

towardeffector

organsGeneral

Anatomy

of

the

CNSGeneral

Anatomy

of

the

CNSGray

Matter?

Areas

of

the

CNS

consisting

primarily

of:Cell

bodiesDendritesAxon

terminals?

Area

where

synaptic

transmission

and

neural

integrationoccursWhite

Matter?

Areas

in

the

CNS

consisting

primarily

of

myelinatedaxons

Function

to

rapidly

transmit

action

potentials

over

relativelylong

distancesThe

Spinal

CordCylinder

of

nervous

tissue?

Continuous

with

the

lower

portion

of

the

brainBranches

into

31

pairs

of

spinal

nerves?

Cervical

nerves

(C1

–

C8)?

Thoracic

nerves

(T1

–

T12)?

Lumbar

nerves

(L1

–

L5)?

Sacral

nerves

(S1

–

S5)?

Coccygeal

nerve

(C0)The

Spinal

Cord

Gray

matter:

concentrated

in

the

butterfly-shaped

interior

region

of

the

spinal

cordVentral

Horn?

Contains

Efferent

NeuronsInterneuronsCell

bodiesDendriteDorsal

Horn?

Contains

Afferent

NeuronsAxon

terminalsThe

Spinal

CordAfferent

Nerve

Fibers?

Cell

bodies

are

located

outside

the

spinal

cord

inclusters

called

dorsal

root

ganglia?

These

fibers

form

the

dorsal

rootsEfferent

Nerve

Fibers?

Cell

bodies

are

located

in

the

spinal

cord?

These

fibers

for

the

ventral

rootsThe

Spinal

CordSpinal

Nerves?

Contain

both

afferent

and

efferent

axons?

Joining

of

the

dorsal

root

and

the

ventral

root?

Called

Mixed

NervesSpinal

Cord

White

Matter:

consists

of

Tracts

providingcommunication

betweenDifferent

levels

of

the

spinal

cord,

orThe

brain

and

various

levels

of

the

spinal

cordAscending

Tracts?

Transmit

information

from

the

spinal

cord

to

thebrainDescending

Tracts?

Transmit

information

from

the

brain

to

the

spinalcordThe

BrainForebrain?

Largest

and

most

superior

portion

of

the

brain?

Divided

into

right

and

left

hemispheres?

Consists

of

the

Cerebrum

and

DiencephalonCerebellum?

Located

inferior

to

the

forebrain?

Functions

include

motor

coordination,

balance,

andfeedback

systemsBrainstem?

Connects

the

forebrain

and

cerebellum

to

the

spinal

cord?

Consists

of

the

Midbrain,

Pons,

and

Medulla

OblongataThe

Brain

–

Cerebrum

(Forebrain)Cerebral

Cortex?

Thin,

highly

convoluted

layer

gray

matter?

Responsible

for

conscious

initiation

of

voluntarymovementsRegionsof

the

Cerebral

Cortex?

Frontal

Lobes?

Parietal

Lobes?

Temporal

Lobes?

Occipital

LobeThe

Brain

–

Cerebrum

(Forebrain):Areas

of

Specialized

FunctionPrimary

Somatosensory

Cortex?

Involved

in

processing

somatic

sensoryinformation

associated

with:

Somesthetic

sensations

suchas

touch,

temperatureand

pain

perception

Proprioception

which

is

theawarenessof

muscletension,

joint

position,

and

limb

positionPrimary

Motor

Cortex?

Initiates

voluntary

movementThe

Brain

–

Cerebrum

(Forebrain)The

cerebral

cortex

is

topographically

organized?

Areas

may

be

mapped

according

to

function?

Called

somatotopic

organizationMotor

and

Sensory

Homunculi?

Map

of

the

cerebral

cortex

corresponding

to

the

part

ofthe

body

served

by

a

particular

region?

The

size

of

the

body

part

on

the

homunculus

isproportional

to

the

amount

of

brain

dedicated

to

that

bodypart

For

Example,

the

hand

is

very

large

on

both

the

sensory

andmotor

homunculus

because

it

has

many

sensory

receptorsand

requires

very

fine

motor

control.The

Brain

–

Cerebrum

(Forebrain)Subcortical

Nuclei?

Regions

of

gray

matter

within

the

cerebrumIncludes

the

Basal

Nuclei

(Basal

Ganglia)?

Masses

of

gray

matter

scattered

deep

within

thecerebral

hemispheres?

Components

of

the

basal

nuclei

include:The

caudate

nucleusThe

putamenThe

globus

pallidus?

Important

role

in

modifying

movementThe

Brain

-

Basal

Nuclei

Normally

inhibit

motor

function

therebycontrolling

muscle

activityReceive

input

from:?

The

entire

cerebral

cortex?

Othersubcortical

nuclei

Such

as

the

subthalamic

nucleus

of

the

diencephalon,substantia

nigra,

and

the

red

nucleus

No

direct

connections

with

the

motorpathways?

Send

information

to

the

Primary

Motor

Cortex

through

thethalamusComplex

role

in

motor

control?

Important

in

starting,

stopping,

and

monitoringmovements

executed

by

the

primary

motor

cortex?

It

is

particularly

involved

in

slow,

sustained,

orstereotyped

movementsExamples:

arm

swing

during

gait,

riding

a

bicycle,

or

eatingInhibit

antagonistic

(unnecessary)

movements?

Enhances

the

ability

to

perform

several

tasks

at

onceImpairment

results

in:?

Disturbances

in

muscle

tone

and

posture?

Tremors?

Abnormally

slow

movementThe

Brain

-

Basal

NucleiThe

Brain

–

Diencephalon(Forebrain)The

diencephalon

includes

two

structures:ThalamusHypothalamus

Referred

to

as

the

“gateway”

to

thecerebral

cortex

Most

afferent

neurons

synapse

with

at

leastone

of

the

thalamic

nuclei

The

major

relay

station

for

all

sensory

input(except

smell)?

A

relay

station

for

impulses

that

regulate

emotion?

Also

a

relay

station

for

motor

impulses

from

thecerebellum

and

basal

gangliaThalamusConsists

of

many

separate

groups

of

nuclei?

Each

receiving

a

certain

kind

of

information?

Information

is

sent

from

the

thalamic

nuclei

to

aparticular

region

of

the

cortexNuclei

of

the

Thalamus?

Ventral

Posterolateral

Nucleus?

Ventral

Lateral

Nucleus?

Medial

and

Lateral

Geniculate

BodiesThalamusThalamusThe

Ventral

Posterolateral

Nucleus?

Receivessomatic

sensory

information

(touch,

pressure,

pain)?

Relays

information

to

the

somatosensory

region

of

the

cerebralcortexThe

Ventral

Lateral

Nucleus?

Receivesmotor

information

from

the

basal

nuclei

andcerebellum?

Relays

information

to

the

motor

region

of

the

cerebral

cortexThe

Medial

andLateral

Geniculate

Bodies?

The

medial

geniculate

body

sends

auditory

information

from

theauditory

receptors

to

the

auditory

region

of

the

cerebral

cortex?

The

lateral

geniculate

body

sends

visual

information

to

theoccipital

region

of

the

cerebral

cortex

Located

inferior

to

the

thalamus

and

superiorto

the

brain

stem

It

is

interconnected

to

the

cerebral

cortex,thalamus,

and

other

parts

of

the

brain

stem

It

consists

of

a

collection

of

many

differentnuclei.?

The

Supraoptic

Nucleus?

The

Paraventricular

Nucleus?

The

Preoptic

Nucleus?

The

Ventromedial

NucleusHypothalamus

The

hypothalamus

has

many

roles

in

regulatinghomeostasis

It

senses

the

chemical

and

thermal

qualities

of

thebloodIt

is

involved

in:?

Regulation

of

heart

rate

and

arterial

blood

pressure;?

Control

of

movements

and

glandular

secretions

of

thestomach

and

intestines;?

Regulation

of

respiratory

rate;?

Regulation

of

water

and

electrolyte

balance;

and?

Control

of

hunger

and

regulation

ofbodyweight.Hypothalamus

A

diverse

collection

of

closely

associated

cerebralcortical

regions?

Encircle

the

upper

part

of

the

brain

stem

lending

is

name,limbus

(refers

to

ring)The

structures

of

the

limbic

system

include:?

The

hippocampus?

The

mammillary

bodies

of

the

diencephalon?

The

hypothalamus?

The

anterior

nucleus

of

the

thalamus?

The

amygdaloid

body?

Several

gyri

and

fiber

tracts

(fornix)

that

have

not

yetbeen

specifically

identifiedLimbic

SystemControls

the

emotional

aspects

of

behaviorConnected

to

the

cerebral

cortex

and

brain

stem?

Allows

for

perception

and

response

to

a

wide

variety

ofstimuli

Communicates

with

the

prefrontal

lobes

to

elicit

arelationship

between

feelings

and

thoughts.?

This

explains

why

emotions

sometimes

override

thoughtsand

why

reason

can

override

emotion

when

an

emotionalresponse

would

be

inappropriate.

Part

of

the

system,

the

hippocampus

and

theamygdaloid

body

are

involved

in

memoryLimbic

SystemThe

Brain

-

Cerebellum

Located

inferior

to

the

forebrain

and

posterioto

the

brainstemFunctions:?

Coordination

of

muscular

activitySkilled

movements,

posture,

and

balance?

Regulate

muscle

tone

The

cerebellum

has

no

direct

connectionswith

musclesIt

functions

at

an

unconscious

levelThe

Brain

-

CerebellumReceives

a

variety

of

information?

Information

about

voluntary

muscle

activity

from

the

motorregion

of

the

cerebral

cortex?

Sensory

information

fromproprioceptors

throughout

thebody?

Information

from

the

visual

and

equilibrium

pathways

Integrates

this

information

and

determines

how

tointegrate

the

sensory

information

with

the

motorfunctions

to

elicit

a

coordinated

response?

Sends

its

coordination

plan

to

the

primary

motor

cortex?

The

primarymotor

cortex

then

signals

the

muscles

to

elicitthe

desired

responseThe

Brain

-

CerebellumCortical

Control

of

Voluntary

MovementPyramidal

Tracts?

Direct

pathways

from

the

primary

motor

cortex

to

thespinal

cord,

called

Corticospinal

tracts?

Control

small

groups

of

muscles

that

contractindependently

of

each

otherExtrapyramidal

Tracts?

Indirect

connections

between

the

brain

and

spinal

cord?

Includes

all

motor

control

pathways

outside

the

pyramidalsystem?

Control

large

groups

of

muscles

that

contract

together

tomaintain

posture

and

balancePyramidal

Tracts

Axons

of

neurons

in

these

tracts

terminatein

the

ventral

horn

of

the

spinal

cord?

Called

Upper

Motor

Neurons

Axons

of

neurons

in

these

tracts

cross

overto

the

opposite

side

of

the

CNS

in

the

areaof

the

medulla?

Called

Medullary

PyramidsPyramidal

TractsLateral

and

Ventral

Corticospinal

Tracts

Carry

nerve

impulses

for

skilled,

voluntarycontraction

of

the

skeletal

muscles Large

motor

pathways

that

descend

fromthe

cerebral

motor

cortex

to

the

motorneurons

in

the

ventral

horn

of

the

spinalcord?

The

largest

and

most

important

motor

tracts

inthe

bodyPyramidal

Tracts

The

Lateral

Corticospinal

tracts

cross

overin

the

region

of

the

medulla,

called

themedullary

pyramids

The

Ventral

Corticospinal

tracts

cross

overin

the

spinal

cord

From

the

medulla,

the

corticospinal

tractsdescend

to

the

spinal

cord

level

of

the

muscleto

be

innervated?

Both

lateral

and

ventral

corticospinal

tracts

synapsewith

either:Interneurons,

orMotor

neurons

in

the

ventral

horn

of

the

spinal

cord

Interneurons

synapse

with

lower

motorneurons

that

travel

directly

to

theneuromuscular

junction

of

the

skeletal

musclethe

CNS

wants

to

activatePyramidal

TractsPyramidal

Tracts

The

Corticospinal

Tracts

connect

the

left

cerebralmotorcortex

with

the

muscleson

the

right

side

of

thebody

and

vice

versaFor

example:?

The

brain

has

received

and

processed

sensory

information

thatcauses

it

to

direct

the

biceps

muscles

to

contract

to

lift

a

weight?

The

brain

sends

impulses

down

the

corticospinal

tracts

to

theC5-C7

levels

of

the

spinal

cord

to

synapse

with

the

appropriatemotor

neurons?

The

nerve

impulse

is

propogated

along

the

ventral

roots

of

thebrachial

plexus,

to

the

musculocutaneous

nerve,

whichinnervates

the

biceps?

The

biceps

muscle

contracts

to

lift

the

weightExtrapyramidal

Tracts

Motor

control

pathways

outside

of

thepyramidal

system

Indirect

connections

between

the

brain

andspinal

cord

Neurons

in

these

tracts

do

NOT

formsynapses

with

motor

neuronsInclude

two

tracts?

Reticulospinal

tracts?

Rubrospinal

tractsExtrapyramidal

TractsReticulospinal

Tracts

The

Lateral,

Anterior,

and

Medial

Reticulospinal

tractsare

motor

(efferent,

descending)?

Descend

from

the

reticular

formation,

which

is

located

in

thepons

and

medulla?

Elicits

involuntary

motor

responsesFunctions:?

Facilitate

extensor

motor

neurons

(promotes

muscle

tone)?

Facilitate

visceral

motor

function,

and?

Control

unskilled

movementsExtrapyramidal

TractsRubrospinal

tracts?

Motor

(efferent,

descending)

tractsdescendingfrom

thered

nucleus

(rubro-)

of

the

midbrain?

These

tracts

cross

over

in

the

brain

stem?

Elicits

involuntary

motor

responsesFunctions:?

Synapse

with

motor

neurons

that

will

transmit

impulses

tothe

neuromuscular

junction

of

the

muscle

that

willcontract?

Result

in

muscle

contractions

that

maintain

muscle

tonein

the

flexor

muscles

on

the

opposite

side

of

the

bodyFunctional

Human

Physiologyfor

the

Exercise

and

Sport

SciencesThe

Nervous

System:

Sensory

SystemsJennifer

L.

Doherty,

MS,

ATCDepartment

of

Health,

Physical

Education,

andRecreationFlorida

International

UniversitySensory

Receptors

Specialized

neuronal

structures

that

detecta

specific

form

of

energy

in

either

theinternal

or

external

environment?

Energy

is

detected

by

the

dendritic

end

organsof

sensory

(afferent)

neurons?

This

information

is

transmitted

to

the

CNS

Receptors

may

change

one

form

of

energyto

another?

For

example,

chemical

to

electrical

at

the

NMJTypes

of

Sensory

ReceptorsChemoreceptors?

Sensitive

to

chemical

concentrations

such

as

in

smelland

tasteNociceptors

or

pain

receptors?

Sensitive

to

tissue

damageThermoreceptors?

Sensitive

to

temperature,

either

to

heat

or

coldMechanoreceptors?

Sensitive

to

changes

in

mechanical

energy

such

as

pressure

or

themovement

of

fluidsBaroreceptors

detect

the

blood

pressure

in

certain

arteries

and

veins.Stretch

receptors

are

sensitive

to

changes

in

the

amount

of

inflation

in

thelungs.Proprioceptors

are

sensitive

to

changes

in

tension

in

the

muscles,

tendons,and

ligaments.Photoreceptors?

Sensitive

to

light

intensity

and

are

found

only

in

the

eyes.Sensory

TransductionSensory

impulses

are

generated

by

receptors?

The

energy

of

the

stimulus

is

absorbed?

The

energy

is

then

transduced

into

an

electrical

signalReceptor

potential?

A

stimulus

that

exceeds

the

threshold

intensityGraded

potential?

The

electrical

signal

that

is

produced

when

threshold

isreachedPropagation

of

a

nerve

impulseSensationThe

awareness

of

a

stimulusPerception?

The

brain’s

interpretation

of

the

sensory

information

providedby

the

sensory

receptorsSince

all

nerve

impulses

are

the

same,

the

only

differences

are:?

The

type

of

receptor

that

was

stimulated,

and?

The

region

of

the

brain

to

which

the

receptor

is

connected.For

example,

When

heat

receptors

in

the

2nd

finger

of

the

right

hand

arestimulated

by

a

lit

match,

the

region

of

the

brain

corresponding

tothat

part

of

the

body

will

perceive

pain

If

light

receptors

were

transplanted

to

the

region

of

the

brain

thatsenses

smell,

then

stimulation

of

the

light

receptorswouldresult

inan

odor

being

perceivedSensory

Adaptation

Sensory

adjustment

that

occurs

whenreceptors

are

continuously

stimulatedSensory

Coding?

Receptors

respond

to

continuous

stimulation

by

firing

at

slowerand

slower

rates?

Eventually

the

receptors

may

fail

to

send

any

signal

at

all

The

sense

of

smell

is

particularly

subject

to

sensoryadaptationFor

example?

When

you

are

in

a

room

with

a

strong

odor

you

will

noticethat

soon

you

cannot

smell

the

odor,

or

it

is

muchreduced?

The

smell

receptors

have

adapted

and

are

not

stimulatedagain

until

the

stimulus

changes?

Clothing

against

skin

is

another

exampleThe

Somatosensory

SystemThe

Somatosensory

Cortex?

Postcentral

Gyrus

of

CerebrumSensory

homunculusSomatic

sensory

and

proprioceptionThe

Somatosensory

SystemSomatosensory

Pathways?

Dorsal

Column-MedialLemniscus

Transmit

sensory

impulses

from

mechanoreceptorsandproprioceptors

to

the

thalamusCrosses

over

in

the

region

of

themedulla?

Spinothalamic

Tract

Transmits

sensory

impulses

from

thermoreceptors

andnocioceptors

to

the

thalamus

after

crossing

to

the

other

sidein

the

spinal

cordCrosses

over

in

the

spinal

cordSpinothalamic

Tracts

The

Lateral

and

Anterior

SpinothalamicTracts

are

sensory

(afferent,

ascending)?

Travel

from

the

spinal

cord

to

the

thalamus

Receive

sensory

input

from

the

receptorsfor:?

Pain

(from

free

nerve

endings)?

Temperature

(from

Pacinian

corpuscles)?

Deep

pressure

(from

Meissners

corpuscles)?

Touch

(from

End

bulbs

of

Krause

)Spinothalamic

Tracts Sensory

information

crosses

to

the

oppositeside

in

the

spinal

cord

The

sensory

information

ascends

to

thethalamus?

A

synapse

occurs

with

one

of

the

thalamic

nuclei

The

sensory

information

is

sent

from

thethalamus

to

sensory

cortex

of

the

cerebrum?

Located

in

the

post

central

gyrusFor

example:?

A

heat

receptor

(free

nerve

ending)

located

in

the

L3dermatome

on

the

anterior

thigh

is

stimulated

by

the

heatingpad

you

have

put

on

the

quadriceps

muscle

group

of

your

soreright

thigh?

The

impulse

travels

along

the

peripheral

nerve

through

thesensory

neuron

in

the

dorsal

root

ganglion

and

on

to

a

synapsewithan

internuncial

neuron

in

the

dorsal

horn

of

segment

L3?

From

there

the

fiber

carrying

the

next

impulse

crosses

over

tothe

left

side

of

the

spinal

cord

to

the

lateral

spinothalamic

tract,and

ascends

to

the

thalamus.?

Another

synapse

occurs

in

thethalamusand

the

next

impulseis

sent

to

the

sensory

cortex

of

the

cerebrum

where

the

brainwill

perform

its

integrative

and

decision

making

functions.?

A

decision

will

be

madewhether

to

instruct

themuscles

of

yourhands

and

arms

to

remove

the

heating

pad

because

it

is

toohot

or

leave

it

in

place.Pain

PerceptionMediated

primarily

through

free

nerve

endings?

Sensitive

to

a

variety

of

painful

or

noxious

stimuli

Changes

in

chemical

composition

of

body

fluids,such

as

decreased

pH

or

accumulation

ofmetabolic

wastes

can

stimulate

pain

receptors.Adaptation

to

pain

is

practically

non-existent?

Pain

sensation

can

be

triggered

by

a

single

stimulus

andis

longer

lasting

than

many

other

types

of

stimuli,

such

ashot,

cold,

or

smellPainPathwaysPain

impulses

are

transmitted

through

the

ascendingpathways

of

the

spinal

cord,

primarily

the

lateral

spinothalamictracts

to

the

brainNocioceptors

(pain

receptors)

located

in

the

skin?

When

stimulated,

send

pain

information

along

a

first

orderneuronFirst

order

neurons?

Deliver

sensory

impulses

from

the

receptor

to

the

dorsal

horn

ofthe

spinal

cord

where

it

synapses

on

a

second

order

neuronSecond

order

neruons?

Travel

in

the

spinothalamic

tract

to

the

thalamus

which

relaysthe

information

to

the

appropriate

area

of

the

primarysomatosensory

cortexPainPathways

Within

the

brain

most

of

the

pain

sensationterminates

in

the

reticular

formation

and

areprocessed

by

the

thalamus,

hypothalamusand

the

cerebral

cortex

The

brain,

after

evaluating

the

extent

of

thepain,

sends

information

back

along

adesignated

motor

tract

to

the

muscles

thatrequire

contraction

to

move

the

limb

awayfrom

the

source

of

painVisceral

PainUsually

not

very

well

localized?

It

may

feel

as

though

it

iscoming

from

another

part

of

the

bodythan

fromthe

organ

actually

affectedReferred

pain?

Results

from

common

nerve

pathways

that

bring

sensoryinformation

from

skin

or