The Muscular System Chapter 36 Section 2 Notes Keys Lecture Outline – The Muscular System PowerPoint Notes textbook questions

The Muscular SystemThe Muscular System

Chapter 36Chapter 36Section 2Section 2

NotesNotes

Muscle System FunctionsMuscle System Functions

Provides voluntary Provides voluntary movement of bodymovement of body Enables breathing, Enables breathing,

blinking, and smilingblinking, and smiling Allows you to hop, Allows you to hop,

skip, jump, or do skip, jump, or do push-ups push-ups

Maintains postureMaintains posture Produces heatProduces heat

Functions ContinuedFunctions Continued

Causes heart beatCauses heart beat Directs circulation Directs circulation

of blood of blood RegulatesRegulates

blood blood pressurepressure

Sends blood to Sends blood to different areas of different areas of the bodythe body

Functions ContinuedFunctions Continued Provides movement of Provides movement of

internal organsinternal organs Moves food through Moves food through

digestive tractdigestive tract Enables bladder controlEnables bladder control

Causes involuntary actionsCauses involuntary actions Reflex actions Reflex actions Adjusts opening of pupilsAdjusts opening of pupils Causes hair to stand on Causes hair to stand on

end ( )end ( )

Muscle Tissue Muscle Tissue CharacteristicsCharacteristics

Is made up of contractile Is made up of contractile fibersfibers

Provides movementProvides movement Controlled by the Controlled by the

nervous systemnervous system Voluntary- consciously Voluntary- consciously

controlledcontrolled Involuntary- not under Involuntary- not under

conscious controlconscious control ExamplesExamples

SkeletalSkeletal SmoothSmooth CardiacCardiac

CardiacCardiac

SkeletalSkeletal

SmoothSmooth

Types of Muscle TissueTypes of Muscle Tissue

There are There are three main three main types of types of muscle tissuemuscle tissue SkeletalSkeletal

(striated)(striated) CardiacCardiac

(heart)(heart) SmoothSmooth

(visceral)(visceral)

Comparison of Muscle TypesComparison of Muscle Types

Muscle TypeMuscle Type CardiacCardiac

FunctionFunctionMovement of Movement of

bonebone

Walls of internal Walls of internal organs + in skinorgans + in skinLocationLocation

Attached to Attached to bonebone

HeartHeart

SmoothSmoothSkeletalSkeletal

Striated- light Striated- light and dark bandsand dark bands

Many nucleiMany nuclei

StriatedStriatedOne or two One or two

nucleinuclei

CharacteristicsCharacteristicsNon-striatedNon-striatedOne nucleusOne nucleus

(visceral)(visceral)

Long + slenderLong + slender BranchingBranchingShapeShape Spindle shapeSpindle shape

Control ModeControl Mode

Beating of heartBeating of heart

InvoluntaryInvoluntary InvoluntaryInvoluntary

Movement of Movement of internal organsinternal organs

VoluntaryVoluntary

Location Location of of

MusclesMuscles SkeletalSkeletal

MusclesMuscles Anterior Anterior

viewview

Quadriceps Quadriceps groupgroup

Rectus abdominisRectus abdominis

Quadriceps GroupQuadriceps Group

External ObliquesExternal Obliques

FrontalisFrontalis

MasseterMasseter

Tibialis AnteriorTibialis Anterior

DeltoidDeltoidPectoralis MajorPectoralis Majorbiceps brachiibiceps brachii

BrachioradialisBrachioradialis

LocationLocationof Musclesof Muscles SkeletalSkeletal

MusclesMuscles PosteriorPosterior

viewview

Hamstring group

TrapeziusTrapezius

Hamstring Hamstring groupgroup

GastrocnemiusGastrocnemius

Latissimus dorsiLatissimus dorsi

Gluteus Gluteus maximusmaximus

Triceps brachiiTriceps brachii

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LL

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JJ

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PP

OO

NN

MM

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Muscles You Need to KnowMuscles You Need to Know 1. brachioradialis1. brachioradialis 2. biceps brachii2. biceps brachii 3. deltoid3. deltoid 4. external oblique4. external oblique 5. frontalis5. frontalis 6. gastrocnemius6. gastrocnemius 7. gluteus maximus7. gluteus maximus 8. hamstring group8. hamstring group 9. latissimus dorsi9. latissimus dorsi 10. masseter10. masseter 11. pectoralis major11. pectoralis major 12. quadriceps group12. quadriceps group 13. rectus abdominis13. rectus abdominis 14. tibialis anterior14. tibialis anterior 15. trapezius15. trapezius 16. triceps brachii16. triceps brachii

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1111

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Location of MusclesLocation of Muscles

InvoluntaryInvoluntaryMusclesMuscles DiaphragmDiaphragm Digestive organsDigestive organs Arrector pili Arrector pili HeartHeart Urinary bladderUrinary bladder Muscles aroundMuscles around

blood vesselsblood vessels

Muscle Tissue AnatomyMuscle Tissue Anatomy

bundle of muscle bundle of muscle fibers – fasciclefibers – fascicle

MMuussccllee

TTIIssssuuee

AAnnaattoommyy

MuscleMuscle

FilamentsFilaments

MyofibrilsMyofibrils

Muscle FibersMuscle Fibers

FascicleFascicle

Muscles are made up of bundlesof muscle fibers, called fascicles Fascicle is a bundle of muscle

fibers A muscle fiber is a muscle

cell….made up of many small myofibrils

Myofibrils contain filaments

Two types ofprotein filaments

SarcomereSarcomere

MyofibrilMyofibril

Contain two types of Contain two types of protein filamentsprotein filaments Actin- thinActin- thin

proteinproteinfilamentsfilaments

Myosin- thickMyosin- thickprotein filamentsprotein filaments

Z disc- point of Z disc- point of anchor of actinanchor of actin

Sarcomere- Sarcomere- functional unit of a functional unit of a myofibril, region myofibril, region between Z discs, between Z discs,

Thin FilamentsThin Filaments

ActinActinMoleculeMolecule

Thick FilamentsThick Filaments

Myosin MoleculeMyosin Molecule

Z DiscZ Disc

SarcomereSarcomere

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BBAA

Muscle TissueMuscle TissueAnatomyAnatomy

What parts do you What parts do you remember?remember?

1. Muscle1. Muscle

2. Fascicle 2. Fascicle (bundle of fibers) (bundle of fibers)

3. Muscle fiber 3. Muscle fiber (muscle cell) (muscle cell)

4. Myofibrils4. Myofibrils33

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A

FG

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Muscle cell Muscle cell MyofibrilsMyofibrils MyosinMyosin SarcomereSarcomere Z DiscZ Disc

ActinActin FascicleFascicle FilamentsFilaments MuscleMuscle

Muscle Tissue Anatomy ContinuedMuscle Tissue Anatomy Continued

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EE GG

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What parts do you remember?....continuedWhat parts do you remember?....continued

HH

HH

MyofibrilMyofibril

II

Mechanics of a Muscle Mechanics of a Muscle ContractionContraction

What stimulates a muscle to What stimulates a muscle to contract?contract? Your nervous systemYour nervous system

What cells are involved?What cells are involved? Muscle cells and a motor neuronMuscle cells and a motor neuron Motor neuron sends Motor neuron sends

impulse to muscle cellsimpulse to muscle cells One neuron will form One neuron will form

synapses with many synapses with many muscle cellsmuscle cells

What is this called?What is this called? A motor unitA motor unit Let’s take a look under Let’s take a look under

the microscope.…the microscope.…A motor unitA motor unit


Where does stimulation occur?Where does stimulation occur? Neuromuscular junctionNeuromuscular junction

How do motor neurons How do motor neurons communicate with communicate with muscle cells?muscle cells? Neurotransmitters (typicallyNeurotransmitters (typically

acetylcholine) carryacetylcholine) carryimpulse signal across the gapimpulse signal across the gap

What happens when a What happens when a muscle cell is stimulated?muscle cell is stimulated? Calcium ions are released into the muscle cellCalcium ions are released into the muscle cell

Myofibrils are surrounded by

calcium-containing

sarcoplasmic reticulum.

NeurotransmittersNeurotransmitters


What do calcium ions do?What do calcium ions do? Cause interaction between actin and myosinCause interaction between actin and myosin

How do actin and myosin interact?How do actin and myosin interact? Actin filaments slide over the myosin filaments.Actin filaments slide over the myosin filaments.

What model explains this?What model explains this? Sliding Filament ModelSliding Filament Model


What causes actin to slide over What causes actin to slide over myosin?myosin? The head of myosin connects The head of myosin connects

to actin and pivots.to actin and pivots. What is this connection called?What is this connection called?

cross-bridge cross-bridge The binding of the myosin The binding of the myosin

heads throughout the heads throughout the sarcomere occur sarcomere occur asynchronously…asynchronously… some myosin heads are some myosin heads are

binding while other heads are binding while other heads are releasing the actin filaments. releasing the actin filaments.

This process must be This process must be performed repeatedly during a performed repeatedly during a single muscle contraction so single muscle contraction so that the muscle is able to that the muscle is able to generate a smooth forcegenerate a smooth force


What provides the energy to swivel the head of What provides the energy to swivel the head of myosin? _____myosin? _____

How exactly does the sliding filament model work?How exactly does the sliding filament model work? In the sliding filament model of muscle contraction, the

(thin) actin filaments[red] (that are attachedto the Z-line) slide (areactually pulled) inward along the (thick)myosin filaments [blue], and the sarcomere (measuredfrom one Z line to thenext) is shortened.

ATPATP


When each sarcomere becomes shorter it When each sarcomere becomes shorter it causes each myofibril to become shorter.causes each myofibril to become shorter.

When each When each myofibril becomesmyofibril becomesshorter it causes shorter it causes the muscle fibers the muscle fibers to become shorterto become shorter

When each When each muscle fiber muscle fiber shortens the shortens the overall muscle overall muscle contracts.contracts.

SarcomereSarcomere

Control of a Muscle Control of a Muscle ContractionContraction

How long does a muscle cell How long does a muscle cell remain contracted?remain contracted? Until the release of acetylcholineUntil the release of acetylcholine

stops.stops. How strongly does a muscle fiber contract?How strongly does a muscle fiber contract?

To it’s fullest extent.To it’s fullest extent. All-or-none responseAll-or-none response

So what controls the So what controls the strength of a contraction?strength of a contraction? Number of muscle cells recruitedNumber of muscle cells recruited To get a stronger contraction, more To get a stronger contraction, more

cells are stimulatedcells are stimulated A single cell can’t contract harderA single cell can’t contract harder

A Closer Look at Muscle ContractionA Closer Look at Muscle Contraction

““hot”hot”guyguy

Deltoid Deltoid musclemuscle

MuscleMuscleFiberFiber

MyofibrilMyofibril

sarcomeresarcomere

ActinActin

MyosinMyosin

Macroscopic Structure Macroscopic Structure of Muscle of Muscle

_________- attaches _________- attaches muscle to bonemuscle to bone

_______- attachment _______- attachment of muscle to of muscle to immovable (fixed) immovable (fixed) bone (anchors muscle)bone (anchors muscle)

________- attachment ________- attachment to bone that moves to bone that moves when muscle contractswhen muscle contracts

_____- bulging middle _____- bulging middle part of the musclepart of the muscle

Belly ofBelly of BicepsBiceps

TendonTendon

OriginOrigin

InsertionInsertion

BellyBelly

Muscle MovementMuscle Movement Muscles originate on a _____bone in our body, Muscles originate on a _____bone in our body,

cross over a ______, and insert onto a ______ cross over a ______, and insert onto a ______ bone. bone.

It is important to understand that all muscles It is important to understand that all muscles move from the ________ point move from the ________ point going toward the __________ going toward the __________ point. point.

It is because of the placement It is because of the placement of the muscles that we can of the muscles that we can move.move.

jointjointfixedfixed

movingmoving

insertioninsertionoriginationorigination

Muscle MovementMuscle Movement Tendons Tendons

attach _________ to boneattach _________ to bone are inelastic are inelastic don’t stretch when the force of don’t stretch when the force of

the muscle acts on them the muscle acts on them When muscle contracts, When muscle contracts,

it pulls on the _______it pulls on the _______ Individual muscles can Individual muscles can

only ____ in ____ directiononly ____ in ____ direction Muscles work in Muscles work in

opposing ______opposing ______

musclemuscle

bonebone

pullpull oneone

pairspairs

Muscle MovementMuscle Movement ______-______- Muscle that bends the joint when Muscle that bends the joint when

contracted.contracted. ________-________- Muscle that straightens the joint Muscle that straightens the joint

when contracted.when contracted. __________ muscle__________ muscle

is short, firm, tight is short, firm, tight and thicker around.and thicker around.

_______ muscle is _______ muscle is stretched, long, loose stretched, long, loose and thinner around.and thinner around.

FlexorFlexor

ExtensorExtensor

RelaxedRelaxed

ContractedContracted

Muscle MovementMuscle Movement

When the When the bicepsbiceps in the arm contracts the in the arm contracts the triceps triceps ________________ causing ________ of the arm. causing ________ of the arm.

When the When the tricepstriceps in the arm _________ the in the arm _________ the bicepsbiceps relaxes causing ____________ of the arm.relaxes causing ____________ of the arm.

relaxesrelaxes

______ of muscles are ______ of muscles are needed because the needed because the only active _________ only active _________ of a muscle is to of a muscle is to _______, to lengthen it _______, to lengthen it must be _________ by must be _________ by the action of an the action of an opposing _______. opposing _______.

bendingbendingcontractscontracts

straighteningstraightening

PairsPairs

movementmovement

contractcontractstretchedstretched

musclemuscle

Muscle MovementMuscle Movement

The muscles, bones, and ligaments work together to control body motion.

I am I am getting getting motion motion sicknessicknes

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Warning: This illusion Warning: This illusion can make you feel very can make you feel very dizzy, especially if you dizzy, especially if you

are prone to motion are prone to motion sicknesssickness

Muscles In ActionMuscles In Action

Click above to get to this multimedia interactive HTML Click above to get to this multimedia interactive HTML document which will help you learn the muscle actions document which will help you learn the muscle actions of the human body. of the human body.

HYPERMUSCLE: MUSCLES IN ACTION

Muscle + Bone Muscle + Bone InteractionInteraction

Let’s review the structures involved in Let’s review the structures involved in movement at a joint. movement at a joint.

LigamentLigament TendonTendon CartilageCartilage Body (Belly)Body (Belly) OriginOrigin InsertionInsertion Contracted muscleContracted muscle Relaxed muscleRelaxed muscle FlexorFlexor ExtensorExtensor

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Muscle DisordersMuscle Disorders

A sprain is a wrenching, twisting or stretchingA sprain is a wrenching, twisting or stretching injury to a ligament. injury to a ligament.

Sprains often affect theSprains often affect theankles, knees, or wrists.ankles, knees, or wrists.

SprainSprain

Result in pain, swelling, redness, bruising, and Result in pain, swelling, redness, bruising, and difficulty using injured joint.difficulty using injured joint.


A strain is an injury to a muscle or tendon, and A strain is an injury to a muscle or tendon, and is often caused by overuse, force, or stretching.is often caused by overuse, force, or stretching.

Injured area Injured area experiences: experiences: pain and sorenesspain and soreness swelling swelling warmth, bruising, warmth, bruising,

or redness or redness difficulty using or difficulty using or

moving the injured moving the injured area in a normal area in a normal mannermanner

StrainStrain

There are three degrees of muscle There are three degrees of muscle ruptures ruptures

A muscle tear may be partial or A muscle tear may be partial or complete and caused either by a complete and caused either by a direct blow or by overexertion.direct blow or by overexertion.

A first-degree strain involves less A first-degree strain involves less than 5 percent of the muscle. than 5 percent of the muscle. mild pain and not much loss of mild pain and not much loss of

strength or range of motion.strength or range of motion. Mild tears referred to as pulled Mild tears referred to as pulled

muscles.muscles.

Muscle RupturesMuscle Ruptures

2nd2nd

A second-degree tear is a greater rupture A second-degree tear is a greater rupture that stops short of a complete tear.that stops short of a complete tear.

There may be a defect of the muscle - a There may be a defect of the muscle - a bump or an indentation - at the site of the bump or an indentation - at the site of the most pain. most pain.

You should be able to partially contract You should be able to partially contract the muscle, but not without painthe muscle, but not without pain

3rd3rd

A third-degree rupture is a complete tear A third-degree rupture is a complete tear across the width of the muscleacross the width of the muscle

You will be unable to contract the muscle. You will be unable to contract the muscle. This is what happens when someone This is what happens when someone

suddenly drops while sprinting. suddenly drops while sprinting. The torn end of the muscle may ball up and The torn end of the muscle may ball up and

form a large lump under the skin, and a form a large lump under the skin, and a great deal of internal bleeding occurs. great deal of internal bleeding occurs.

Severely torn muscles may require surgery Severely torn muscles may require surgery to heal properly.to heal properly.


Muscle pull- very slight tearMuscle pull- very slight tear Chronic tear- gradual onset of painChronic tear- gradual onset of pain Acute tear- sudden dramatic pain Acute tear- sudden dramatic pain

Muscle PullMuscle Pull Muscle TearMuscle Tear

Muscle Muscle TearsTears


Shin splints is pain Shin splints is pain resulting from damage to resulting from damage to the muscles along the shin.the muscles along the shin.

Pain is felt in different areas, depending on which muscles are affected.

Shin splintsShin splints

Shin splints represent an "overuse injury" and occur most commonly in runners.


R.I.C.E.R.I.C.E. Rest:Rest: Stop all activities which Stop all activities which

cause pain. cause pain. Ice:Ice: Helps reduce swelling. Helps reduce swelling.

Never ice more than 10-15 min. Never ice more than 10-15 min. at a time. Protect the skin. at a time. Protect the skin.

Compression:Compression: Wrap the strained Wrap the strained area to reduce swelling. area to reduce swelling.

Elevation:Elevation: Keep the strained area as Keep the strained area as close to the level of the heart as is close to the level of the heart as is conveniently possible to keep blood conveniently possible to keep blood from pooling in the injured area.from pooling in the injured area.

Treatment for Muscle InjuriesTreatment for Muscle Injuries


Muscle spasm- when A muscle (or even a few Muscle spasm- when A muscle (or even a few fibers of a muscle) involuntarily contract fibers of a muscle) involuntarily contract

Muscle cramp- involuntarily + forcibly Muscle cramp- involuntarily + forcibly contracted muscle that does not relaxcontracted muscle that does not relax A forceful + sustained spasmA forceful + sustained spasm Nick named charley horseNick named charley horse

CrampsCrampsSpasmsSpasms

Can last anywhere from a few Can last anywhere from a few seconds to a quarter of an hour seconds to a quarter of an hour

Caused by strain or injuryCaused by strain or injury

Muscle feels tied up in knotsMuscle feels tied up in knots


Tetanus is a preventable disease through vaccination Tetanus is a preventable disease through vaccination Caused by bacteria that enters the body Caused by bacteria that enters the body

through the skin through the skin Found in soil, dust and manure Found in soil, dust and manure Toxin bacteria produces interferes with nerve Toxin bacteria produces interferes with nerve

transmission to your muscles and causes transmission to your muscles and causes them to seize up in painful spasms.them to seize up in painful spasms.

Tetanus typically starts in the jaw and muscles Tetanus typically starts in the jaw and muscles of the face, quickly spreading to the arms and legs. of the face, quickly spreading to the arms and legs.

““Lockjaw”Lockjaw” Difficulty swallowing Difficulty swallowing Intestines often seize upIntestines often seize up Bladder fails to emptyBladder fails to empty Asphyxiation Asphyxiation Cardiac arrest Cardiac arrest

TetanusTetanus


Produced naturally by the body to support such functions as Produced naturally by the body to support such functions as fighting stress and promoting growth and developmentfighting stress and promoting growth and development

Referred to as roids, juice, hype, weight trainers, gym candy, Referred to as roids, juice, hype, weight trainers, gym candy, arnolds, stackers, or pumpersarnolds, stackers, or pumpers

People use steroid pills, gels, creams, or injections to improve their People use steroid pills, gels, creams, or injections to improve their sports performance or the way they look. sports performance or the way they look.

Anabolic steroids cause many different types of problemsAnabolic steroids cause many different types of problems

Anabolic SteroidsAnabolic Steroids

Anabolic Steroid Anabolic Steroid ProblemsProblems


Cerebral palsy is a group of disorders that affect a Cerebral palsy is a group of disorders that affect a person's ability to move and to maintain balance andperson's ability to move and to maintain balance and posture. posture.

The disorders appear in theThe disorders appear in thefirst few years of life, and first few years of life, and usually don’t get worse over time. usually don’t get worse over time.

People with cerebral palsy People with cerebral palsy may have difficulty walking. They may also may have difficulty walking. They may also have trouble with tasks such as writing or have trouble with tasks such as writing or using scissors. using scissors.

Some people with cerebral palsy have other Some people with cerebral palsy have other medical conditions, including seizure medical conditions, including seizure disorders or mental impairment. disorders or mental impairment.

Cerebral palsy happens when the areas of Cerebral palsy happens when the areas of the brain that control movement and posture the brain that control movement and posture do not develop correctly or get damaged.do not develop correctly or get damaged.

Cerebral PalseyCerebral Palsey


Muscular DystrophyMuscular Dystrophy- most well known of - most well known of hereditary diseaseshereditary diseases

A genetic condition that describes over 20 A genetic condition that describes over 20 genetic and hereditary muscle diseases.genetic and hereditary muscle diseases.

Characterized by progressive skeletal muscle Characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the weakness, defects in muscle proteins, and the death of muscle cells and tissue.death of muscle cells and tissue.

In some cases, cardiac and smooth muscles In some cases, cardiac and smooth muscles are affected. are affected.

Progressive Muscular Wasting (weakness) Progressive Muscular Wasting (weakness) Poor Balance and FPoor Balance and Frequent Falls requent Falls Walking Difficulty + Waddling Gait Walking Difficulty + Waddling Gait Limited Range of Movement Limited Range of Movement Scoliosis (curvature of the spine) Scoliosis (curvature of the spine) Inability to Walk Inability to Walk Muscle Atrophy and Drooping EyelidsMuscle Atrophy and Drooping Eyelids

Muscular DystrophyMuscular Dystrophy

Principal symptoms: Principal symptoms:


The characteristic symptom of myasthenia gravis is fatigability, which The characteristic symptom of myasthenia gravis is fatigability, which means that a muscle that is used repeatedly starts to become weak. means that a muscle that is used repeatedly starts to become weak.

The symptoms usually start in the face and spread to the other parts of The symptoms usually start in the face and spread to the other parts of the body as the disease progresses. the body as the disease progresses.

Certain muscles such as those that control eye and eyelid movement, Certain muscles such as those that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are often involvedfacial expression, chewing, talking, and swallowing are often involved

The muscles that control breathing and neck and limb movements may The muscles that control breathing and neck and limb movements may also be affected. also be affected.

Patients initially complain of drooping eye lids that get worst as the Patients initially complain of drooping eye lids that get worst as the day goes on; they develop double vision, difficulty talking, and difficulty day goes on; they develop double vision, difficulty talking, and difficulty chewing. chewing.

Muscle weakness increases during periods of activity and improves Muscle weakness increases during periods of activity and improves after periods of rest. after periods of rest.

Myasthenia gravis-Myasthenia gravis- chronic autoimmune chronic autoimmune neuromuscular disease characterized by varying neuromuscular disease characterized by varying degrees of weakness of the skeletal musclesdegrees of weakness of the skeletal muscles

Caused by a defect in the transmission of nerve Caused by a defect in the transmission of nerve impulses at the neuromuscular junctionimpulses at the neuromuscular junction

Antibodies (produced by the body's own immune Antibodies (produced by the body's own immune system) block, alter, or destroy the receptors for system) block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction acetylcholine at the neuromuscular junction which prevents the muscle contraction from which prevents the muscle contraction from occurring. occurring.

Myasthenia GravisMyasthenia Gravis


PoliomyelitisPoliomyelitis, often called , often called poliopolio is an acute is an acuteviral infectious disease which is spread fromviral infectious disease which is spread fromperson-to-person via the fecal-oral route. person-to-person via the fecal-oral route.

The majority of polio infections are asymptomatic. The majority of polio infections are asymptomatic. In about 1% of cases the virus enters the (CNS) via the In about 1% of cases the virus enters the (CNS) via the

blood stream. blood stream. Within the CNS, poliovirus infects and Within the CNS, poliovirus infects and

destroys motor destroys motor neurons. neurons.

PolioPolio

Old PolioAsymmetric atrophy & weaknessAtrophic right leg (arrow) in patient with paralytic polio 70 years in past

The destruction of The destruction of motor neurons motor neurons causes muscle causes muscle weakness and weakness and flaccid paralysisflaccid paralysis

Vaccination created Vaccination created by Jonas Salk in by Jonas Salk in 1955 has eliminated 1955 has eliminated the diseasethe disease

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The Muscular System Chapter 36 Section 2 Notes Keys Lecture Outline – The Muscular System PowerPoint Notes textbook questions