The document discusses the muscular system and muscle tissue. It describes the functions of muscles which include voluntary movement, breathing, maintaining posture, and producing heat. It discusses the three main types of muscle tissue - skeletal, cardiac, and smooth muscle. Skeletal muscle is voluntarily controlled and attached to bones, cardiac muscle is found in the heart and contracts involuntarily, and smooth muscle is found in internal organs and skin and also contracts involuntarily. The document details muscle anatomy down to the protein filaments within muscle cells and explains the sliding filament model of muscle contraction where actin filaments slide over myosin filaments causing muscle shortening.

1. The Muscular SystemThe Muscular System
Chapter 36Chapter 36
Section 2Section 2
NotesNotes

3. Muscle SystemMuscle System
FunctionsFunctions
 Provides voluntaryProvides 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 doskip, jump, or do
push-upspush-ups
 Maintains postureMaintains posture
 Produces heatProduces heat

4. Functions ContinuedFunctions Continued
 Causes heart beatCauses heart beat
 Directs circulationDirects circulation
of bloodof blood
 RegulatesRegulates
bloodblood
pressurepressure
 Sends blood toSends blood to
different areas ofdifferent areas of
the bodythe body

5. Functions ContinuedFunctions Continued
 Provides movement ofProvides movement of
internal organsinternal organs
 Moves food throughMoves food through
digestive tractdigestive tract
 Enables bladder controlEnables bladder control
 Causes involuntary actionsCauses involuntary actions
 Reflex actionsReflex actions
 Adjusts opening of pupilsAdjusts opening of pupils
 Causes hair to stand onCauses hair to stand on
end ( )end ( )

6. Muscle TissueMuscle Tissue
CharacteristicsCharacteristics
 Is made up of contractileIs made up of contractile
fibersfibers
 Provides movementProvides movement
 Controlled by theControlled by the
nervous systemnervous system
 Voluntary- consciouslyVoluntary- consciously
controlledcontrolled
 Involuntary- not underInvoluntary- not under
conscious controlconscious control
 ExamplesExamples
 SkeletalSkeletal
 SmoothSmooth
 CardiacCardiac
CardiacCardiac
SkeletalSkeletal
SmoothSmooth

7. Types of MuscleTypes of Muscle
TissueTissue
 There areThere are
three mainthree main
types oftypes of
muscle tissuemuscle tissue
 SkeletalSkeletal
(striated)(striated)
 CardiacCardiac
(heart)(heart)
 SmoothSmooth
(visceral)(visceral)

8. Comparison of Muscle TypesComparison of Muscle Types
Muscle TypeMuscle Type CardiacCardiac
FunctionFunction
Movement ofMovement of
bonebone
Walls of internalWalls of internal
organs + in skinorgans + in skinLocationLocation
Attached toAttached to
bonebone
HeartHeart
SmoothSmoothSkeletalSkeletal
Striated- lightStriated- light
and dark bandsand dark bands
Many nucleiMany nuclei
StriatedStriated
One or twoOne or two
nucleinuclei
CharacteristicsCharacteristics
Non-striatedNon-striated
One nucleusOne nucleus
(visceral)(visceral)
Long + slenderLong + slender BranchingBranching
ShapeShape Spindle shapeSpindle shape
Control ModeControl Mode
Beating of heartBeating of heart
InvoluntaryInvoluntary InvoluntaryInvoluntary
Movement ofMovement of
internal organsinternal organs
VoluntaryVoluntary

9. LocationLocation
ofof
MusclesMuscles
 SkeletalSkeletal
MusclesMuscles
 AnteriorAnterior
viewview
QuadricepsQuadriceps
groupgroup
Rectus abdominisRectus abdominis
Quadriceps GroupQuadriceps Group
External ObliquesExternal Obliques
FrontalisFrontalis
MasseterMasseter
Tibialis AnteriorTibialis Anterior
DeltoidDeltoid
Pectoralis MajorPectoralis Majorbiceps brachiibiceps brachii
BrachioradialisBrachioradialis

10. LocationLocation
ofof
MusclesMuscles
 SkeletalSkeletal
MusclesMuscles
 PosteriorPosterior
viewview
Hamstring
group
TrapeziusTrapezius
HamstringHamstring
groupgroup
GastrocnemiusGastrocnemius
Latissimus dorsiLatissimus dorsi
GluteusGluteus
maximusmaximus
Triceps brachiiTriceps brachii

11. FF
AA
DD
CC
BB
EE
LL
KK
JJ
HH
GG
PP
OO
NN
MM
II
Muscles You Need toMuscles You Need to
KnowKnow 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
99
11
22
33
44
55
66
77
88
1010
1111
1212
1313
1414
1515
1616

12. Location of MusclesLocation of Muscles
 InvoluntaryInvoluntary
MusclesMuscles
 DiaphragmDiaphragm
 Digestive organsDigestive organs
 Arrector piliArrector pili
 HeartHeart
 Urinary bladderUrinary bladder
 Muscles aroundMuscles around
blood vesselsblood vessels

13. Muscle TissueMuscle Tissue
AnatomyAnatomy
bundle of musclebundle of muscle
fibers – fasciclefibers – fascicle

14. MM
uu
ss
cc
ll
ee
TT
II
ss
ss
uu
ee
AA
nn
aa
tt
oo
mm
yy
MuscleMuscle
FilamentsFilaments
MyofibrilsMyofibrils
Muscle FibersMuscle Fibers
FascicleFascicle
 Muscles are made up of bundles
of 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 of
protein
filaments

15. SarcomereSarcomere
MyofibriMyofibri
ll
 Contain two types ofContain two types of
protein filamentsprotein filaments
 Actin- thinActin- thin
proteinprotein
filamentsfilaments
 Myosin- thickMyosin- thick
protein filamentsprotein filaments
 Z disc- point ofZ disc- point of
anchor of actinanchor of actin
 Sarcomere-Sarcomere-
functional unit of afunctional unit of a
myofibril, regionmyofibril, region
between Z discs,between Z discs,
Thin FilamentsThin Filaments
ActinActin
MoleculeMolecule
Thick FilamentsThick Filaments
Myosin MoleculeMyosin Molecule
Z DiscZ Disc
SarcomereSarcomere

16. DD
CC
BB
AA
MuscleMuscle
TissueTissue
AnatomyAnatomy
 What parts do youWhat parts do you
remember?remember?
1. Muscle1. Muscle
2. Fascicle2. Fascicle
(bundle of fibers)(bundle of fibers)
3. Muscle fiber3. Muscle fiber
(muscle cell)(muscle cell)
4. Myofibrils4. Myofibrils
33
44
22
11

17. C
B
A
FG
D
E
II
 Muscle cellMuscle cell
 MyofibrilsMyofibrils
 MyosinMyosin
 SarcomereSarcomere
 Z DiscZ Disc
 ActinActin
 FascicleFascicle
 FilamentsFilaments
 MuscleMuscle
Muscle Tissue AnatomyMuscle Tissue Anatomy
ContinuedContinued
FF
EE GG
DD
CC
BB
AA
What parts do you remember?....continuedWhat parts do you remember?....continued
HH
HH
MyofibrilMyofibril
II

18. Mechanics of a MuscleMechanics of a Muscle
ContractionContraction
 What stimulates a muscle toWhat 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 sendsMotor neuron sends
impulse to muscle cellsimpulse to muscle cells
 One neuron will formOne neuron will form
synapses with manysynapses with many
muscle cellsmuscle cells
 What is this called?What is this called?
 A motor unitA motor unit
 Let’s take a look underLet’s take a look under
the microscope.…the microscope.…A motor unitA motor unit

19. Mechanics of a MuscleMechanics of a Muscle
ContractionContraction
 Where does stimulation occur?Where does stimulation occur?
 Neuromuscular junctionNeuromuscular junction
 How do motor neuronsHow do motor neurons
communicate withcommunicate with
muscle cells?muscle cells?
 Neurotransmitters (typicallyNeurotransmitters (typically
acetylcholine) carryacetylcholine) carry
impulse signal across the gapimpulse signal across the gap
 What happens when aWhat 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

20. Mechanics of a MuscleMechanics of a Muscle
ContractionContraction
 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

21. Mechanics of a MuscleMechanics of a Muscle
ContractionContraction
 What causes actin to slide overWhat causes actin to slide over
myosin?myosin?
 The head of myosin connectsThe head of myosin connects
to actin and pivots.to actin and pivots.
 What is this connection called?What is this connection called?
 cross-bridgecross-bridge
 The binding of the myosinThe binding of the myosin
heads throughout theheads throughout the
sarcomere occursarcomere occur
asynchronously…asynchronously…
 some myosin heads aresome myosin heads are
binding while other heads arebinding while other heads are
releasing the actin filaments.releasing the actin filaments.
 This process must beThis process must be
performed repeatedly during aperformed repeatedly during a
single muscle contraction sosingle muscle contraction so
that the muscle is able tothat the muscle is able to
generate a smooth forcegenerate a smooth force

22. Mechanics of a MuscleMechanics of a Muscle
ContractionContraction
 What provides the energy to swivel the head ofWhat 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 attached
to the Z-line) slide (are
actually pulled) inward
along the (thick)
myosin filaments
[blue], and the
sarcomere (measured
from one Z line to the
next) is shortened.
ATPATP

23. Mechanics of a MuscleMechanics of a Muscle
ContractionContraction
 When each sarcomere becomes shorter itWhen each sarcomere becomes shorter it
causes each myofibril to become shorter.causes each myofibril to become shorter.
 When eachWhen each
myofibril becomesmyofibril becomes
shorter it causesshorter it causes
the muscle fibersthe muscle fibers
to become shorterto become shorter
 When eachWhen each
muscle fibermuscle fiber
shortens theshortens the
overall muscleoverall muscle
contracts.contracts.
SarcomereSarcomere

24. Control of a MuscleControl of a Muscle
ContractionContraction
 How long does a muscle cellHow 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 theSo 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, moreTo get a stronger contraction, more
cells are stimulatedcells are stimulated
 A single cell can’t contract harderA single cell can’t contract harder

25. A Closer Look at Muscle ContractionA Closer Look at Muscle Contraction
““hot”hot”
guyguy
DeltoidDeltoid
musclemuscle
MuscleMuscle
FiberFiber
MyofibrilMyofibril
sarcomeresarcomere
ActinActin
MyosinMyosin

26. Macroscopic StructureMacroscopic Structure
of Muscleof Muscle _________- attaches_________- attaches
muscle to bonemuscle to bone
 _______- attachment_______- attachment
of muscle toof muscle to
immovable (fixed)immovable (fixed)
bone (anchors muscle)bone (anchors muscle)
 ________- attachment________- attachment
to bone that movesto 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

27. 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 musclesIt is important to understand that all muscles
move from the ________ pointmove from the ________ point
going toward the __________going toward the __________
point.point.
 It is because of theIt is because of the
placement of the musclesplacement of the muscles
that we canthat we can
move.move.
jointjoint
fixedfixed
movingmoving
insertioninsertion
originationorigination

28. Muscle MovementMuscle Movement
 TendonsTendons
 attach _________ to boneattach _________ to bone
 are inelasticare inelastic
 don’t stretch when the force ofdon’t stretch when the force of
the muscle acts on themthe muscle acts on them
 When muscle contracts,When muscle contracts,
it pulls on the _______it pulls on the _______
 Individual muscles canIndividual muscles can
only ____ in ____ directiononly ____ in ____ direction
 Muscles work inMuscles work in
opposing ______opposing ______
musclemuscle
bonebone
pullpull oneone
pairspairs

29. Muscle MovementMuscle Movement
 ______-______- Muscle that bends the joint whenMuscle that bends the joint when
contracted.contracted.
 ________-________- Muscle that straightens the jointMuscle that straightens the joint
when contracted.when contracted.
 __________ muscle__________ muscle
is short, firm, tightis short, firm, tight
and thicker around.and thicker around.
 _______ muscle is_______ muscle is
stretched, long, loosestretched, long, loose
and thinner around.and thinner around.
FlexorFlexor
ExtensorExtensor
RelaxedRelaxed
ContractedContracted

30. Muscle MovementMuscle Movement
 When theWhen the bicepsbiceps in the arm contracts thein the arm contracts the tricepstriceps
________________ causing ________ of the arm.causing ________ of the arm.
 When theWhen the tricepstriceps in the arm _________ thein the arm _________ the bicepsbiceps
relaxes causing ____________ of the arm.relaxes causing ____________ of the arm.
relaxesrelaxes
 ______ of muscles are______ of muscles are
needed because theneeded because the
only active _________only active _________
of a muscle is toof a muscle is to
_______, to lengthen it_______, to lengthen it
must be _________ bymust be _________ by
the action of anthe action of an
opposing _______.opposing _______.
bendingbending
contractscontracts
straighteningstraightening
PairsPairs
movementmovement
contractcontract
stretchedstretched
musclemuscle

31. Muscle MovementMuscle Movement
 The muscles, bones, and ligaments work
together to control body motion.
I amI am
gettinggetting
motionmotion
sicknessicknes
ss
Warning: This illusionWarning: This illusion
can make you feel verycan make you feel very
dizzy, especially if youdizzy, especially if you
are prone to motionare prone to motion
sicknesssickness

32. Muscles In ActionMuscles In Action
 Click above to get to this multimedia interactive HTMLClick above to get to this multimedia interactive HTML
document which will help you learn the muscle actionsdocument which will help you learn the muscle actions
of the human body.of the human body.
HYPERMUSCLE: MUSCLES IN ACTION

33. Muscle + BoneMuscle + Bone
InteractionInteraction
 Let’s review the structures involved inLet’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
BB
CC
FF FF
BB
FF
BB
CC
DD
EE
GG
DD CC
AA

34. 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 the
ankles, knees, or wrists.ankles, knees, or wrists.
SprainSprain
Result in pain, swelling, redness, bruising, andResult in pain, swelling, redness, bruising, and
difficulty using injured joint.difficulty using injured joint.

35. Muscle DisordersMuscle Disorders
 A strain is an injury to a muscle orA strain is an injury to a muscle or
tendon, and is often caused bytendon, and is often caused by
overuse, force, or stretching.overuse, force, or stretching.
 Injured areaInjured area
experiences:experiences:
 pain andpain and
sorenesssoreness
 swellingswelling
 warmth, bruising,warmth, bruising,
or rednessor redness
 difficulty using ordifficulty using or
moving themoving the
injured area in ainjured area in a
normal manner
StrainStrain

36. Muscle DisordersMuscle Disorders
 There are three degrees of muscle rupturesThere are three degrees of muscle ruptures
 A muscle tear may be partial or complete and caused either byA muscle tear may be partial or complete and caused either by
a direct blow or by overexertion.a direct blow or by overexertion.
 A first-degree strain involves less than 5 percent of the muscle.A first-degree strain involves less than 5 percent of the muscle.
 mild pain and not much loss of strength or range of motion.mild pain and not much loss of strength or range of motion.
 Mild tears referred to as pulled muscles.Mild tears referred to as pulled muscles.
 A second-degree tear is a greater rupture that stops short of aA second-degree tear is a greater rupture that stops short of a
complete tear.complete tear.
 Any contraction of the torn muscle will cause pain.Any contraction of the torn muscle will cause pain.
 There may be a defect of the muscle - a bump or an indentation -There may be a defect of the muscle - a bump or an indentation -
at the site of the most pain.at the site of the most pain.
 You should be able to partially contract the muscle, but not withoutYou should be able to partially contract the muscle, but not without
painpain
 A third-degree rupture is a complete tear across the width ofA third-degree rupture is a complete tear across the width of
the musclethe muscle
 You will be unable to contract the muscle.You will be unable to contract the muscle.
 This is what happens when someone suddenly drops whileThis is what happens when someone suddenly drops while
sprinting.sprinting.
 The torn end of the muscle may ball up and form a large lumpThe torn end of the muscle may ball up and form a large lump
under the skin, and a great deal of internal bleeding occurs.under the skin, and a great deal of internal bleeding occurs.
 Severely torn muscles may require surgery to heal properly.Severely torn muscles may require surgery to heal properly.
Muscle RupturesMuscle Ruptures

37. Muscle DisordersMuscle Disorders
 Muscle pull- very slight tearMuscle pull- very slight tear
 Chronic tear- gradual onset of painChronic tear- gradual onset of pain
 Acute tear- sudden dramatic painAcute tear- sudden dramatic pain
Muscle PullMuscle Pull Muscle TearMuscle Tear
MuscleMuscle
TearsTears

38. Muscle DisordersMuscle Disorders
 Shin splints is painShin splints is pain
resulting from damage toresulting 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.

39. Muscle DisordersMuscle Disorders
 R.I.C.E.R.I.C.E.
 Rest:Rest: Stop all activities whichStop 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 strainedWrap the strained
area to reduce swelling.area to reduce swelling.
 Elevation:Elevation: Keep the strained area asKeep the strained area as
close to the level of the heart as isclose to the level of the heart as is
conveniently possible to keep bloodconveniently possible to keep blood
from pooling in the injured area.from pooling in the injured area.
Treatment for Muscle InjuriesTreatment for Muscle Injuries

40. Muscle DisordersMuscle Disorders
 Muscle spasm- when A muscle (or even a fewMuscle spasm- when A muscle (or even a few
fibers of a muscle) involuntarily contractfibers of a muscle) involuntarily contract
 Muscle cramp- involuntarily + forciblyMuscle 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 fewCan last anywhere from a few
seconds to a quarter of an hourseconds 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

41. Muscle DisordersMuscle Disorders
 Tetanus is a preventable disease through vaccinationTetanus is a preventable disease through vaccination
 Caused by bacteria that enters the bodyCaused by bacteria that enters the body
through the skinthrough the skin
 Found in soil, dust and manureFound in soil, dust and manure
 Toxin bacteria produces interferes with nerveToxin bacteria produces interferes with nerve
transmission to your muscles and causestransmission 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 musclesTetanus 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 swallowingDifficulty swallowing
 Intestines often seize upIntestines often seize up
 Bladder fails to emptyBladder fails to empty
 AsphyxiationAsphyxiation
 Cardiac arrestCardiac arrest
TetanusTetanus

42. Muscle DisordersMuscle Disorders
 Produced naturally by the body to support such functions asProduced 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 theirPeople 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
 types of problemstypes of problems
 premature balding or hair losspremature balding or hair loss
 dizzinessdizziness
 mood swingsmood swings
 problems sleepingproblems sleeping
 nausea and vomitingnausea and vomiting
 high blood pressurehigh blood pressure
 aching jointsaching joints
 urinary problemsurinary problems
 shortening of final adult heightshortening of final adult height
 increased risk of heart disease,increased risk of heart disease,
stroke, and some cancersstroke, and some cancers
Anabolic SteroidsAnabolic Steroids

43. Muscle DisordersMuscle Disorders
 Cerebral palsy is a group of disorders that affect aCerebral 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 the
first few years of life, andfirst few years of life, and
usually don’t get worse over time.usually don’t get worse over time.
 People with cerebral palsyPeople with cerebral palsy
may have difficulty walking. They may alsomay have difficulty walking. They may also
have trouble with tasks such as writing orhave trouble with tasks such as writing or
using scissors.using scissors.
 Some people with cerebral palsy have otherSome people with cerebral palsy have other
medical conditions, including seizuremedical conditions, including seizure
disorders or mental impairment.disorders or mental impairment.
 Cerebral palsy happens when the areas ofCerebral palsy happens when the areas of
the brain that control movement and posturethe brain that control movement and posture
do not develop correctly or get damaged.do not develop correctly or get damaged.
Cerebral PalseyCerebral Palsey

44. Muscle DisordersMuscle Disorders
 Muscular DystrophyMuscular Dystrophy- most well known of- most well known of
hereditary diseaseshereditary diseases
 A genetic condition that describes over 20A genetic condition that describes over 20
genetic and hereditary muscle diseases.genetic and hereditary muscle diseases.
 Characterized by progressive skeletal muscleCharacterized by progressive skeletal muscle
weakness, defects in muscle proteins, and theweakness, defects in muscle proteins, and the
death of muscle cells and tissue.death of muscle cells and tissue.
 In some cases, cardiac and smooth musclesIn 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 Fallsrequent Falls
 Walking Difficulty + Waddling GaitWalking Difficulty + Waddling Gait
 Limited Range of MovementLimited Range of Movement
 Scoliosis (curvature of the spine)Scoliosis (curvature of the spine)
 Inability to WalkInability to Walk
 Muscle Atrophy and Drooping EyelidsMuscle Atrophy and Drooping Eyelids
Muscular DystrophyMuscular Dystrophy
Principal symptoms:Principal symptoms:

45. Muscle DisordersMuscle Disorders
 The characteristic symptom of myasthenia gravis is fatigability, whichThe 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 ofThe 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 mayThe 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 dayPatients initially complain of drooping eye lids that get worst as the day
goes on; they develop double vision, difficulty talking, and difficultygoes on; they develop double vision, difficulty talking, and difficulty
chewing.chewing.
 Muscle weakness increases during periods of activity and improvesMuscle weakness increases during periods of activity and improves
after periods of rest.after periods of rest.
 Myasthenia gravis-Myasthenia gravis- chronic autoimmunechronic autoimmune
neuromuscular disease characterized byneuromuscular disease characterized by
varying degrees of weakness of the skeletalvarying degrees of weakness of the skeletal
musclesmuscles
 Caused by a defect in the transmission ofCaused by a defect in the transmission of
nerve impulses at the neuromuscular junctionnerve impulses at the neuromuscular junction
 Antibodies (produced by the body's ownAntibodies (produced by the body's own
immune system) block, alter, or destroy theimmune system) block, alter, or destroy the
receptors for acetylcholine at thereceptors for acetylcholine at the
neuromuscular junction which prevents theneuromuscular junction which prevents the
muscle contraction from occurring.muscle contraction from occurring.
Myasthenia GravisMyasthenia Gravis

46. Muscle DisordersMuscle Disorders
 PoliomyelitisPoliomyelitis, often called, often called poliopolio is an acuteis an acute
viral infectious disease which is spread fromviral infectious disease which is spread from
person-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 theIn about 1% of cases the virus enters the (CNS) via the
blood stream.blood stream.
 Within the CNS, poliovirus infects andWithin the CNS, poliovirus infects and
destroys motordestroys motor
neurons.neurons.
PolioPolio
Old Polio
Asymmetric atrophy
& weakness
Atrophic right leg
(arrow) in patient
with paralytic polio 70
years in past
 The destruction ofThe destruction of
motor neuronsmotor neurons
causes musclecauses muscle
weakness andweakness and
flaccid paralysisflaccid paralysis
 Vaccination createdVaccination created
by Jonas Salk inby Jonas Salk in
1955 has eliminated1955 has eliminated
the diseasethe disease