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Muscular System

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Title: Muscular System


1
Muscular System
  • Muscle Tissue
  • The Muscular System

2
Muscle Tissue
  • Introduction
  • Skeletal Muscle Tissue The Muscular System
  • Anatomy of Skeletal Muscle
  • Contraction of Skeletal Muscle
  • Muscle Mechanics

3
Muscle Tissue
  • Aging the Muscular System
  • Integration With Other Systems
  • Cardiac Muscle Tissue
  • Smooth Muscle Tissue

4
Introduction
  • Importance to body function
  • Importance to human activity
  • Active passive forces

5
Learning Objectives
  • Importance
  • Discuss the central role of muscle tissue in a
    variety of human activities and necessary body
    functions
  • Active Forces
  • Compare contrast tension, compression,
    resistance

6
ImportanceFunction Activity
  • Human activity
  • gross movements of the body
  • communication
  • speaking
  • facial expression gestures
  • Body function
  • circulation
  • respiration
  • digestion
  • reproduction

7
Body Movement
8
Communication
9
Bodily Functions
10
Active Passive Forces
  • Resistance
  • passive force opposing movement
  • dependent on weight, shape, friction, etc
  • Tension
  • active force applied to an object to produce
    movement
  • when applied tension gt resistance, object is
    pulled toward source of tension
  • Compression (not assoc. w/ muscle movement)
  • active force applied to an object to produce
    movement
  • when applied compression gt resistance, object is
    pushed away from source of compression

11
Muscle Contraction Produces Tension
RESISTANCE
TENSION
12
Skeletal Muscle Tissue The Muscular System
  • Tissue characteristics
  • Functions of muscle tissue

13
Learning Objectives
  • Characteristics Functions
  • Describe the characteristics functions of
    muscle tissue

14
Muscle Tissue
  • One of 4 primary tissue types of the body
  • Types of muscle tissue
  • skeletal
  • cardiac
  • smooth
  • Body muscles are organs
  • that contain skeletal muscle tissue, connective
    tissues, nerves, epithelial tissue smooth
    muscle tissue (in blood vessels)

15
Muscle Tissue Types
skeletal muscle
smooth muscle
cardiac muscle
16
Functions ofSkeletal Muscle Tissue
  • Produce skeletal movement
  • Maintain posture body position
  • Support soft tissues
  • Guard entrances into exists out of the body
  • Maintain body temperature

Mr. G
Before he got married
17
Anatomy of Skeletal Muscle
  • Connective tissue organization
  • Blood vessels nerves
  • Microanatomy of skeletal muscle fibers

18
Learning Objectives
  • Tissue Structure
  • Describe the organization of muscle at the tissue
    level
  • Cellular Structure
  • Explain the unique characteristics of skeletal
    muscle fibers
  • Organelle Structure
  • Identify the structural components of a sarcomere

19
Connective TissueOrganization
  • Surrounding Sheaths
  • Epimysium
  • Perimysium
  • Endomysium
  • Tendons

20
Connective Tissue Organization
  • Epimysium
  • outer connective tissue layer
  • dense layer of collagen fibers
  • deep fascia
  • surrounds entire muscle
  • Perimysium
  • middle connective tissue layer
  • collagen elastic fibers
  • contains blood vessels nerves
  • surrounds fascicles dividing muscle into
    compartments

21
Connective Tissue Organization
  • Endomysium
  • inner connective tissue layer
  • delicate c.t.
  • surrounds muscle fibers satellite cells
  • satellite cells (stem cells)

22
Connective Tissue Organization
  • Epimysium, perimysium, endomysium unite at
    muscle ends to form
  • Tendons
  • linear bundle attaching muscle to bone
  • Aponeuroses
  • broad sheet attaching muscle to bone same
    function as tendon

23
Connective Tissue Organization
Animation
24
Blood Vessels Nerves
blood vessels
nerve
25
Microanatomy
  • Organelles of Skeletal Muscle Fibers
  • Sarcomere Organization
  • Microfilament Structure

26
Microanatomy of Skeletal Muscle Fibers
  • Muscle fiber muscle cell
  • long, thin (among largest cells in body)
  • multinucleate peripheral, oval nuclei
  • Sarcolemma cell membrane
  • openings for penetrating tubules
  • established membrane potential due to Na-K ion
    exchange pumps

27
Microanatomy of Skeletal Muscle Fibers
  • Sarcoplasm cytoplasm
  • contains contractile proteins
  • contains numerous mitochondria
  • Sarcoplasmic reticulum (SR) endoplasmic
    reticulum
  • terminal cisternae fused SR tubules
  • triads regions where T tubules SR cisternae
    contact

28
Microanatomy of Skeletal Muscle Fibers
  • Transverse tubules T tubules
  • continuous w/ sarcolemma
  • network throughout cell
  • close contact w/ SR
  • Myofibrils
  • 100s-1000s of bundles of myofilaments
  • thin filaments
  • thick filaments

29
Microanatomy of Skeletal Muscle Fibers
  • Sarcomere
  • repeating units in myofibrils
  • linked end-to-end
  • functional unit of a muscle fiber
  • components
  • thick protein filaments
  • thin protein filaments
  • proteins stabilizing thick thin filaments
  • proteins regulating interaction btw/ thin thick
    filaments

30
Sarcomere Organization
  • Banded appearance due to overlap of thick thin
    filaments
  • A bands appear dark
  • I bands appear light
  • A band contains thick thin filaments
  • M line
  • center of sarcomere
  • thick filaments only - connected by stabilizing
    protein

31
Sarcomere Organization
  • A band (cont)
  • H zones
  • lateral to M line
  • thick filaments only
  • Zones of overlap
  • lateral to H zones
  • thick thin filaments overlap

32
Sarcomere Organization
  • I bands contain thin filaments only
  • edges of sarcomere
  • Z lines
  • boundaries btw/ adjacent sarcomeres
  • protein complexes attached to thin filaments

33
Sarcomere Organization
Note A I bands peripheral nuclei
A
I
34
Functional Organization
35
Thin Filaments
  • Composition (proteins)
  • F actin
  • twisted filament of G actin globular proteins
  • contains active sites that can bind to thick
    filaments
  • tropomyosin
  • protein cover over active sites of F actin
  • troponin
  • binds tropomyosin to active site
  • contains Ca2 receptor

36
Thin Filaments
  • Troponin-tropomyosin complex
  • reacts to bound Ca2 by uncovering active sites
    on F actin of thin filament
  • necessary for contraction

37
Thick Filaments
  • Composition (protein)
  • myosin
  • subunits tail head
  • tail
  • binds to other myosin molecules
  • head
  • projects outward toward thin filament
  • called cross-bridges

38
Thick Thin Filament Structure
39
ContractionOf Skeletal Muscle
  • The control of skeletal muscle activity
  • Relaxation
  • The contraction cycle
  • Length-tension relationships

40
Learning Objectives
  • Neuromuscular Junction
  • Identify the components of the neuromuscular
    junction summarize the events involved in the
    neural control of skeletal muscle function
  • Muscle Cell Contraction
  • Explain the key steps involved in the contraction
    of a skeletal muscle fiber

41
Control of Skeletal Muscle Activity
  • Neuromuscular junction
  • neural axon branch terminates w/ synaptic
    terminal at every muscle fiber
  • synaptic terminal contains neurotransmitter
    acetylcholine (ACh)
  • synaptic cleft separates terminal from muscle
    fiber sarcolemma

42
Control of Skeletal Muscle Activity
  • Neuromuscular junction
  • motor end plate sarcolemma surface w/ ACh
    receptors
  • acetylcholinesterase (AChE) in cleft breaks
    down ACh
  • ACh receptors of motor end plate bind to ACh
    released from synaptic terminal and respond by
    opening gated ion channels in sarcolemma

43
Membrane PotentialElectrochemical Gradient
positive charge due to ? Na
negative charge due to ? protein ? a.a. ?
F.A.
44
Neural Stimulation of Muscle Fibers
  • Step 1. Arrival of action potential.
  • action potential electric impulse travels down
    axon of neuron
  • enters synaptic terminal of neuron
  • Step 2. Release of ACh.
  • exocytosis synaptic vesicles containing ACh
    fuse w/ neurolemma
  • ACh enters synaptic cleft

45
Neural Stimulation of Muscle Fibers
  • Step 3. ACh binds at motor end plate.
  • ACh diffuses across cleft binds to ACh
    receptors of sarcolemma
  • gated Na-channel proteins open sarcolemma
    becomes permeable to Na
  • Na floods into sarcoplasm

46
Neural Stimulation of Muscle Fibers
  • Step 4. Appearance of action potential in
    sarcolemma.
  • Na influx results in action potential at motor
    end plate
  • action potential spreads across the excitable
    sarcolemma down T tubules
  • action potential affects SR

47
Neural Stimulation of Muscle Fibers
  • Step 5. Return to initial state.
  • AChE in cleft breaks down ACh
  • ACh unbinds from receptors
  • gated Na-channels close Na is pumped back out
    of sarcoplasm by Na-K ion pumps

48
Steps 1 5
49
Contraction Relaxation
  • Excitation-Contraction Coupling
  • action potential impulses cause release of Ca2
    from SR
  • Ca2 binds to F actin of myofibrils to initiate
    sarcomere contraction
  • continued reception of impulses causes continued
    contraction
  • Relaxation
  • Ca2 is reabsorbed by SR
  • sarcomeres cease contraction

50
Sarcomere Contraction Cycle
  • Step 1. Active site exposure.
  • Ca2 released from SR binds to troponin
  • troponin pulls tropomyosin away from active site
    on F actin
  • Step 2. Cross-bridge attachment.
  • myosin heads (cross-bridges) bind to exposed
    active sites of F actin

51
Sarcomere Contraction Cycle
  • Step 3. Pivoting of myosin head.
  • cocked myosin heads are bent away from M line
    due to stored energy from breakdown of ATP to ADP
    Pi
  • ADP Pi remain bound to heads in resting
    sarcomere
  • attachment of myosin head to active site of F
    actin releases stored energy to create a power
    stroke of head toward M line
  • ADP Pi are released as stroke occurs

52
Sarcomere Contraction Cycle
  • Step 4. Cross-bridge detachment.
  • ATP binds to myosin head following stroke
  • head unbinds from active site
  • exposed active site available for binding to next
    myosin head along length of myosin filament

53
Sarcomere Contraction Cycle
  • Step 5. Myosin reactivation.
  • ATP ? ADP Pi
  • released energy recockes myosin head
  • Cycle can now be repeated under
  • conditions
  • ? Ca2 maintained
  • ? ATP maintained

54
(No Transcript)
55
Observations of Sarcomere During Muscle
Contraction
sliding filament theory
56
Sarcomere Contraction
  • To View Video
  • Move mouse cursor over slide title-link
  • When hand appears, click once
  • MOV Video plays about 3-1/4 min

Additional Animation
57
Muscle Mechanics
  • Tension production
  • Energetics of muscular activity
  • Muscle performance

58
Learning Objectives
  • Muscle Contraction
  • Explain the all-or-nothing principle of muscle
    contraction
  • Discuss the structure function of a motor unit
  • Distinguish between isotonic isometric
    contraction
  • Energetics
  • Describe the mechanisms by which muscle fibers
    obtain the energy to power contractions

59
Muscle ContractionTension Production
  • All-or-None Principle
  • muscle fibers are either stimulated to the point
    of contraction or not
  • once stimulated, the entire muscle fiber
    contracts
  • Tension produced by whole skeletal muscle due to
  • frequency of stimulation
  • of fibers stimulated w/in muscle

60
Muscle ContractionMotor Unit
  • Motor unit
  • A single motor neuron all the muscle fibers
    controlled by it
  • Motor unit size
  • 4-6 fibers in eye muscles provide precise
    control of movement
  • 1000-2000 in leg muscles provide less precise
    control

61
Muscle ContractionMotor Unit
  • Recruitment
  • Smooth, steady increase in the number of motor
    units involved in a muscle contraction
  • a.k.a., multiple motor unit summation
  • Muscle tone
  • some motor units w/in a muscle are always active
  • switch off w/ resting units regularly to
    distribute activity

62
Isotonic Muscle Contraction
  • Isotonic contraction
  • Tension plateaus muscle changes length
  • concentric contraction
  • tension gt resistance muscle shortens
  • ex lifting weight
  • eccentric contraction
  • peak tension lt resistance muscle elongates
    due to contraction of another muscle or gravity
  • ex lowering weight

63
Isometric Muscle Contraction
  • Isometric contraction
  • tension varies but does not overcome resistance
  • muscle does not shorten
  • Note individual muscle fibers shorten until
    tendons are taught external tension internal
    tension generated by fibers
  • ex holding a weight stationary pushing
    against an immovable object

64
Charles Atlas
65
Muscle Relaxation Return to Resting Length
  • Causes of muscle relaxation
  • Recoil of stretched elastic fibers in perimyzium
  • Contractions of opposing muscles
  • Gravity

66
Energetics of Muscle Activity
  • ATP is produced by cellular respiration in muscle
    fibers
  • At rest, excess ATP energy stored as creatine
    phosphate (CP)
  • ATP creatine ?
  • ADP creatine phosphate

67
Energetics of Muscle Activity
  • During contraction myosin cross-bridges beak down
    ATP to ADP Pi
  • Energy stored as creatine phosphate (CP)
    recharges ADP
  • ADP creatine phosphate
  • ? ATP creatine

68
Aerobic Energy Metabolism O2 Present
  • Glycolysis
  • in cytosol of cytoplasm
  • C6H12O6 ? 2 pyruvate
  • yields 2 ATP (net)
  • Aerobic cellular respiration
  • in mitochondria
  • 2 pyruvate 6O2 ? 6CO2 6H2O
  • yields 25-34 ATP

69
Storage Compounds
OO
glycogen stores glucose
myoglobin stores O2
70
Anaerobic Energy Metabolism O2 Absent
  • Glycolysis
  • in cytosol of cytoplasm
  • C6H12O6 ? 2 pyruvate
  • yields 2 ATP (net)
  • Lactic acid fermentation
  • in cytosol
  • 2 pyruvate ? 2 lactic acid
  • yields 0 ATP

71
Muscle ActivityResting
Muscle ActivityModerate
Muscle ActivityStrenuous
72
Learning Objectives
  • Fiber Types
  • Relate the types of muscle fibers to muscle
    performance
  • Aerobic Anaerobic Endurance
  • Distinguish between aerobic anaerobic endurance
    explain their implications for muscle
    performance

73
Fiber Types Fast
  • Fast twitch muscle fibers
  • contract w/in 0.01 sec after stimulation
  • large diameter
  • densely packed myofibrils
  • reserves ? glycogen ? myoglobin
  • few mitochondria
  • Powerful contraction w/ rapid fatigue
  • deplete ATP reserves rapidly
  • activity supported by anaerobic metabolism
  • Pale reddish color

74
Fiber Types Slow
  • Slow twitch muscle fibers
  • contract w/in 0.03 sec after stimulation
  • small diameter
  • fewer myofibrils
  • reserves ? myoglobin ? lipid ? glycogen
  • many mitochondria
  • Moderate contraction w/ slow fatigue
  • deplete ATP reserves more slowly
  • activity supported by aerobic metabolism
  • Dark reddish color

75
Fiber Types Intermediate
  • Intermediate muscle fibers
  • properties intermediate btw/ fast twitch slow
    twitch
  • Pale reddish color
  • Note
  • Human muscles contain mixtures of 3 types
  • Content varies w/ genetics use

76
Muscle Size
  • Hypertrophy
  • increase in muscle mass
  • muscle fibers constant
  • diameter of muscle fibers ?
  • Atrophy
  • decrease in muscle mass
  • muscle fibers constant
  • diameter of muscle fibers ?

77
Anaerobic Endurance
  • Length of time muscular contraction can continue
    supported by glycolysis existing reserves of
    ATP CP
  • Limited by
  • Amount of ATP CP on hand
  • Amount of available glycogen
  • ability of muscle to tolerate lactic acid

78
Anaerobic Endurance
  • Training regimen
  • Frequent, short-duration exercise w/ intensive
    levels of muscular activity
  • Ex sprinting speed swimming weight lifting
    basketball

79
Aerobic Endurance
  • Length of time muscular contraction can continue
    supported by mitochondrial activity
  • Limited by
  • Amount of substrates from breakdown of
    carbohydrates, fatty acids, /or amino acids
  • Amount of available oxygen

80
Aerobic Endurance
  • Training regimen
  • Sustained, long duration exercise w/ low levels
    of muscular activity
  • Ex jogging cross country running distance
    swimming dance movements

81
Aging The Muscular System
  • Effects of aging on the bodys skeletal muscles
  • Effect of life style on aging of muscles

82
Learning Objectives
  • Aging
  • Specify 4 effects of aging on muscles
  • Discuss how regular exercise early in life can
    counter the effects of aging on the muscular
    system

83
Effects of Aging
  • Skeletal muscle fibers decrease in diameter
  • ? in myofibrils
  • Skeletal muscles lose elasticity
  • fibrosis ? collagen content
  • Tolerance for exercise decreases
  • ? thermoregulatory ability
  • ? rate of fatigue
  • Ability to recover from muscular injuries
    decreases
  • satellite cells ?
  • ? collagen content

84
Life Style Aging
  • Rate of decline in muscle performance is same for
    all individuals regardless of exercise patterns
    or lifestyle
  • To be in good shape late in life you must be
    in very good shape early in life
  • Regular, moderate exercise is more important than
    extremely demanding exercise

85
Integration With Other Systems
  • Dependence on other body systems
  • Responses of body systems to muscular activity

86
Learning Objectives
  • Integration
  • Discuss the interaction responses of 5 specific
    body systems to muscular activity

87
Integration Support From Other Body Systems
  • Cardiovascular System
  • ? heart rate dilation of blood vessels cause
  • ? O2 delivery CO2 removal
  • transports heat to skin for radiation to
    environment
  • Respiratory System
  • ? respiratory rate depth of respiration
  • ? O2 delivery CO2 removal
  • Integumentary System
  • dilation of blood vessels ? sweating
  • removes excess heat that would interfere w/
    muscle protein activity

88
Integration Support From Other Body Systems
  • Nervous System
  • controls voluntary muscle contraction
  • regulates/coordinates cardiovascular,
    respiratory, integumentary system activities
  • Endocrine System
  • regulates/coordinates cardiovascular,
    respiratory, integumentary system activities
  • maintains Ca2 -PO43- in blood other body
    fluids via skeletal, digestive, urinary systems

89
Integration Bones, Joints, Muscles
  • To View Video
  • Move mouse cursor over slide title-link
  • When hand appears, click once
  • ASX Video plays about 24 min
  • A Video Quiz is included in the presentation

90
Cardiac Muscle Tissue
  • Structural differences between cardiac skeletal
    muscle tissues
  • Functional differences between cardiac skeletal
    muscle tissues
  • The role of cardiac muscle in the body

91
Learning Objectives
  • Structure Function
  • Identify the structural functional differences
    between cardiac muscle tissue the other types
    of muscle tissue
  • Discuss the role that cardiac muscle plays in the
    cardiovascular system

92
CardiocytesStructural Organization
  • Single nucleus
  • Branched cellular structure
  • Striated myofibrils sarcomeres
  • T tubules short broad no triads
  • SR no terminal cisternae
  • Mitochondria ?
  • Intercalated discs btw/ adjacent cells
    transfer contractions from one cell to several
    others instantaneously

93
CardiocytesFunctional Features
  • Automaticity contraction w/out neural
    stimulation
  • pacemaker cells
  • Innervation alters pace of contraction
  • Duration of contraction 10 X longer
  • Sarcolemma characteristics prevent summation
    tetany
  • Dependent on aerobic metabolism ?
    mitochondria ? myoglobin

94
SmoothMuscle Tissue
  • Structural differences between smooth skeletal
    muscle tissues
  • Functional differences between smooth skeletal
    muscle tissues
  • The role of smooth muscle in body systems

95
Learning Objectives
  • Structure Function
  • Identify the structural functional differences
    between smooth muscle tissue the other types of
    muscle tissue
  • Discuss the role that smooth muscle plays in
    various body systems

96
Smooth Muscle CellsStructural Organization
  • Single nucleus
  • Spindle-shaped cellular structure
  • Non-striated no myofibrils or sarcomeres thick
    thin filaments scattered through cytoplasm
  • Dense body network attach to thin filaments
    to sarcolemma
  • No T tubules
  • SR loose network
  • Connective tissue sheaths do not unite to form
    tendons or aponeuroses

97
Smooth Muscle CellFunctional Features
  • Excitation-Contraction coupling Ca2 enter cell
    from extracellular fluid bind to calmodulin
    which activates myosin light chain kinase to
    break down ATP initiate contraction
  • Plasticity length-tension relationship allows
    for variable contraction length

98
Smooth Muscle CellFunctional Features
  • Control of contraction involuntary many cells
    not innervated respond to nearby smooth muscle
    cells
  • multiunit smooth muscle cells connected to 1 or
    more motor neurons leisurely contraction
  • loci iris of eye ? reproductive tract large
    arteries arrector pili muscles
  • visceral smooth muscle cells many lack direct
    neural contact
  • loci digestive tract urinary gall bladders
    many internal organs

smooth muscle sheet
99
The Muscular System
  • Introduction
  • Biomechanics Muscle Anatomy
  • Muscle Terminology
  • The Axial Muscles
  • The Appendicular Muscles

100
Introduction
  • Voluntary control
  • Form function
  • Factors determining the effects of contraction

101
Muscles
  • To View Video
  • Move mouse cursor over slide title-link
  • When hand appears, click once
  • ASX Video plays about 5 min

102
Learning Objectives
  • Muscle Control
  • Relate the muscular system to nervous control
  • Muscle Shape
  • Discuss how the structure of a muscle provides
    clues to its primary function
  • Effects of Muscle Contraction
  • Discuss 2 factors that interact to determine the
    effect of a muscles contraction

103
Voluntary Muscles
  • Muscular System
  • All muscles controlled voluntarily
  • 700 identified
  • 20 studied in book
  • 30 studied for course
  • Form function
  • locomotor muscles - stretch across joints
  • soft tissue support muscles - form sheets or
    slings
  • muscles guarding body entrances - form rings

104
Voluntary Muscles
  • Effects of contraction determined by
  • anatomical arrangement of muscle fibers
  • attachment points of muscle to bones

105
Biomechanics Muscle Anatomy
  • Organization of skeletal muscle fibers
  • Skeletal muscle length-tension relationships
  • Levers

106
Learning Objectives
  • Fascicles
  • Describe the arrangement of fascicles in the
    various types of muscles explain the resulting
    functional differences
  • Levers
  • Describe the different classes of levers how
    they make muscles more efficient

107
Organization of Skeletal Muscle Fibers
  • Fascicles
  • bundles of muscle fibers w/in a muscle
  • Patterns of fascicle organization
  • parallel muscles fascicles parallel to long
    axis of muscle
  • central body or belly w/ tendons at ends (most
    muscles)
  • some w/ broad attachments aponeuroses
  • Ex biceps brachii

108
Organization of Skeletal Muscle Fibers
  • Patterns of fascicle organization
  • convergent muscles fascicles begin over a broad
    area narrow to a single tendon or tendinous
    sheet
  • raphe some attach to band of collagen fibers
  • Ex pectoralis major

109
Organization of Skeletal Muscle Fibers
  • Patterns of fascicle organization
  • pennate muscles fascicles form common angle w/
    tendon
  • feather-shaped
  • unipennate all fascicles on same side of
    tendon Ex tensor digitorum
  • bipennate fascicles on both sides of
    tendon Ex rectus femoris
  • multipennate tendon fascicles branch Ex
    deltoid

110
Organization of Skeletal Muscle Fibers
  • Patterns of fascicle organization
  • circular muscles fascicles concentrically
    arranged around opening or recess
  • contraction ? decrease in diameter
  • Ex orbicularis oris

111
Fascicle Arrangements
112
Length-TensionRelationships
  • Muscles develop maximum tension over a narrow
    range of sarcomere length
  • stretched muscle less overlap of thick thin
    filaments in sarcomere
  • contracted muscle normal thick-thin filament
    relationship is disrupted
  • Ex when curling weights flexion is harder to
    achieve when arm muscles are stretched in
    extended arm, becomes easier as muscles contract,
    then harder after full flexion is achieved

113
Length-TensionRelationships
  • During complex movement muscles work in groups
  • smaller muscles aid larger muscles to reach
    length where maximum tension can be achieved

114
Levers
  • Lever rigid structure that moves on a fixed
    point called the fulcrum
  • In body, each bone is a lever each joint is a
    fulcrum
  • Lever action
  • change direction of an applied force
  • change distance speed of movement produced by
    applied force
  • change the effective strength of an applied force

115
Classes of Levers
  • First-class - fulcrum btw/ AF R
  • like see-saw
  • Ex muscles that extend neck
  • Second-class - R btw/ AF fulcrum
  • like loaded wheelbarrow
  • Ex calf muscles during plantar flexion
  • Third-class - AF btw/ R fulcrum
  • opposite of 2nd-class
  • most common lever action of body
  • Ex biceps brachii during flexion

116
Muscle Terminology
  • Origins insertions
  • Actions
  • Names of skeletal muscles
  • Divisions of the muscular system

117
Learning Objectives
  • Origins Insertions
  • Predict the actions of a muscle on the basis of
    the relative positions of its origin insertion
  • Movements
  • Explain how muscles interact to produce or oppose
    movements
  • Muscle Names
  • Explain how the name of a muscle can help
    identify its location, appearance, and/or function

118
Origins Insertions
  • Origin
  • beginning point of muscle attachment
  • usually remains stationary bone that moves
    little or not at all
  • usually proximal on limb
  • Insertion
  • end point of muscle attachment
  • usually moves bone that moves
  • usually distal on limb

119
Actions
  • Actions include flexion, extension, adduction,
    etc
  • In terms of bone affected
  • textbook ex flexion of the forearm
  • In terms of joint affected
  • professional ex flexion of the elbow

120
Primary Actions
  • Agonist
  • prime mover muscle chiefly responsible for a
    movement
  • Ex biceps brachii flexes elbow
  • Antagonist
  • prime mover muscle chiefly responsible for
    the opposite action of the agonist
  • Ex triceps brachii extends elbow

121
Primary Actions
  • Synergist
  • assists action of prime mover agonist or
    antagonist
  • aid in action of prime mover
  • fixator - stabilizes origin of prime mover by
    preventing competing movement at a joint

122
Naming Skeletal Muscles
  • Fascicle organization
  • rectus straight fascicles parallel to long
    axis of body
  • transversus across fascicles perpendicular to
    long axis of body
  • obliquus oblique fascicles angled to long axis
    of body
  • Location
  • brachii arm
  • femoris thigh

123
Naming Skeletal Muscles
  • Relative position
  • externus, extrinsic, superficialis outer body
    surface
  • internus, intrinsic, profundus beneath the body
    surface
  • Structure
  • biceps 2 tendons of origin
  • quadriceps 4 tendons of origin
  • Shape
  • deltoid triangular
  • orbicularis circular

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Naming Skeletal Muscles
  • Size length
  • longus longissimus long longest
    (respectively)
  • vastus large
  • teres long round
  • brevis short
  • magnus, major, maximus big, bigger, biggest
    (respectively)
  • minor minimus smaller smallest
    (respectively)

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Naming Skeletal Muscles
  • Position relative to body axis
  • anterior front
  • posterior back
  • lateralis toward side
  • medialis toward midline
  • Origin insertion
  • sternohyoid origin on sternum, insertion on
    hyoid bone

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Naming Skeletal Muscles
  • Action
  • flexor causes flexion
  • extensor, tensor causes extension
  • depressor causes lowering of body part
  • buccinator trumpeter (muscle that purses lips)
  • sartorius tailor-like (muscle that allows
    crossing of legs)

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Muscular System
  • Divisions of the Muscular System
  • axial musculature
  • positions head spinal column
  • moves rib cage
  • 60 of all muscles
  • appendicular musculature
  • stabilizes moves the arms legs
  • 40 of all muscles

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Axial Muscles
  • Muscles of the head neck
  • Muscles of the spine
  • Oblique rectus muscles
  • Muscles of the pelvic floor

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Learning Objectives
  • Axial Muscles
  • Identify the principal axial muscles of the body
    together with their origins, insertions, actions,
    innervation

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Muscles of theHead Neck
  • orbicularis oris
  • orbicularis oculi
  • oculomotor muscles
  • zygomaticus major minor
  • buccinator
  • masseter
  • sternocleidomastoid
  • platysma

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Muscles of the Face
132
Oculomotor Muscles
133
Muscles of the Torso
  • scalenes
  • external intercostals
  • internal intercostals
  • external oblique
  • rectus abdominis
  • diaphragm

134
Appendicular Muscles
  • Muscles of the shoulders upper limbs
  • Muscles of the lower limbs
  • Musculoskeletal compartments

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Learning Objectives
  • Appendicular Muscles
  • Identify the principal appendicular muscles of
    the body together with their origins, insertions,
    actions, innervation
  • Compare the major muscle groups of the upper
    lower limbs relate their differences to their
    functional roles

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Muscles of the Shoulder
  • trapezius
  • serratus anterior
  • pectoralis minor
  • pectoralis major
  • latissimus dorsi
  • deltoid

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Muscles of the Upper Limb
  • triceps brachii
  • biceps brachii
  • brachioradialis
  • brachialis
  • extensor muscles (general locus)
  • flexor muscles (general locus)

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Muscles of the Anterior Thigh
  • rectus femoris
  • vastus lateralis
  • vastus medialis
  • vastus intermedius
  • sartorius
  • gracilis

quadriceps femoris
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Muscles of theAnterior Thigh
140
Muscles of the Lateral Posterior Thigh
  • tensor fasciae latae
  • gluteus maximus
  • semitendinosis
  • biceps femoris
  • semimembranosis

hamstrings
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Muscles of the Lower Leg
  • gastocnemius
  • calcaneal tendon (Achilles tendon)
  • soleus
  • tibialis anterior
  • peroneus longus
  • peroneus brevis

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Muscles of theAnterior Lower Leg
143
Musculoskeletal Compartments
144
Muscular SystemOverview
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