163 ch 07_lecture_presentation
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© 2013 Pearson Education, Inc.
PowerPoint® Lecture Slidesprepared byMeg FlemmingAustin Community College
C H A P T E R
TheMuscular System
7
© 2013 Pearson Education, Inc.
Chapter 7 Learning Outcomes
• 7-1
• Specify the functions of skeletal muscle tissue.
• 7-2
• Describe the organization of muscle at the tissue level.
• 7-3
• Identify the structural components of a sarcomere.
• 7-4
• Explain the key steps involved in the contraction of a skeletal muscle fiber beginning at the neuromuscular junction.
• 7-5
• Compare the different types of muscle contractions.
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Chapter 7 Learning Outcomes
• 7-6
• Describe the mechanisms by which muscles obtain the energy to power contractions.
• 7-7
• Relate the types of muscle fibers to muscle performance, and distinguish between aerobic and anaerobic endurance.
• 7-8
• Contrast the structures and functions of skeletal, cardiac, and smooth muscle tissues.
• 7-9
• Explain how the name of a muscle can help identify its location, appearance, or function.
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Chapter 7 Learning Outcomes
• 7-10
• Identify the main axial muscles of the body together with their origins, insertions, and actions.
• 7-11
• Identify the main appendicular muscles of the body together with their origins, insertions, and actions.
• 7-12
• Describe the effects of aging on muscle tissue.
• 7-13
• Discuss the functional relationships between the muscular system and other organ systems.
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Five Skeletal Muscle Functions (7-1)
1. Produce movement of the skeleton • By pulling on tendons that then move bones
2. Maintain posture and body position
3. Support soft tissues • With the muscles of the abdominal wall and the pelvic floor
4. Guard entrances and exits • In the form of sphincters
5. Maintain body temperature • When contraction occurs, energy is used and converted to
heat
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Checkpoint (7-1)
1. Identify the five primary functions of skeletal
muscle.
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Organization of Skeletal Muscle Tissue (7-2)
• Skeletal muscles
• Are organs that contain:
• Connective tissue
• Blood vessels
• Nerves
• Skeletal muscle tissue
• Single skeletal muscle cells
• Also called skeletal muscle fibers
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Three Layers of Connective Tissue (7-2)
1. Epimysium
• Covers the entire muscle
2. Perimysium
• Divides the muscle into bundles called fascicles
• Blood vessels and nerves are contained in the
perimysium
3. Endomysium
• Covers each muscle fiber and ties fibers together
• Contains capillaries and nerve tissue
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Tendons (7-2)
• Where the ends of all three layers of connective
tissue come together
• And attach the muscle to a bone
• Aponeurosis
• A broad sheet of collagen fibers that connects muscles to
each other
• Similar to tendons, but do not connect to a bone
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Blood Vessels and Nerves (7-2)
• Extensive network of blood vessels in skeletal
muscle
• Provides high amounts of nutrients and oxygen
• To skeletal muscles which have high metabolic needs
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Control of Skeletal Muscle (7-2)
• Mostly under voluntary control
• Must be stimulated by the central nervous system
• Axons
• Push through the epimysium
• Branch through the perimysium
• And enter the endomysium
• To control individual muscle fibers
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Figure 7-1 The Organization of Skeletal Muscles.
Skeletal Muscle (organ)Epimysium Perimysium Endomysium Nerve
Musclefascicle
Musclefibers
Bloodvessels
Muscle Fascicle (bundle of fibers)
Perimysium
Muscle fiber
Endomysium
Epimysium
Blood vesselsand nerves
Endomysium
Perimysium
Tendon
Muscle Fiber (cell)Capillary Myofibril Endomysium
Sarcoplasm
MitochondrionStem cell
SarcolemmaNucleus
Axon of neuron
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Checkpoint (7-2)
2. Describe the connective tissue layers associated
with a skeletal muscle.
3. How would severing the tendon attached to a
muscle affect the muscle's ability to move a body
part?
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Features of Skeletal Muscle Fibers (7-3)
• Are specifically organized to produce contraction
and have specific names for general cell
structures
• Can be very long and are multinucleated
• Composed of highly organized structures, giving
them a striped or striated appearance
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The Sarcolemma and Transverse Tubules (7-3)
• The sarcolemma
• Specific name of muscle fiber plasma membrane
• Has openings across the surface that lead into a network of
transverse tubules, or T tubules
• T tubules allow for electrical stimuli to reach deep into each
fiber
• The sarcoplasm
• Specific name for muscle fiber cytoplasm
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Myofibrils in Muscle Fiber (7-3)
• Hundreds to thousands in each fiber
• Are encircled by T tubules and are as long as the
entire muscle fiber
• Are bundles of thick and thin myofilaments
• Actin molecules are found in thin filaments
• Myosin molecules are found in thick filaments
• Are the contractile proteins that shorten and are
responsible for contraction
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The Sarcoplasmic Reticulum (7-3)
• Or SR
• Specialized smooth endoplasmic reticulum
• Expanded end that is next to the T tubule is the
terminal cisternae
• Contain high concentrations of calcium ions
• Triad
• A combination of two terminal cisternae and one T tubule
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Sarcomeres (7-3)
• Smallest functional unit of skeletal muscle fiber
• Formed by repeating myofilament arrangements
• Each myofibril has about 10,000 sarcomeres
• Thick and thin filament arrangements are what
produce the striated appearance of the fiber
• Overlapping filaments define lines and bands
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Sarcomere Lines (7-3)
• Z lines
• Thin filaments at both ends of the sarcomere
• Another protein connects the Z lines to the thick filament to
maintain alignment
• M line
• Made of connections between the thick filaments
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Sarcomere Bands (7-3)
• A band
• Contains the thick filaments
• I band
• Contains the thin filaments, including the Z line
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Figure 7-2 The Organization of a Skeletal Muscle Fiber.
T tubules Terminalcisterna
Sarcoplasmicreticulum Triad Sarcolemma
Mitochondria
Thickfilament
MyofilamentsThin filament
MYOFIBRIL
The structure of a skeletalmuscle fiber.
SARCOMERE
Z line Zone of overlap
M line
Myofibril
I band H band
A band Zone of overlap
The organization of a sarcomere, part of a single myofibril.
Z line M line Z line
A stretched outsarcomere.
Z line and thinfilaments
Active site
Z line
Actin molecules Thick filaments
M line
ACTINSTRAND
Troponin TropomyosinThin filament
MYOSIN MOLECULE
Myosin tail
Myosinhead
Hinge
The structure of a thick filament.
The structure of a thin filament.
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Figure 7-2a The Organization of a Skeletal Muscle Fiber.
T tubules Terminalcisterna
Sarcoplasmicreticulum Triad Sarcolemma
Mitochondria
Thickfilament
MyofilamentsThin filament
MYOFIBRIL
The structure of a skeletalmuscle fiber.
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Figure 7-2b The Organization of a Skeletal Muscle Fiber.
Z line Zone of overlapM line
Myofibril
I band H band Zone of overlapA band
SARCOMERE
The organization of a sarcomere, part of a single myofibril.
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Figure 7-2c The Organization of a Skeletal Muscle Fiber.
Z line M line Z line
A stretched outsarcomere.
Z line and thinfilaments
Z line
Thick filaments
M line
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Figure 7-2d The Organization of a Skeletal Muscle Fiber.
Active site Actin molecules
ACTINSTRAND
Troponin Tropomyosin
Thin filament
The structure of a thin filament.
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Figure 7-2e The Organization of a Skeletal Muscle Fiber.
MYOSIN MOLECULE
Myosin tail
Myosinhead
Hinge
The structure of a thick filament.
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Thin and Thick Filaments (7-3)
• Actin
• A thin twisted protein, with specific active sites for myosin to
bind to
• At rest, active sites are covered by strands of tropomyosin,
held in position by troponin
• Myosin
• A thick filament with tail and globular head that attaches to
actin active sites during contraction
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Steps of Contraction (7-3)
1. Calcium released from SR
2. Calcium binds to troponin
3. Change of troponin shape causes tropomyosin to
move away from active sites
4. Myosin heads bind to active site, creating cross-
bridges, rotate and cause actin to slide over
myosin
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Sliding Filament Theory (7-3)
• Based on observed changes in sarcomere
• I bands get smaller
• Z lines move closer together
• H bands decrease
• A bands don't change, indicating that the thin filaments are
sliding toward the center
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Figure 7-3 Changes in the Appearance of a Sarcomere during Contraction of a Skeletal Muscle Fiber.
I band A band
Z line H band Z lineA relaxed sarcomere showinglocations of the A band, Z lines,and I band.
I band
During a contraction, the A band stays thesame width, but the Z lines move closertogether and the I band gets smaller.
Z line H band Z line
A band
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Checkpoint (7-3)
4. Describe the basic structure of a sarcomere.
5. Why do skeletal muscle fibers appear striated
when viewed through a light microscope?
6. Where would you expect the greatest
concentration of calcium ions to be in a resting
skeletal muscle fiber?
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The Neuromuscular Junction (7-4)
• Where a motor neuron communicates with a
skeletal muscle fiber
• Axon terminal of the neuron
• An enlarged end that contains vesicles of the
neurotransmitter
• Acetylcholine (ACh)
• The neurotransmitter that will cross the synaptic cleft
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The Neuromuscular Junction (7-4)
• ACh binds to the receptor on the motor end plate
• Cleft and the motor end plate contain
acetylcholinesterase (AChE)
• Which breaks down ACh
• Neurons stimulate sarcolemma by generating an
action potential
• An electrical impulse
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The cytoplasm of the axonterminal contains vesiclesfilled with molecules of ace-tylcholine, or ACh. Acetylcho-line is a neurotransmitter, achemical released by aneuron to change the perme-ability or other properties ofanother cell’s plasma mem-brane. The synaptic cleft andthe motor end plate containmolecules of the enzymeacetylcholinesterase (AChE),which breaks down ACh.
Vesicles ACh
Synaptic cleft
Motorend plate
AChE
Slide 1Figure 7-4 Skeletal Muscle Innervation.
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The stimulus for AChrelease is the arrival of anelectrical impulse, oraction potential, at theaxon terminal. The actionpotential arrives at theNMJ after traveling alongthe length of the axon.
Arriving actionpotential
Slide 2Figure 7-4 Skeletal Muscle Innervation.
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When the actionpotential reaches theneuron’s axon terminal,permeability changes inthe membrane trigger theexocytosis of ACh into thesynaptic cleft. Exocytosisoccurs as vesicles fusewith the neuron’s plasmamembrane.
Motor end plate
Slide 3Figure 7-4 Skeletal Muscle Innervation.
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ACh molecules diffuseacross the synaptic cleftand bind to ACh receptorson the surface of the motorend plate. ACh bindingalters the membrane’spermeability to sodiumions. Because the extracell-ular fluid contains a highconcentration of sodiumions, and sodium ionconcentration inside the cellis very low, sodium ionsrush into the sarcoplasm.
ACh receptor site
Slide 4Figure 7-4 Skeletal Muscle Innervation.
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The sudden inrush ofsodium ions results inthe generationof an action potentialin the sarcolemma.AChE quickly breaksdown the ACh on themotor end plate and inthe synaptic cleft, thusinactivating the AChreceptor sites.
Actionpotential
AChE
Slide 5Figure 7-4 Skeletal Muscle Innervation.
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The Contraction Cycle (7-4)
• Involves the triads
• Action potential travels over the sarcolemma,
down into the T tubules
• Causes release of calcium from the SR
• Calcium binds to troponin and the contraction
cycle starts
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Contraction CycleBegins
Myosin head
Troponin
ActinTropomyosin
Figure 7-5 The Contraction Cycle Slide 1
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Active-Site Exposure
Sarcoplasm
Activesite
Figure 7-5 The Contraction Cycle Slide 2
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Cross-Bridge Formation
Figure 7-5 The Contraction Cycle Slide 3
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Myosin Head Pivoting
Figure 7-5 The Contraction Cycle Slide 4
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Cross-BridgeDetachment
Figure 7-5 The Contraction Cycle Slide 5
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Myosin Reactivation
Figure 7-5 The Contraction Cycle Slide 6
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Table 7-1 Steps Involved in Skeletal Muscle Contraction and Relaxation
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Checkpoint (7-4)
7. Describe the neuromuscular junction.
8. How would a drug that blocks acetylcholine
release affect muscle contraction?
9. What would you expect to happen to a resting
skeletal muscle if the sarcolemma suddenly
became very permeable to calcium ions?
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Contraction Produces Tension (7-5)
• As sarcomeres contract, so does the entire muscle
fiber
• As fibers contract, tension is created by tendons
pulling on bones
• Movement will occur only if the tension is greater
than the resistance
• Compression is a force that pushes objects
• Muscle cells create only tension, not compression
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Contraction Produces Tension (7-5)
• Individual fibers
• Are either contracted or relaxed
• "On" or "off"
• Tension is a product of the number of cross-bridges a fiber
contains
• Variation in tension can occur based on:
• The amount of overlap of the myofilaments
• The frequency of stimulation
• The more frequent the stimulus, the more Ca2+ builds up,
resulting in greater contractions
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Contraction Produces Tension (7-5)
• Whole skeletal muscle organ
• Contracts with varying tensions based on:
• Frequency of muscle fiber stimulation
• Number of fibers activated
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A Muscle Twitch (7-5)
• A single stimulus-contraction-relaxation cycle in a
muscle fiber or whole muscle
• Represented by a myogram
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Three Phases of a Muscle Twitch (7-5)
1. Latent period
• Starts at the point of stimulus and includes the action potential,
release of Ca2+, and the activation of troponin/tropomyosin
2. Contraction phase
• Is the development of tension because of the cross-bridge
cycle
3. Relaxation phase
• Occurs when tension decreases due to the re-storage of Ca2+
and covering of actin active sites
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Figure 7-6 The Twitch and Development of Tension.
Maximum tensiondevelopment
Ten
sio
n
Stimulus
Time (msec) 0 5 10 20 30 40
Restingphase
Latentperiod
Contractionphase
Relaxationphase
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Summation and Tetanus (7-5)
• Summation
• Occurs with repeated, frequent stimuli that trigger a response
before full relaxation has occurred
• Incomplete tetanus
• Near peak tension with little relaxation
• Complete tetanus
• Stimuli are so frequent that relaxation does not occur
ANIMATION Frog Wave SummationPLAYPLAY
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Figure 7-7 Effects of Repeated Stimulations.
= Stimulus Maximum tension(in tetanus)
Time Time TimeSummation. Summationof twitches occurs whensuccessive stimuli arrivebefore the relaxation phasehas been completed.
Incomplete tetanus.Incomplete tetanus occursif the stimulus frequencyincreases further. Tensionproduction rises to a peak,and the periods ofrelaxation are very brief.
Complete tetanus.During complete tetanus,the stimulus frequency isso high that the relaxationphase is eliminated;tension plateaus atmaximal levels.
Ten
sio
n
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Varying Numbers of Fibers Activated (7-5)
• Allows for smooth contraction and a lot of control
• Most motor neurons control a number of fibers
through multiple, branching axon terminals
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Motor Unit (7-5)
• A single motor neuron and all the muscle fibers it
innervates
• Motor units are dispersed throughout the muscle
• Fine control movements
• Use motor units with very few fibers per neuron
• Gross movements
• Motor units have a high fiber-to-neuron ratio
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Recruitment (7-5)
• A mechanism for increasing tension to create
more movement
• A graded addition of more and more motor units to
produce adequate tension
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Figure 7-8 Motor Units.
Axons ofmotor neurons
SPINAL CORDMotornerve
Muscle fibersMotor unit 1
Motor unit 2
Motor unit 3
KEY
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Muscle Tone and Atrophy (7-5)
• Muscle tone
• Some muscles at rest will still have a little tension
• Primary function is stabilization of joints and posture
• Atrophy
• Occurs in a muscle that is not regularly stimulated
• Muscle becomes small and weak
• Can be observed after a cast comes off a fracture
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Types of Contraction (7-5)
• Isotonic contraction
• When the length of the muscle changes, but the tension
remains the same until relaxation
• For example, lifting a book
• Isometric contraction
• When the whole muscle length stays the same, the tension
produced does not exceed the load
• For example, pushing against a wall
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Elongation of Muscle after Contraction (7-5)
• No active mechanism for returning a muscle to a
pre-contracted, elongated state
• Passively uses a combination of:
• Gravity
• Elastic forces
• Opposing muscle movement
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Checkpoint (7-5)
10. What factors are responsible for the amount of
tension a skeletal muscle develops?
11. A motor unit from a skeletal muscle contains
1500 muscle fibers. Would this muscle be
involved in fine, delicate movements or in
powerful, gross movements? Explain.
12. Can a skeletal muscle contract without
shortening? Explain.
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ATP and CP Reserves (7-6)
• At rest, muscle cells generate ATP, some of which
will be held in reserve
• Some is used to transfer high energy to creatine
forming creatine phosphate (CP)
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ATP and CP Reserves (7-6)
• During contraction each cross-bridge breaks down ATP into ADP and a phosphate group • CP is then used to recharge ATP
• The enzyme creatine phosphokinase (CPK or CK) regulates this reaction • It lasts for about 15 seconds
• ATP must then be generated in a different way
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Aerobic Metabolism (7-6)
• Occurs in the mitochondria
• Using ADP, oxygen, phosphate ions, and organic substrates
from carbohydrates, lipids, or proteins
• Substrates go through the citric acid cycle
• A series of chemical reactions that result in energy to make
ATP, water, and carbon dioxide
• Oxygen supply decides ATP aerobic production
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Glycolysis (7-6)
• Breaks glucose down to pyruvate in the cytoplasm
of the cell
• If pyruvate can go through the citric acid cycle with
oxygen, it is very efficient
• Forming about 34 ATP
• With insufficient oxygen, pyruvate yields only 2
ATP
• Pyruvate is converted to lactic acid
• Potentially causing a pH problem in cells
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Figure 7-9 Muscle Metabolism.Fatty acids G Blood vessels
Glucose Glycogen
MitochondriaCreatine
Resting: Fatty acids are catabolized; the ATP producedis used to build energy reserves of ATP, CP, and glycogen.
Fatty acids
Glucose Glycogen
Pyruvate
2
2
34
34
To myofibrils to supportmuscle contraction
Moderate activity: Glucose and fatty acids are catabolized;the ATP produced is used to power contraction.
Lactate
Glucose Glycogen
PyruvateCreatine
2
2
To myofibrils to supportmuscle contraction
Peak activity: Most ATP is produced through glycolysis,with lactate and hydrogen ions as by-products. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed.
Lactate
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Figure 7-9a Muscle Metabolism.
Fatty acids Blood vessels
Glucose
G
Glycogen
MitochondriaCreatine
Resting: Fatty acids are catabolized; the ATP producedis used to build energy reserves of ATP, CP, and glycogen.
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Figure 7-9b Muscle Metabolism.
Fatty acids
Glucose Glycogen
Pyruvate
2
34
To myofibrils to supportmuscle contraction
34
2
Moderate activity: Glucose and fatty acids are catabolized;the ATP produced is used to power contraction.
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Peak activity: Most ATP is produced through glycolysis,with lactate and hydrogen ions as by-products. Mitochondrialactivity (not shown) now provides only about one-third of the ATP consumed.
Lactate
Glucose Glycogen
Pyruvate
Lactate
Creatine
To myofibrils to supportmuscle contraction
2
2
Figure 7-9c Muscle Metabolism.
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Muscle Fatigue (7-6)
• Caused by depletion of energy reserves or a
lowering of pH
• Muscle will no longer contract even if stimulated
• Endurance athletes, using aerobic metabolism,
can draw on stored glycogen and lipids
• Sprinters, functioning anaerobically, deplete CP
and ATP rapidly, and build up lactic acid
ANIMATION Frog FatiguePLAYPLAY
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The Recovery Period (7-6)
• Requires "repaying" the oxygen debt by continuing to
breathe faster
• Even after the end of exercise, and recycling lactic acid
• Heat production occurs during exercise
• Raising the body temperature
• Blood vessels in skin will dilate; sweat covers the skin and
evaporates
• Promoting heat loss
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Checkpoint (7-6)
13. How do muscle cells continuously synthesize
ATP?
14. What is muscle fatigue?
15. Define oxygen debt.
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Muscle Performance (7-7)
• Measured in force
• The maximum amount of tension produced by a muscle or
muscle group
• Measured in endurance
• The amount of time a particular activity can be performed
• Two keys to performance
1. Types of fibers in muscle
2. Physical conditioning or training
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Fast Fibers (7-7)
• The majority of muscle fibers in the body
• Large in diameter
• Large glycogen reserves
• Few mitochondria
• Rely on glycolysis
• Are rapidly fatigued
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Slow Fibers (7-7)
• About half the diameter of, and three times slower
than, fast fibers
• Are fatigue resistant because of three factors
1. Oxygen supply is greater due to more perfusion
2. Myoglobin stores oxygen in the fibers
3. Oxygen use is efficient due to large numbers of mitochondria
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Percentages of Muscle Types Vary (7-7)
• Fast fibers appear pale and are called white
muscles
• Extensive vasculature and myoglobin in slow
fibers cause them to appear reddish and are
called red muscles
• Human muscles are a mixture of fiber types and
appear pink
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Muscle Conditioning and Performance (7-7)
• Physical conditioning and training
• Can increase power and endurance
• Anaerobic endurance
• Is increased by brief, intense workouts
• Hypertrophy of muscles results
• Aerobic endurance
• Is increased by sustained, low levels of activity
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Checkpoint (7-7)
16. Why would a sprinter experience muscle fatigue
before a marathon runner would?
17. Which activity would be more likely to create an
oxygen debt in an individual who regularly
exercises: swimming laps or lifting weights?
18. Which type of muscle fibers would you expect
to predominate in the large leg muscles of
someone who excels at endurance activities
such as cycling or long-distance running?
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Cardiac Muscle Tissue (7-8)
• Found only in heart
• Cardiac muscle cells
• Relatively small with usually only one central nucleus
• Striated and branched
• Intercalated discs, which connect cells to other cells
• Communicate through gap junctions, allowing all the fibers to
work together
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Cardiac Pacemaker Cells (7-8)
• Exhibit automaticity
• Make up only 1 percent of myocardium
• Establish rate of contraction
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Cardiac Contractile Cells (7-8)
• 99 percent of myocardium
• Contract for longer period than skeletal muscle
fibers
• Unique sarcolemmas make tetanus impossible
• Are permeable to calcium
• Rely on aerobic metabolism
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Smooth Muscle Tissue (7-8)
• Found in the walls of most organs, in the form of
sheets, bundles, or sheaths
• Lacks myofibrils, sarcomeres, or striations
• Smooth muscle cells
• Also smaller than skeletal fibers
• Spindle-shaped and have a single nucleus
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Smooth Muscle Tissue (7-8)
• Thick filaments are scattered throughout
sarcoplasm
• Thin filaments are anchored to the sarcolemma
• Causing contraction to be like a twisting corkscrew
• Cells are bound together
• Resulting in forces being transmitted throughout the tissue
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Smooth Muscle Tissue (7-8)
• Different from other muscle types
• Calcium ions from the extracellular fluid are needed to trigger
a contraction mechanism that is different from other muscle
tissues
• Function involuntarily
• Can respond to hormones or pacesetter cells
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Figure 7-10 Cardiac and Smooth Muscle Tissues.
A light micrograph of cardiac muscle tissue.
Intercalateddiscs
Cardiacmuscle cell
Circularmuscle layer
Longitudinalmuscle layer
Many visceral organs contain several layers of smoothmuscle tissue oriented in different directions. Here, asingle sectional view shows smooth muscle cells inboth longitudinal (L) and transverse (T) sections.
Cardiac muscle tissue
Smooth muscle tissue
LM x 575
LM x 100
L
T
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Table 7-2 A Comparison of Skeletal, Cardiac, and Smooth Muscle Tissues
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Checkpoint (7-8)
19. How do intercalated discs enhance the
functioning of cardiac muscle tissue?
20. Extracellular calcium ions are important for the
contraction of what type(s) of muscle tissue?
21. Why can smooth muscle contract over a wider
range of resting lengths than skeletal muscle?
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Skeletal Muscle System Names (7-9)
• Based on:
• Action
• What they do
• Origin
• The end that stays stationary
• Insertion
• The end that moves
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Actions (7-9)
• Described as relative to the bone that is moved
• Example, "flexion of the forearm"
• Described as the joint that is involved
• Example, "flexion at the elbow"
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Primary Actions of Muscles (7-9)
• Prime mover, or agonist
• The muscle that is chiefly responsible for producing a movement
• Antagonist
• A muscle that opposes another muscle
• Synergist
• A muscle that helps the prime mover
• Example, flexion of the elbow
• The biceps brachii is the prime mover, the triceps brachii is the antagonist, and the brachialis is the synergist
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Table 7-3 Muscle Terminology (1 of 2)
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Table 7-3 Muscle Terminology (2 of 2)
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Muscle Terminology (7-9)
• Combining the various terms in Table 7-3,
anatomists name the muscles using:
• Location, direction of fibers, number of origins, and/or
function
• Muscles are organized into two groups
1. Axial muscles (mostly stabilizers)
2. Appendicular muscles (stabilizers or movers of the limbs)
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Figure 7-11a An Overview of the Major Skeletal Muscles.
Frontalis
Temporalis
Masseter
Sternocleidomastoid
TrapeziusClavicle
Deltoid
Pectoralis major
Biceps brachiiTriceps brachii
BrachialisPronator teres
Palmaris longusFlexor carpi radialis
Flexor digitorumTensor fasciae
latae
Vastus lateralisRectus femoris
PatellaTibia
Tibialis anteriorExtensor digitorum
SternumLatissimus dorsi Serratus anterior External oblique Rectus abdominis
Extensor carpi radialisBrachioradialisFlexor carpi ulnaris
GluteusmediusIliopsoas
Adductor longus GracilisSartoriusVastus medialis
FibularisGastrocnemiusSoleus
Anterior view
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Figure 7-11b An Overview of the Major Skeletal Muscles.
Sternocleidomastoid
TrapeziusDeltoid
InfraspinatusTeres minor
Latissimus dorsiBrachioradialisExtensor carpi
radialis
Occipitalis
Triceps brachii Rhomboid major
Flexor carpi ulnaris
External obliqueExtensor digitorum
Extensor carpi ulnarisGluteus medius
Gluteus maximusAdductor magnus SemimembranosusGracilisSartorius
Tensor fasciaelatae
SemitendinosusBiceps femoris
Gastrocnemius
Soleus
Calcanealtendon
Calcaneus
Teres major
Posterior view
© 2013 Pearson Education, Inc.
Checkpoint (7-9)
22. Identify the kinds of descriptive information used
to name skeletal muscles.
23. Which muscle is the antagonist of the biceps
brachii?
24. What does the name flexor carpi radialis longus
tell you about this muscle?
© 2013 Pearson Education, Inc.
Axial Muscles (7-10)
• Muscles of the head and neck
• Muscles of the spine
• Muscles of the trunk
• Muscles of the pelvic floor
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Muscles of the Head and Neck (7-10)
• Orbicularis oris • Constricts the mouth opening
• Buccinator • Compresses check to blow forcefully
• Masseter • Prime mover for chewing
• Temporalis and pterygoid • Synergists for chewing
• Digastric • Depresses the mandible
• Sternocleidomastoid • Rotates head or flexes neck
© 2013 Pearson Education, Inc.
Muscles of the Head and Neck (7-10)
• Epicranium, or scalp, contains a two-part muscle, the occipitofrontalis
1. Anterior frontalis
2. Posterior occipitalis
• Connected by epicranial aponeurosis
• Platysma
• Covers ventral neck extending from the base of the neck to the mandible
• Mylohyoid
• Supports the tongue
• Stylohyoid
1. Connects hyoid to styloid process
© 2013 Pearson Education, Inc.
Figure 7-12 Muscles of the Head and Neck.
Epicranialaponeurosis
(tendinous sheet)Frontalis
Orbicularisoculi
ZygomaticusOrbicularis oris
Depressoranguli oris
Temporalis
Occipitalis
BuccinatorMasseterSternocleidomastoid
Lateral pterygoidMedial pterygoid
Mandible
Platysma
Zygomaticus
Orbicularis oris
Platysma
Sternocleidomastoid
Platysma(cut and reflected)
Epicranialaponeurosis(tendinous sheet)
FrontalisTemporalis
Orbicularisoculi
MasseterBuccinator
Depressoranguli oris
Trapezius
Lateral view
Lateral view, pterygoidmuscles exposed Anterior view
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Figure 7-13 Muscles of the Anterior Neck.
Mylohyoid
Stylohyoid
Hyoid bone
Cartilagesof larynx
Sternothyroid
Sternohyoid
SternocleidomastoidCut heads of
sternocleidomastoid
Clavicle
Sternocleidomastoid(cut)
Digastric
MylohyoidMandible
Sternum
© 2013 Pearson Education, Inc.
Table 7-4 Muscles of the Head and Neck (1 of 2)
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Table 7-4 Muscles of the Head and Neck (2 of 2)
© 2013 Pearson Education, Inc.
Muscles of the Spine (7-10)
• Splenius capitis and semispinalis capitis
• Work together to either extend the head or tilt the head
• Erector spinae
• Are spinal extensors and include spinalis, longissimus, and
iliocostalis
• Quadratus lumborum
• Flex the spinal column and depress the ribs
© 2013 Pearson Education, Inc.
Figure 7-14 Muscles of the Spine.
Semispinalis capitis
Splenius capitis
Iliocostalis
Erectorspinaemuscles
Longissimus
Spinalis
Quadratuslumborum
© 2013 Pearson Education, Inc.
Table 7-5 Muscles of the Spine
© 2013 Pearson Education, Inc.
Axial Muscles of the Trunk (7-10)
• External and internal intercostals • Elevate and depress ribs, respectively
• Diaphragm • Muscle used for inhalation of breath
• External and internal obliques, and the transversus abdominis • Compress abdomen, can flex spine
• Rectus abdominis • Depresses ribs, flexes spine
© 2013 Pearson Education, Inc.
Figure 7-15 Oblique and Rectus Muscles and the Diaphragm.
Central tendonof diaphragm
Rectusabdominis
Xiphoidprocess
Externaloblique
Inferiorvena cava
T10
Erector spinae groupSpinal cord
Aorta
Diaphragm
Serratusanterior
Esophagus
Internalintercostal
Externalintercostal
Superior view at the levelof the diaphragm
Serratusanterior
Internal intercostal
External intercostal
External oblique(cut)
Internal oblique
Rectus abdominis
Anterior view
Linea alba(midline band
of denseconnective
tissue)
Aponeurosis
Externaloblique
Rectus abdominis
ExternalobliqueTransversusabdominisInternaloblique
Horizontal section view atthe level of the umbilicus
Quadratuslumborum
Linea alba
L3
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Table 7-6 Axial Muscles of the Trunk
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Muscles of the Pelvic Floor (7-10)
• Form the perineum and support the organs of the
pelvic cavity
• Flex the coccyx
• Control materials moving through the anus and
urethra with sphincters
© 2013 Pearson Education, Inc.
Figure 7-16 Muscles of the Pelvic Floor.
Superficial Dissections Deep Dissections
Urethra
Ischiocavernosus
External urethral sphincter
Bulbospongiosus
Central tendon of perineum
Vagina
Transverseperineus
Levator ani
External anal sphincter
Gluteus maximus
Female
Testis
No differences betweendeep musculature inmale and female
Urethra (connectingsegment removed)
IschiocavernosusBulbospongiosus
Transverseperineus
Anus
Gluteus maximus
External urethral sphincter
Central tendon of perineum
Levator ani
External anal sphincter
Male
Anus
© 2013 Pearson Education, Inc.
Table 7-7 Muscles of the Pelvic Floor
© 2013 Pearson Education, Inc.
Checkpoint (7-10)
25. If you were contracting and relaxing your masseter muscle, what would you probably be doing?
26. Which facial muscle would you expect to be well developed in a trumpet player?
27. Damage to the external intercostal muscles would interfere with what important process?
28. If someone were to hit you in your rectus abdominis, how would your body position change?
© 2013 Pearson Education, Inc.
Appendicular Muscles (7-11)
• Muscles that position the pectoral girdle
• Muscles that move the arm, forearm, and wrist
• Muscles that move the hand and fingers
• Muscles of the pelvic girdle
• Muscles that move the thigh and leg
• Muscles that move the foot and toes
© 2013 Pearson Education, Inc.
Muscles That Position Pectoral Girdle (7-11)
• Trapezius
• Diamond-shaped muscle, has many actions depending on the region
• Rhomboid
• Adducts and rotates scapula laterally
• Levator scapulae
• Adducts and elevates scapula
• Serratus anterior
• Abducts and rotates scapula
• Pectoralis minor and subclavius
• Depress and abduct shoulder
© 2013 Pearson Education, Inc.
Figure 7-17 Muscles That Position the Pectoral Girdle.
Superficial Dissection Deep Dissection
Muscles That Positionthe Pectoral Girdle
TrapeziusLevator scapulae
Rhomboid muscles
Serratus anterior
Tricepsbrachii
Posterior view
Trapezius Levator scapulae
SubclaviusPectoralis minor
Pectoralis major(cut and reflected)
Internal intercostals
External intercostals
Pectoralis minor(cut)Serratus anterior
Biceps brachii
Anterior view
Muscles That Positionthe Pectoral Girdle
Muscles That Positionthe Pectoral Girdle
Muscles That Positionthe Pectoral Girdle
Scapula
T12 vertebra
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Table 7-8 Muscles That Position the Pectoral Girdle
© 2013 Pearson Education, Inc.
Muscles That Move the Arm (7-11)
• Deltoid • Abducts arm, supraspinatus assists
• Subscapularis, teres major, infraspinatus, and teres minor • Form the rotator cuff
• Pectoralis major • Flexes the arm at the shoulder
• Latissimus dorsi • Extends the arm at the shoulder
A&P FLIX™ Rotator cuff muscles: An overview (b)PLAYPLAY
A&P FLIX™ Rotator cuff muscles: An overview (a)PLAYPLAY
© 2013 Pearson Education, Inc.
Figure 7-18 Muscles That Move the Arm.
Anterior view
Superficial Dissection Deep Dissection
Sternum
Clavicle Ribs (cut)
Muscles ThatMove the Arm
SubscapularisCoracobrachialisTeres major
Biceps brachii
Vertebra T12
Deltoid
Latissimus dorsi
SupraspinatusInfraspinatusTeres minorTeres major
Triceps brachii
Pectoralis major
Muscles ThatMove the Arm
Superficial Dissection Deep Dissection
Muscles ThatMove the Arm
SupraspinatusDeltoid
Muscles ThatMove the Arm
Posterior view
Vertebra T1
© 2013 Pearson Education, Inc.
Table 7-9 Muscles That Move the Arm
© 2013 Pearson Education, Inc.
Muscles That Move the Forearm and Wrist (7-11)• Biceps brachii
• Flexes the elbow and supinates forearm
• Triceps brachii • Extends elbow
• Brachialis and brachioradialis • Flex elbow
• Flexor carpi ulnaris, flexor carpi radialis, and palmaris longus • Flex wrist
• Extensor carpi radialis and extensor carpi ulnaris • Extend wrist
• Pronators and supinators • Rotate radius
© 2013 Pearson Education, Inc.
Muscles That Move the Hand (7-11)
• Extensor digitorum • Extends fingers
• Flexor digitorum • Flexes fingers
• Abductor pollicis • Abducts thumb
• Extensor pollicis • Extends thumb
A&P FLIX™ The elbow joint and forearm: An overviewPLAYPLAY
© 2013 Pearson Education, Inc.
Figure 7-19 Muscles That Move the Forearm and Wrist.
Triceps brachii
Brachioradialis
Extensorcarpi radialis
Extensorcarpi ulnaris Extensordigitorum Abductorpollicis
Extensorpollicis
Extensor retinaculum
Flexordigitorum
superficialis
Flexorretinaculum Pronator
quadratus
Flexor carpiulnaris
Palmaris longus
Humerus
Coracobrachialis
Biceps brachii
Pronator teres
Flexorcarpi
ulnaris
Ulna
Brachioradialis
Brachialis
Flexor carpiradialis
SupinatorPronator
teres
UlnaRadius
Posterior view of right upper limb
Anterior view of right upper limb
Anterior view of themuscles of pronationand supination whenthe limb is supinated
© 2013 Pearson Education, Inc.
Table 7-10 Muscles That Move the Forearm, Wrist, and Hand (1 of 2)
© 2013 Pearson Education, Inc.
Table 7-10 Muscles That Move the Forearm, Wrist, and Hand (2 of 2)
© 2013 Pearson Education, Inc.
Checkpoint (7-11)
29. Which muscle do you use to shrug your
shoulders?
30. Sometimes baseball pitchers suffer rotator cuff
injuries. Which muscles are involved in this type
of injury?
31. Injury to the flexor carpi ulnaris would impair
which two movements?
© 2013 Pearson Education, Inc.
Muscles That Move the Thigh (7-11)
• Gluteal group
• Includes gluteus maximus, the largest and most posterior; is a hip extensor
• Adductors
• Include the adductor magnus, adductor brevis, adductor longus, the pectineus, and the gracilis
• Largest hip flexor is the iliopsoas
• Made up of the psoas major and the iliacus
A&P FLIX™ Anterior muscles that cross the hip jointPLAYPLAY
© 2013 Pearson Education, Inc.
Figure 7-20 Muscles That Move the Thigh.
Iliac crestGluteus
medius (cut)Gluteus
maximus(cut)
SacrumGluteal Group
Gluteus maximusGluteus medius
Gluteus minimusTensor fasciae
lataeIliotibial tract
Vastus lateralis
Biceps femoris
SemimembranosusPlantaris
Head of fibula
Patella
PatellarligamentLateral
viewIliopsoas GroupPsoas major
Iliacus
PectineusAdductor brevisAdductor longus
Adductor magnusGracilis
Sartorius
Rectusfemoris
Gluteal region, posterior view
Adductor Group
Anterior view of the iliopsoas muscle and the adductor group
5L
© 2013 Pearson Education, Inc.
Table 7-11 Muscles That Move the Thigh (1 of 3)
© 2013 Pearson Education, Inc.
Table 7-11 Muscles That Move the Thigh (2 of 3)
© 2013 Pearson Education, Inc.
Table 7-11 Muscles That Move the Thigh (3 of 3)
© 2013 Pearson Education, Inc.
Muscles That Move the Leg (7-11)
• Knee flexors are the hamstrings
• Biceps femoris, semimembranosus, semitendinosus, and
the sartorius
• Knee extensors are the quadriceps femoris
• Which include the rectus femoris and the three vastus
muscles
• Popliteus muscle
• Unlocks the knee joint
© 2013 Pearson Education, Inc.
Figure 7-21 Muscles That Move the Leg.
Iliac crest
Gluteus medius
Tensor fasciaelatae
Gluteus maximus
Adductor magnus
Gracilis
Iliotibial tract
Flexors of the Knee
Biceps femoris
Semitendinosus
Semimembranosus
Sartorius
Popliteus
IliacusPsoas major Iliopsoas
Tensor fasciaelatae
Pectineus
Adductor longus
Gracilis
Sartorius
Extensors of the Knee(Quadriceps muscles)
Rectus femoris
Vastus lateralis
Vastus medialisVastus intermedius(deep to above muscles)
Quadriceps tendon
Patella
Patellar ligament
Hip and thigh, posterior view Quadriceps and thigh muscles, anterior view
© 2013 Pearson Education, Inc.
Table 7-12 Muscles That Move the Leg
© 2013 Pearson Education, Inc.
Muscles That Move the Foot and Toes (7-11)
• The gastrocnemius of the calf is assisted by the
underlying soleus
• They share a common calcaneal tendon, and are both
plantar flexors
• Fibularis muscles
• Produce eversion and plantar flexion
• Tibialis
• Cause inversion of the foot
• Tibialis anterior is largest and produces dorsiflexion
© 2013 Pearson Education, Inc.
Figure 7-22a Muscles That Move the Foot and Toes.
Superficial Dissection Deep Dissection
Ankle Extensors
Plantaris
Gastrocnemius
Soleus
Gastrocnemius(cut and removed)
Popliteus
Tendon of flexorhallucis longus
Calcanealtendon
Calcaneus
Head of fibula
Ankle Extensors(Deep)
Tibialis posterior
Fibularis longus
Fibularis brevis
Digital Flexors
Flexor digitorumlongus
Flexor hallucislongus
Tendon of flexor digitorumlongus
Tendons of fibularismuscles
Posterior views
© 2013 Pearson Education, Inc.
Iliotibial tract
Head of fibula
Ankle Extensors
Ankle FlexorsGastrocnemius
Fibularis longus
Soleus
Fibularis brevis
Tibialis anterior
Extensor digitorumlongus
Tendon of extensorhallucis longusCalcaneal tendon
Retinacula
Lateral view
Digital Extensors
Figure 7-22b Muscles That Move the Foot and Toes.
© 2013 Pearson Education, Inc.
Figure 7-22c Muscles That Move the Foot and Toes.
Patella
Patellarligament
Medial surfaceof tibial shaft
Ankle Extensors
Gastrocnemius
Soleus
Tibialis posterior
Calcaneal tendon
RetinaculaTendon of
tibialis anterior
Medial view
Ankle Flexors
Tibialis anterior
Tendon of extensorhallucis longus
Digital Extensors
© 2013 Pearson Education, Inc.
Table 7-13 Muscles That Move the Foot and Toes (1 of 2)
© 2013 Pearson Education, Inc.
Table 7-13 Muscles That Move the Foot and Toes (2 of 2)
© 2013 Pearson Education, Inc.
Checkpoint (7-11)
32. You often hear of athletes suffering a "pulled
hamstring." To what does this phrase refer?
33. How would you expect a torn calcaneal tendon
to affect movement of the foot?
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Four Effects of Aging on Skeletal Muscle (7-12)
1. Muscle fibers become smaller in diameter
2. Muscles become less elastic and more fibrous
3. Tolerance for exercise decreases due to a
decrease in thermoregulation
4. Ability to recover from injury is decreased
© 2013 Pearson Education, Inc.
Checkpoint (7-12)
34. Describe general age-related effects on skeletal
muscle tissue.
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Exercise Engages Multiple Systems (7-13)
• Cardiovascular system
• Increases heart rate and speeds up delivery of oxygen
• Respiratory system
• Increases rate and depth of respiration
• Integumentary system
• Dilation of blood vessels and sweating combine to increase cooling
• Nervous and endocrine systems
• Control of heart rate, respiratory rate, and release of stored energy
© 2013 Pearson Education, Inc.
Figure 7-23 SYSTEM INTEGRATORBody System Muscular System Muscular System Body System
Inte
gu
men
tary
Ske
leta
l
Removes excess body heat; synthesizes vitamin D3 for calcium and phosphate absorption; protects underlying muscles
Provides mineral reserve for maintaining normal calcium and phosphate levels in body fluids; supports skeletal muscles; provides sites of attachment
Skeletal muscles pulling on skin of face produce facial expressions
Inte
gu
men
tary
(Pag
e 1
38)
Provides movement and support; stresses exerted by tendons maintain bone mass; stabilizes bones and joints
Ske
leta
l(P
age
188
)
The MUSCULAR System
The muscular system performs five primary functions for the human body. It produces skeletal movement, helps maintain posture and body position, supports soft tissues, guards entrances and exits to the body, and helps maintain body temperature.
Ne
rvo
us
(Pag
e 3
02)
En
do
cri
ne
(Pag
e 3
76)
Car
dio
vasc
ula
r(P
age
467)
Ly
mp
hat
ic(P
age
500
)R
esp
ira
tory
(Pag
e 5
32)
Dig
esti
ve
(Pag
e 5
72)
Uri
na
ry(P
age
637
)R
ep
rod
uc
tiv
e(P
age
671
)
© 2013 Pearson Education, Inc.
Checkpoint (7-13)
35. What major function does the muscular system
perform for the body as a whole?
36. Identify the physiological effects of exercise on
the cardiovascular, respiratory, and
integumentary systems, and indicate the
relationship between these physiological effects
and the nervous and endocrine systems.