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PowerPoint® Lecture Slides
prepared by
Meg Flemming
Austin Community College
CHAPTER
7
The
Muscular
System
© 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.
© 2013 Pearson Education, Inc.
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.
© 2013 Pearson Education, Inc.
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.
© 2013 Pearson Education, Inc.
Intro to Muscular System video
• http://www.youtube.com/watch?v=aXdkzwJITsc
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Checkpoint (7-1)
1. Identify the five primary functions of skeletal
muscle.
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-1 The Organization of Skeletal Muscles.
Skeletal Muscle (organ)
Epimysium Perimysium Endomysium Nerve
Muscle Muscle Blood
fascicle fibers vessels
Muscle Fascicle (bundle of fibers)
Perimysium
Epimysium
Blood vessels
and nerves
Muscle fiber
Endomysium
Tendon
Endomysium
Muscle Fiber (cell)
Capillary Myofibril Endomysium
Sarcoplasm
Perimysium
Mitochondrion
Stem cell
Sarcolemma
Nucleus
Axon of neuron
© 2013 Pearson Education, Inc.
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?
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Sarcomere Bands (7-3)
• A band
• Contains the thick filaments
• I band
• Contains the thin filaments, including the Z line
© 2013 Pearson Education, Inc.
Figure 7-2 The Organization of a Skeletal Muscle Fiber.
Terminal Sarcoplasmic
T tubules cisterna
reticulum Triad
Sarcolemma
Mitochondria
Thick
filament
Thin
filament
Myofilaments
MYOFIBRIL
The structure of a skeletal
muscle fiber.
SARCOMERE
Z line
Zone of overlap
M line
Myofibril
H band
I band
Zone of overlap
A band
The organization of a sarcomere, part of a single myofibril.
M line
Z line
Z line
A stretched out
sarcomere.
M line
Z line
Z line and thin
filaments
Myosin
head
Thick filaments
Active site Actin molecules
Myosin tail
ACTIN
STRAND
Tropomyosin
Thin filament
The structure of a thin filament.
Troponin
© 2013 Pearson Education, Inc.
Hinge
MYOSIN MOLECULE
The structure of a thick filament.
Figure 7-2a The Organization of a Skeletal Muscle Fiber.
Terminal Sarcoplasmic
Triad Sarcolemma
T tubules cisterna
reticulum
Mitochondria
Thick
filament
Thin
filament
Myofilaments
MYOFIBRIL
The structure of a skeletal
muscle fiber.
© 2013 Pearson Education, Inc.
Figure 7-2b The Organization of a Skeletal Muscle Fiber.
SARCOMERE
Z line Zone of overlap M line
Myofibril
I band
H band
A band
The organization of a sarcomere, part of a single myofibril.
© 2013 Pearson Education, Inc.
Zone of overlap
Figure 7-2c The Organization of a Skeletal Muscle Fiber.
Z line
M line
Z line
A stretched out
sarcomere.
Z line
Z line and thin
filaments
© 2013 Pearson Education, Inc.
M line
Thick filaments
Figure 7-2d The Organization of a Skeletal Muscle Fiber.
Active site
Actin molecules
ACTIN
STRAND
Troponin
Tropomyosin
Thin filament
The structure of a thin filament.
© 2013 Pearson Education, Inc.
Figure 7-2e The Organization of a Skeletal Muscle Fiber.
Myosin
head
Myosin tail
MYOSIN MOLECULE Hinge
The structure of a thick filament.
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-3 Changes in the Appearance of a Sarcomere during Contraction of a Skeletal Muscle Fiber.
I band
Z line
A band
H band
Z line
A relaxed sarcomere showing
locations of the A band, Z lines,
and I band.
© 2013 Pearson Education, Inc.
I band
A band
H band
Z line
Z line
During a contraction, the A band stays the
same width, but the Z lines move closer
together and the I band gets smaller.
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?
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-4 Skeletal Muscle Innervation.
The cytoplasm of the axon
terminal contains vesicles
filled with molecules of acetylcholine, or ACh. Acetylcholine is a neurotransmitter, a
chemical released by a
neuron to change the permeability or other properties of
another cell’s plasma membrane. The synaptic cleft and
the motor end plate contain
molecules of the enzyme
acetylcholinesterase (AChE),
which breaks down ACh.
Vesicles
ACh
Synaptic cleft
Motor
end plate
© 2013 Pearson Education, Inc.
AChE
Slide 1
Figure 7-4 Skeletal Muscle Innervation.
Slide 2
The stimulus for ACh
release is the arrival of an
electrical impulse, or
action potential, at the
axon terminal. The action
potential arrives at the
NMJ after traveling along
the length of the axon.
Arriving action
potential
© 2013 Pearson Education, Inc.
Figure 7-4 Skeletal Muscle Innervation.
When the action
potential reaches the
neuron’s axon terminal,
permeability changes in
the membrane trigger the
exocytosis of ACh into the
synaptic cleft. Exocytosis
occurs as vesicles fuse
with the neuron’s plasma
membrane.
Motor
end plate
© 2013 Pearson Education, Inc.
Slide 3
Figure 7-4 Skeletal Muscle Innervation.
Slide 4
ACh molecules diffuse
across the synaptic cleft
and bind to ACh receptors
on the surface of the motor
end plate. ACh binding
alters the membrane’s
permeability to sodium
ions. Because the extracellular fluid contains a high
concentration of sodium
ions, and sodium ion
concentration inside the cell
is very low, sodium ions
rush into the sarcoplasm.
ACh receptor site
© 2013 Pearson Education, Inc.
Figure 7-4 Skeletal Muscle Innervation.
Slide 5
The sudden inrush of
sodium ions results in
the generation
of an action potential
in the sarcolemma.
AChE quickly breaks
down the ACh on the
motor end plate and in
the synaptic cleft, thus
inactivating the ACh
receptor sites.
Action
potential
AChE
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-5 The Contraction Cycle
Slide 1
Contraction Cycle
Begins
Myosin head
Troponin
Tropomyosin
© 2013 Pearson Education, Inc.
Actin
Figure 7-5 The Contraction Cycle
Slide 2
Active-Site Exposure
Sarcoplasm
Active
site
© 2013 Pearson Education, Inc.
Figure 7-5 The Contraction Cycle
Slide 3
Cross-Bridge Formation
© 2013 Pearson Education, Inc.
Figure 7-5 The Contraction Cycle
Slide 4
Myosin Head Pivoting
© 2013 Pearson Education, Inc.
Figure 7-5 The Contraction Cycle
Slide 5
Cross-Bridge
Detachment
© 2013 Pearson Education, Inc.
Figure 7-5 The Contraction Cycle
Slide 6
Myosin Reactivation
© 2013 Pearson Education, Inc.
Table 7-1 Steps Involved in Skeletal Muscle Contraction and Relaxation
© 2013 Pearson Education, Inc.
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?
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Contraction Produces Tension (7-5)
• Whole skeletal muscle organ
• Contracts with varying tensions based on:
• Frequency of muscle fiber stimulation
• Number of fibers activated
© 2013 Pearson Education, Inc.
A Muscle Twitch (7-5)
• A single stimulus-contraction-relaxation cycle in a
muscle fiber or whole muscle
• Represented by a myogram
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-6 The Twitch and Development of Tension.
Tension
Maximum tension
development
Stimulus
Time (msec) 0
5
10
Resting Latent Contraction
phase period
phase
© 2013 Pearson Education, Inc.
20
30
Relaxation
phase
40
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
PLAY
ANIMATION Frog Wave Summation
© 2013 Pearson Education, Inc.
Figure 7-7 Effects of Repeated Stimulations.
Maximum tension
(in tetanus)
Tension
= Stimulus
Time
Summation. Summation
of twitches occurs when
successive stimuli arrive
before the relaxation phase
has been completed.
© 2013 Pearson Education, Inc.
Time
Incomplete tetanus.
Incomplete tetanus occurs
if the stimulus frequency
increases further. Tension
production rises to a peak,
and the periods of
relaxation are very brief.
Time
Complete tetanus.
During complete tetanus,
the stimulus frequency is
so high that the relaxation
phase is eliminated;
tension plateaus at
maximal levels.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-8 Motor Units.
Axons of
motor neurons
Motor
nerve
KEY
Motor unit 1
Motor unit 2
Motor unit 3
© 2013 Pearson Education, Inc.
SPINAL CORD
Muscle fibers
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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.
© 2013 Pearson Education, Inc.
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)
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-9 Muscle Metabolism.
Fatty acids
G
Blood vessels
Glycogen
Glucose
Mitochondria
Creatine
Resting: Fatty acids are catabolized; the ATP produced
is used to build energy reserves of ATP, CP, and glycogen.
Fatty acids
Glucose
Glycogen
2
2
Pyruvate
34
34
To myofibrils to support
muscle contraction
Moderate activity: Glucose and fatty acids are catabolized;
the ATP produced is used to power contraction.
Lactate
Glycogen
Glucose
2
2
Pyruvate
Creatine
Lactate
To myofibrils to support
muscle contraction
© 2013 Pearson Education, Inc.
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.
Figure 7-9a Muscle Metabolism.
Fatty acids
G
Blood vessels
Glucose
Glycogen
Mitochondria
Creatine
Resting: Fatty acids are catabolized; the ATP produced
is used to build energy reserves of ATP, CP, and glycogen.
© 2013 Pearson Education, Inc.
Figure 7-9b Muscle Metabolism.
Fatty acids
Glucose
Glycogen
2
2
Pyruvate
34
34
To myofibrils to support
muscle contraction
Moderate activity: Glucose and fatty acids are catabolized;
the ATP produced is used to power contraction.
© 2013 Pearson Education, Inc.
Figure 7-9c Muscle Metabolism.
Lactate
Glucose
Glycogen
2
2
Pyruvate
Creatine
Lactate
To myofibrils to support
muscle 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.
© 2013 Pearson Education, Inc.
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
PLAY
ANIMATION Frog Fatigue
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Checkpoint (7-6)
13. How do muscle cells continuously synthesize
ATP?
14. What is muscle fatigue?
15. Define oxygen debt.
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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?
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Cardiac Pacemaker Cells (7-8)
• Exhibit automaticity
• Make up only 1 percent of myocardium
• Establish rate of contraction
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Figure 7-10 Cardiac and Smooth Muscle Tissues.
Cardiac
muscle cell
Intercalated
discs
Cardiac muscle tissue
LM x 575
A light micrograph of cardiac muscle tissue.
T
L
Circular
muscle layer
Longitudinal
muscle layer
Smooth muscle tissue LM x 100
© 2013 Pearson Education, Inc.
Many visceral organs contain several layers of smooth
muscle tissue oriented in different directions. Here, a
single sectional view shows smooth muscle cells in
both longitudinal (L) and transverse (T) sections.
Table 7-2 A Comparison of Skeletal, Cardiac, and Smooth Muscle Tissues
© 2013 Pearson Education, Inc.
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?
© 2013 Pearson Education, Inc.
Skeletal Muscle System Names (7-9)
• Based on:
• Action
• What they do
• Origin
• The end that stays stationary
• Insertion
• The end that moves
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Table 7-3 Muscle Terminology (1 of 2)
© 2013 Pearson Education, Inc.
Table 7-3 Muscle Terminology (2 of 2)
© 2013 Pearson Education, Inc.
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)
© 2013 Pearson Education, Inc.
Figure 7-11a An Overview of the Major Skeletal Muscles.
Frontalis
Temporalis
Trapezius
Clavicle
Deltoid
Masseter
Sternocleidomastoid
Pectoralis major
Sternum
Latissimus dorsi
Serratus anterior
External oblique
Rectus abdominis
Extensor carpi radialis
Brachioradialis
Flexor carpi ulnaris
Biceps brachii
Triceps brachii
Brachialis
Pronator teres
Palmaris longus
Flexor carpi radialis
Flexor digitorum
Tensor fasciae
latae
Vastus lateralis
Rectus femoris
Patella
Tibia
Tibialis anterior
Extensor digitorum
Gluteus
medius
Iliopsoas
Adductor longus
Gracilis
Sartorius
Vastus medialis
Fibularis
Gastrocnemius
Soleus
Anterior view
© 2013 Pearson Education, Inc.
Figure 7-11b An Overview of the Major Skeletal Muscles.
Sternocleidomastoid
Trapezius
Deltoid
Infraspinatus
Teres minor
Teres major
Latissimus dorsi
Brachioradialis
Extensor carpi
radialis
Tensor fasciae
latae
Semitendinosus
Biceps femoris
Gastrocnemius
Occipitalis
Triceps brachii
Rhomboid major
Flexor carpi ulnaris
External oblique
Extensor digitorum
Extensor carpi ulnaris
Gluteus medius
Gluteus maximus
Adductor magnus
Semimembranosus
Gracilis
Sartorius
Soleus
Calcaneal
tendon
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Calcaneus
Posterior view
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
• Connects hyoid to styloid process
© 2013 Pearson Education, Inc.
Figure 7-12 Muscles of the Head and Neck.
Epicranial
aponeurosis
(tendinous sheet)
Frontalis
Temporalis
Orbicularis
oculi
Occipitalis
Buccinator
Masseter
Sternocleidomastoid
Zygomaticus
Orbicularis oris
Depressor
anguli oris
Epicranial
aponeurosis
(tendinous sheet)
Frontalis
Temporalis
Orbicularis
oculi
Platysma
Lateral view
Zygomaticus
Orbicularis oris
Platysma
Sternocleidomastoid
Lateral pterygoid
Medial pterygoid
Mandible
Lateral view, pterygoid
muscles exposed
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Masseter
Buccinator
Depressor
anguli oris
Trapezius
Platysma
(cut and reflected)
Anterior view
Figure 7-13 Muscles of the Anterior Neck.
Mandible
Mylohyoid
Mylohyoid
Stylohyoid
Hyoid bone
Digastric
Sternocleidomastoid
(cut)
Cartilages
of larynx
Sternothyroid
Sternohyoid
Clavicle
Cut heads of
sternocleidomastoid
Sternocleidomastoid
Sternum
© 2013 Pearson Education, Inc.
Table 7-4 Muscles of the Head and Neck (1 of 2)
© 2013 Pearson Education, Inc.
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
Erector
Longissimus spinae
muscles
Spinalis
Quadratus
lumborum
© 2013 Pearson Education, Inc.
Table 7-5 Muscles of the Spine
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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.
Rectus Xiphoid
abdominis process
External
oblique
Inferior
vena cava
External
intercostal
Internal
intercostal
T10
Central tendon
of diaphragm
Esophagus
Serratus
anterior
Diaphragm
Aorta
Spinal cord
Erector spinae group
Superior view at the level
of the diaphragm
Rectus abdominis
Serratus
anterior
Internal intercostal
External
oblique
Aponeurosis
External intercostal
External oblique
(cut)
Internal oblique
Linea alba
(midline band
of dense
connective
tissue)
External
oblique
Transversus
abdominis
Internal
oblique
L3
Quadratus
lumborum
Rectus abdominis
Anterior view
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Linea alba
Horizontal section view at
the level of the umbilicus
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.
Deep Dissections
Superficial Dissections
Urethra
External urethral sphincter
Ischiocavernosus
Bulbospongiosus
Vagina
Transverse
perineus
Central tendon of perineum
Levator ani
Anus
External anal sphincter
Gluteus maximus
Female
No differences between
deep musculature in
male and female
Testis
Urethra (connecting
segment removed)
Ischiocavernosus
Bulbospongiosus
Transverse
perineus
Anus
External urethral sphincter
Central tendon of perineum
Levator ani
Gluteus maximus
External anal sphincter
Male
© 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 Position
the Pectoral Girdle
Trapezius
Muscles That Position
the Pectoral Girdle
Levator scapulae
Rhomboid muscles
Scapula
Serratus anterior
Triceps
brachii
Posterior view
Muscles That Position
the Pectoral Girdle
Trapezius
Levator scapulae
Subclavius
Pectoralis minor
Muscles That Position
the Pectoral Girdle
Pectoralis minor
(cut)
Serratus anterior
Pectoralis major
(cut and reflected)
Internal intercostals
Biceps brachii
External intercostals
Anterior view
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T12 vertebra
Table 7-8 Muscles That Position the Pectoral Girdle
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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
PLAY
A&P FLIX™ Rotator cuff muscles: An overview (a)
PLAY
A&P FLIX™ Rotator cuff muscles: An overview (b)
© 2013 Pearson Education, Inc.
Figure 7-18 Muscles That Move the Arm.
Deep Dissection
Superficial Dissection
Sternum
Clavicle
Ribs (cut)
Muscles That
Move the Arm
Deltoid
Pectoralis major
Muscles That
Move the Arm
Subscapularis
Coracobrachialis
Teres major
Biceps brachii
Vertebra T12
Anterior view
Deep Dissection
Superficial Dissection
Muscles That
Move the Arm
Supraspinatus
Deltoid
Latissimus dorsi
Vertebra T1
Muscles That
Move the Arm
Supraspinatus
Infraspinatus
Teres minor
Teres major
Triceps brachii
Posterior view
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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
PLAY
A&P FLIX™ The elbow joint and forearm: An overview
© 2013 Pearson Education, Inc.
Figure 7-19 Muscles That Move the Forearm and Wrist.
Humerus
Coracobrachialis
Triceps brachii
Biceps brachii
Brachioradialis
Extensor
carpi radialis
Brachialis
Flexor carpi
Extensor
radialis
carpi ulnaris
Flexor
Extensor
digitorum
digitorum
superficialis
Abductor
pollicis
Flexor
Extensor
retinaculum
pollicis
Extensor
retinaculum
Flexor
carpi
ulnaris
Ulna
Pronator teres
Brachioradialis
Palmaris longus
Flexor carpi
ulnaris
Pronator
quadratus
Supinator
Pronator
teres
Ulna
Radius
Posterior view of
right upper limb
© 2013 Pearson Education, Inc.
Anterior view of
right upper limb
Anterior view of the
muscles of pronation
and supination when
the limb is supinated
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
PLAY
A&P FLIX™ Anterior muscles that cross the hip joint
© 2013 Pearson Education, Inc.
Figure 7-20 Muscles That Move the Thigh.
Iliac crest
Gluteus
medius (cut)
Gluteus
maximus
(cut)
Sacrum
Gluteal region, posterior
view
Gluteal Group
Gluteus medius
Gluteus maximus
Gluteus minimus
Tensor fasciae
latae
Iliotibial tract
Vastus lateralis
Sartorius
Rectus
femoris
Biceps femoris
Semimembranosus
Plantaris
Head of fibula
L5
Patella
Patellar
Lateral ligament
view
Iliopsoas Group
Psoas major
Iliacus
Adductor Group
Pectineus
Adductor brevis
Adductor longus
Adductor magnus
Gracilis
Anterior view of the
iliopsoas muscle and
the adductor group
© 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 fasciae
latae
Gluteus maximus
Iliacus
Psoas major
Iliopsoas
Tensor fasciae
latae
Pectineus
Adductor longus
Gracilis
Adductor magnus
Sartorius
Gracilis
Iliotibial tract
Flexors of the Knee
Extensors of the Knee
(Quadriceps muscles)
Rectus femoris
Biceps femoris
Vastus lateralis
Semitendinosus
Vastus medialis
Vastus intermedius
(deep to above muscles)
Semimembranosus
Quadriceps tendon
Sartorius
Patella
Popliteus
Patellar ligament
Hip and thigh, posterior view
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Quadriceps and thigh muscles, anterior view
Table 7-12 Muscles That Move the Leg
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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
Head of fibula
Gastrocnemius
Soleus
Popliteus
Ankle Extensors
(Deep)
Tibialis posterior
Fibularis longus
Fibularis brevis
Digital Flexors
Gastrocnemius
(cut and removed)
Flexor digitorum
longus
Flexor hallucis
longus
Calcaneal
tendon
Tendon of flexor
hallucis longus
Calcaneus
Tendons of fibularis
muscles
Posterior views
© 2013 Pearson Education, Inc.
Tendon of flexor digitorum
longus
Figure 7-22b Muscles That Move the Foot and Toes.
Iliotibial tract
Head of fibula
Ankle Extensors
Gastrocnemius
Ankle Flexors
Fibularis longus
Tibialis anterior
Soleus
Fibularis brevis
Digital Extensors
Extensor digitorum
longus
Tendon of extensor
hallucis longus
Calcaneal tendon
Retinacula
Lateral view
© 2013 Pearson Education, Inc.
Figure 7-22c Muscles That Move the Foot and Toes.
Patella
Medial surface
of tibial shaft
Patellar
ligament
Ankle Flexors
Ankle Extensors
Tibialis anterior
Gastrocnemius
Soleus
Digital Extensors
Tibialis posterior
Tendon of extensor
hallucis longus
Calcaneal tendon
Retinacula
Tendon of
tibialis anterior
Medial view
© 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?
© 2013 Pearson Education, Inc.
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.
© 2013 Pearson Education, Inc.
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.
SYSTEM INTEGRATOR
Skeletal
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
Muscular System
Body System
Skeletal muscles pulling on skin of
face produce facial expressions
Provides movement and support;
stresses exerted by tendons maintain
bone mass; stabilizes bones and
joints
(Page 138)
Muscular System
Integumentary
Integumentary
Body System
Skeletal
(Page 188)
Figure 7-23
Endocrine
(Page 376)
Reproductive
(Page 671)
Urinary
(Page 637)
Digestive
(Page 572)
Respiratory
(Page 532)
Lymphatic
(Page 500)
Cardiovascular
(Page 467)
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.
Nervous
(Page 302)
The MUSCULAR System
© 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.
© 2013 Pearson Education, Inc.