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PowerPoint® Lecture Slides
prepared by
Betsy C. Brantley
Valencia College
CHAPTER
6
The Muscular
System
© 2013 Pearson Education, Inc.
Chapter 6 Learning Outcomes
• Section 1: Functional Anatomy of Skeletal Muscle Tissue
• 6.1
• Describe the organization of skeletal muscle at the tissue level.
• 6.2
• Identify the structural components of a sarcomere and
differentiate between thin filaments and thick filaments.
• 6.3
• Identify the components of the neuromuscular junction, and
summarize the events involved in the neural control of skeletal
muscle fibers.
• 6.4
• Describe the sliding filament theory.
© 2013 Pearson Education, Inc.
Chapter 6 Learning Outcomes
• 6.5
• Describe the role of ATP in a muscle contraction, and explain
the steps involved in the contraction of a skeletal muscle fiber.
• Section 2: Functional Properties of Skeletal Muscle Tissue
• 6.6
• Describe the mechanism responsible for producing tension in a
muscle fiber and discuss the factors that affect peak tension
during skeletal muscle contraction.
• 6.7
• Explain the role of motor units in the production of muscle
tension.
© 2013 Pearson Education, Inc.
Chapter 6 Learning Outcomes
• 6.8
• Compare and contrast isotonic contraction and isometric
contraction.
• 6.9
• Describe how ATP is produced in muscles during rest,
moderate activity, and peak activity.
• 6.10
• CLINICAL MODULE Explain the physiological factors involved
with muscle hypertrophy, atrophy, paralysis, and rigor mortis.
• Section 3: Functional Organization of the Muscular System
• 6.11
• Explain how the name of a muscle can help identify its location,
appearance, or function.
© 2013 Pearson Education, Inc.
Chapter 6 Learning Outcomes
• 6.12
• Describe flexion, extension, abduction, adduction, and
circumduction as movements of the body.
• 6.13
• Describe rotation and special movements of the body.
• 6.14
• Describe the separation of muscles into axial and appendicular
divisions and identify key muscles in each division.
• 6.15
• Identify the main muscles of the head and neck, along with their
origins, insertions, and actions.
• 6.16
• Identify the main muscles of the vertebral column, along with
their origins, insertions, and actions.
© 2013 Pearson Education, Inc.
Chapter 6 Learning Outcomes
• 6.17
• Identify the main muscles of the trunk, along with their origins,
insertions, and actions.
• 6.18
• Identify the main appendicular muscles of the trunk, along with
their origins, insertions, and actions.
• 6.19
• Identify the main muscles of the arm, forearm, and fingers,
along with their origins, insertions, and actions.
• 6.20
• Identify the main muscles that move the leg, along with their
origins, insertions, and actions.
• 6.21
• Identify the main muscles that move the foot and toes, along
with their origins, insertions, and actions.
© 2013 Pearson Education, Inc.
Muscle Tissue (Section 1)
• One of the four primary tissue types
• Specialized for contraction
• Three types
1. Skeletal muscle tissue
2. Cardiac muscle tissue
3. Smooth muscle tissue
© 2013 Pearson Education, Inc.
Types of muscle tissue
Skeletal Muscle Tissue
Cardiac Muscle Tissue
Smooth Muscle Tissue
© 2013 Pearson Education, Inc.
Figure 6 Section 1 1
Muscle Tissue Types (Section 1)
• Skeletal muscle
• Moves the body by pulling on bones of skeleton
• Cardiac muscle
• Found only in the heart
• Propels blood
• Smooth muscle
• Moves fluid and solids along digestive tract
• Regulates diameter of small arteries
© 2013 Pearson Education, Inc.
Skeletal Muscle Tissue Functions (Section 1)
• Produce skeletal movement
• Muscle contractions pull on tendons, moving bones of
skeleton
• Maintain body posture and body position
• Constant muscle activity maintains tension in skeletal muscle
• Support soft tissue
• Layers of skeletal muscle form abdominal wall and floor of
pelvic cavity
• Support weight of visceral organs and protect internal tissues
© 2013 Pearson Education, Inc.
Skeletal Muscle Tissue Functions (Section 1)
• Guard entrances and exits
• Skeletal muscles encircle openings to digestive and urinary
tracts, forming sphincters
• Provide voluntary control over swallowing, defecation, and
urination
• Maintain body temperature
• Muscle contraction requires energy and produces heat in
process
• Provide nutrient reserves
• Contractile proteins in skeletal muscle broken down to amino
acids when intake of protein or calories is inadequate
• Amino acids used to synthesize glucose and to provide
energy
© 2013 Pearson Education, Inc.
Skeletal Muscle Structure (6.1)
• Skeletal muscle is a bundle of skeletal muscle fibers wrapped in
connective tissue layers
• Epimysium
• Dense layer of collagen fibers surrounding entire muscle
• Perimysium
• Fibrous layer dividing skeletal muscle into bundles of fibers
called muscle fascicles
• Endomysium
• Delicate connective tissue surrounding individual muscle fibers
© 2013 Pearson Education, Inc.
Tendons (6.1)
• Collagen fibers of connective tissue layers in
skeletal muscle extend beyond muscle at end
• Bundle of fibers is tendon
• Tendon attaches muscle to bone
• Sheet of fibers is aponeurosis
• Aponeurosis attaches muscle to broader area
• Collagen fibers extend into bone matrix
© 2013 Pearson Education, Inc.
Organization of skeletal muscle
Endomysium Epimysium wrapped
Muscle
around muscle
Perimysiumfascicle
Nerve
Muscle fibers
Blood vessels
Muscle fiber
Epimysium
Blood vessels
and nerves
Perimysium
wrapped around
muscle fascicle
Endomysium
Myofibril (fine
contractile fiber)
Tendon (bundle of
collagen fibers of the
connective tissue
layers)
Axon of
neuron
© 2013 Pearson Education, Inc.
Endomysium
wrapped around a
muscle fiber
Stem cells
Capillary
Figure 6.1 1 -12 – 3
Skeletal Muscle Fiber Terminology (6.1)
• Muscle cell is muscle fiber
• Cell membrane is sarcolemma
• Cytoplasm is sarcoplasm
• Endoplasmic reticulum (ER) is sarcoplasmic
reticulum (SR)
© 2013 Pearson Education, Inc.
Skeletal Muscle Fiber Structure (6.1)
• Muscle fibers
• Contain hundreds of nuclei
• Filled with cylindrical structures called myofibrils
• Packed with myofilaments
• Thin filaments composed mostly of actin
• Thick filaments composed primarily of myosin
• Banded appearance of myofibrils gives entire fiber
striated look
© 2013 Pearson Education, Inc.
Structure of a skeletal muscle fiber
Nuclei
Myofibrils
Sarcoplasm
Mitochondria
Sarcolemma
Skeletal muscle fiber
Myofibril
Nuclei
Sarcolemma
Sarcoplasm
Sarcolemma
Myofibril
Thin filament
Thick filament
Mitochondria Sarcoplasmic reticulum
© 2013 Pearson Education, Inc.
Figure 6.1 1 -42 – 6
Module 6.1 Review
a. Define tendon and aponeurosis.
b. Describe the connective tissue layers associated
with skeletal muscle tissues.
c. Explain the relationship between muscle fibers,
myofibrils, and myofilaments.
© 2013 Pearson Education, Inc.
Sarcomeres (6.2)
• Functional unit of skeletal muscle fiber, about 10,000 per
myofibril
• Z lines
• Boundary between adjacent sarcomeres
• M line
• Connects central part of each thick filament
• H band
• Lighter band; contains only thick filaments
• A band
• Darker band; contains thick and thin filaments
• I band
• Lighter band; contains only thin filaments
© 2013 Pearson Education, Inc.
Sarcomere structure
M line
A band
I band
Myofibril
Sarcomere
H band
© 2013 Pearson Education, Inc.
Z lines
In the zone of overlap,
thin filaments are interspersed
among the thick filaments.
Figure 6.2 11
Structure of Thin Filaments (6.2)
• Attached to Z lines at each end
• Composed of three proteins
• Actin – makes up most of the thin filament as a twisted
double strand
• Contains binding sites for myosin
• Tropomyosin
• Covers myosin binding sites on actin when muscle relaxed
• Troponin
• Binds to tropomyosin and actin keeping complex in place
• Also has binding site for calcium
© 2013 Pearson Education, Inc.
Structure of thin filaments
Active site
Z line
Thin filament
Actin molecules Tropomyosin
© 2013 Pearson Education, Inc.
Troponin has binding
sites for tropomyosin,
actin, and calcium.
Figure 6.2 12
Structure of Thick Filaments (6.2)
• Contains about 300 myosin molecules
• Arranged with myosin tails pointing toward M line
• Myosin head
• Two protein subunits
• During contraction, head attaches to actin in thin filament,
forming cross-bridges
• Elastic core of thick filament recoils after stretching
• Keeps thick and thin filaments aligned
© 2013 Pearson Education, Inc.
Structure of thick filaments
Elastic core of
thick filament
Thick filament M line
Myosin molecule
Myosin tail binds to
other myosin molecules
© 2013 Pearson Education, Inc.
Myosin head
Hinge at the connection
between tail and head
Figure 6.2 13
Sarcolemma and T-tubules (6.2)
• Uneven charge distribution on either side of
sarcolemma called membrane potential
• Sudden change in membrane potential (first step
in muscle contraction) travels along transverse
tubules (T-tubules)
• Continuous with sarcolemma; at right angles to surface
• Form passageways through muscle fiber
• Encircle sarcomere and tightly bound to sarcoplasmic
reticulum
© 2013 Pearson Education, Inc.
Sarcoplasmic Reticulum (6.2)
• Tubular network around each myofibril
• Enlarged sections on either side of T-tubule
• Contains calcium ions
• Beginning of muscle contraction
• Change in membrane potential of T-tubule
• Triggers release of calcium ions from sarcoplasmic
reticulum into sarcoplasm
© 2013 Pearson Education, Inc.
Sarcoplasmic reticulum and transverse tubules
Sarcolemma
Sarcoplasmic
reticulum
Transverse tubules (T tubules)
© 2013 Pearson Education, Inc.
Position of M line
T tubules tightly bound
to sarcoplasmic reticulum
Figure 6.2 14
Module 6.2 Review
a. In a sarcomere, what is the zone of overlap?
b. Describe the components of thin and thick
filaments.
c. The sarcoplasmic reticulum is similar to what
structure in other cells?
© 2013 Pearson Education, Inc.
Skeletal Muscle Fiber Contraction (6.3)
1. Nervous signal (action potential) from motor
neuron travels down axon to neuromuscular
junction (NMJ)
•
NMJ where axon terminal is near motor end plate on
skeletal muscle fiber
2. Neurotransmitter, acetylcholine (ACh) held in
vesicles in axon terminal
•
Acetylcholinesterase (AChE), which breaks down ACh, is
found in synaptic cleft and on sarcolemma
© 2013 Pearson Education, Inc.
Skeletal Muscle Fiber Contraction (6.3)
3. Action potential (change in membrane
potential) stimulus for release of acetylcholine
from vesicles in axon terminal
4. In response to action potential, axon terminal
membrane changes permeability, triggering
release of ACh into synaptic cleft
© 2013 Pearson Education, Inc.
Skeletal Muscle Fiber Contraction (6.3)
5. ACh diffuses across synaptic cleft
•
ACh binds to ACh receptors on motor end plate of muscle
fiber
•
Binding changes membrane permeability to sodium
•
Sodium ions rush into muscle fiber sarcoplasm
6. Rush of positive sodium ions into sarcoplasm
generates action potential on sarcolemma
•
AChE breaks down ACh in synaptic cleft, inactivating ACh
receptors
© 2013 Pearson Education, Inc.
Skeletal Muscle Fiber Contraction (6.3)
7. Action potential moves across entire sarcolemma
8. Action potential moves down T-tubules
• T-tubules between terminal cisternae of
sarcoplasmic reticulum (SR)
• Action potential in T-tubule causes release of
calcium from SR, triggering muscle fiber contraction
© 2013 Pearson Education, Inc.
Skeletal muscle stimulation by a motor neuron
Vesicles
Synaptic cleft containing
ACh (red)
Motor end plate with
ACh receptors
Arriving action
potential
AChE
ACh
receptor
Motor
end plate
Motor
end plate
ACh
receptor
Motor end plate
Axon terminal
Sarcoplasmic
reticulum
Action
potential
Myofibril
Motor
neuron
Sarcolemma of
motor end plate
Path of electrical
impulse (action
potential)
Axon
Neuromuscular
junction
T tubule
SarcoMyofibril plasm
Motor end plate
© 2013 Pearson Education, Inc.
AChE
Sarcoplasmic
reticulum (SR)
Figure 6.3 1
Module 6.3 Review
a. Describe the neuromuscular junction.
b. How would a drug that blocked acetylcholine
release affect muscle contraction?
c. Predict what would happen if there were no
AChE in the synaptic cleft.
© 2013 Pearson Education, Inc.
Sliding Filament Theory (6.4)
• Thin filaments slide past thick filaments
• H bands and I bands get smaller
• Zones of overlap get larger
• Z lines move closer together
• A bands remain constant
© 2013 Pearson Education, Inc.
Changes in a sarcomere during contraction
Z line
I band
A band
I band
Zone of
overlap
Sarcomere at rest
© 2013 Pearson Education, Inc.
H band
Z line
A band
H band Zone of Z line
overlap
Sarcomere contraction and filament sliding
Z line
Figure 6.4 11
Muscle Fiber Shortens (6.4)
• Overall sarcomere length decreases
• Myofibrils shorten
• Muscle fiber shortens
• Filaments do not change length
© 2013 Pearson Education, Inc.
Myofibril changes during contraction
Myofibril at rest
Contracted Myofibril
Myofibril at rest
Fixed
end
Contracted Myofibril
© 2013 Pearson Education, Inc.
Figure 6.4 12
Tension Transmitted to Bone (6.4)
• Myofilaments attached to end of muscle fiber
• Muscle fibers attached to tendons attached to
bone
• Sarcomere contraction reflected out to entire
skeletal muscle
• Result is movement of bone
© 2013 Pearson Education, Inc.
Muscle fibers are attached to tendons
Epimysium
Myofibrils
Endomysium
Muscle fiber
Tendon
Perimysium
© 2013 Pearson Education, Inc.
Figure 6.4 13
Returning Muscles to Original Length (6.4)
• Contraction is an active process
• ATP used as power source
• Strength of contraction depends on how many muscle fibers
in muscle are active
• No active process to lengthen muscles
• Return to original length by:
• Gravity
• Contraction of opposite muscle
• Elasticity in tissues stretched by contraction
© 2013 Pearson Education, Inc.
Muscles work in pairs
Triceps
muscle
contracts
Biceps
muscle
relaxes
During a contraction, a
particular muscle or group
of muscles is stimulated, and
any opposing muscles relax.
Opposing muscle
(triceps) relaxes
Biceps muscle
contracts
© 2013 Pearson Education, Inc.
Figure 6.4 1 -42 – 5
Module 6.4 Review
a. Define the sliding filament theory.
b. Summarize the changes a sarcomere undergoes
during a contraction.
c. If there is no active mechanism for lengthening a
muscle, how does a muscle regain its initial
length after a contraction?
© 2013 Pearson Education, Inc.
Myosin Position at Rest (6.5)
• At rest, myosin head is energized pointing away
from M line
• Energy to put myosin head in "cocked" position
from ATP breakdown
• ADP and phosphate (P) still bound to myosin head
© 2013 Pearson Education, Inc.
Contraction Cycle (6.5)
1. Contraction cycle begins
•
Calcium ions arrive in zone of overlap
2. Active sites exposed
•
•
Calcium ions in sarcoplasm bind to troponin
Troponin changes position and pulls tropomyosin molecule
away from myosin binding sites on actin
3. Cross-bridges form
•
Myosin heads bind to exposed active sites, forming crossbridges
4. Myosin heads pivot
•
•
Stored energy released and used to pivot myosin head
toward M line (power stroke)
Bound ADP and phosphate released
© 2013 Pearson Education, Inc.
Contraction Cycle (6.5)
5. Cross-bridges detach
•
A new ATP binds to myosin head causing release of myosin head
from actin
•
Active site available to form another cross-bridge
6. Myosin reactivated
•
Free myosin head splits ATP into ADP and
phosphate
•
•
Released energy used to recock myosin head
Cycle repeats as long as ATP and calcium are available
© 2013 Pearson Education, Inc.
Contraction Cycle End (6.5)
1. Stimulus from motor neuron stops
2. Acetylcholine broken down in synaptic cleft
3. Action potential along sarcolemma and T-tubules
ceases
4. Sarcoplasmic reticulum pumps calcium out of
sarcoplasm and stores for future
5. Troponin molecules shift back to original position
6. Tropomyosin covers active sites on actin
preventing cross-bridge formation
© 2013 Pearson Education, Inc.
Muscle fiber contraction cycle
Active-Sites Exposed
Resting Sarcomere
Contraction Cycle Begins
Cross-Bridges Form
Sarcoplasm
Myosin head
Troponin
Active
site
Actin
Tropomyosin
Cross-Bridges Detach
Contracted Sarcomere
© 2013 Pearson Education, Inc.
Myosin Heads Pivot
Myosin Reactivated
Figure 6.5 1
Module 6.5 Review
a. What molecule supplies energy for a muscle
contraction?
b. List the five interrelated steps that occur once the
contraction cycle has begun.
c. What triggers myosin reactivation?
© 2013 Pearson Education, Inc.
Review of Events (Section 2)
1. Skeletal muscle stimulated to contract by motor neuron
2. Action potential in motor neuron causes release of ACh
into synaptic cleft
3. Binding of ACh to receptors opens sodium channels,
causing action potential along sarcolemma (excitation)
and T-tubules
4. Action potential in T-tubules triggers release of calcium
from sarcoplasmic reticulum
5. Calcium allows interaction between thin and thick
filaments, shortening sarcomere and muscle fibers
6. Entire skeletal muscle shortens, producing tension on
tendons
© 2013 Pearson Education, Inc.
Sequence of events in muscle contraction
Neural Control
Action potential along
motor neuron
Excitation–contraction coupling
Action potential causes release of ACh,
which binds to receptors and opens sodium
channels, producing an action potential in
sarcolemma.
Excitation
Action potential along sarcolemma
and T tubules triggers calcium
release from sarcoplasmic reticulum.
Calcium
release
triggers
Contraction cycle begins.
Thick–thin
filaments interact
Muscle fiber
contraction
leads to
Tension
production
© 2013 Pearson Education, Inc.
Figure 6 Section 2 1
Muscle Twitch (6.6)
• Single stimulus-contraction-relaxation sequence in
muscle fiber
• Twitches vary in duration depending on:
• Muscle type and location
• Internal and external environmental conditions
© 2013 Pearson Education, Inc.
Myogram showing muscle twitch in different muscles
Tension
Eye muscle Deep muscle
of the calf
0
10
20
30
40
50 60 70
Time (msec)
80
90
100
Stimulus
© 2013 Pearson Education, Inc.
Figure 6.6 11
Phases of a Muscle Twitch (6.6)
• Latent period
• From stimulation to about 2 msec; no tension developed
• Action potential moving along sarcolemma, calcium released from
sarcoplasmic reticulum
• Contraction phase
• From beginning of tension development to peak tension (about 13
msec)
• Calcium binding to troponin, cross-bridge cycling occurring
• Relaxation phase
• From peak tension to end of twitch (about 25 msec)
• Calcium levels fall, cross-bridges detach, tension returns to resting
level
© 2013 Pearson Education, Inc.
Myogram of muscle twitch in gastrocnemius muscle
Tension
Maximum tension
development
Contraction
phase
Resting
phase Stimulus
Time (msec)0
5
10
Latent period Contraction phase
© 2013 Pearson Education, Inc.
Relaxation
phase
20
30
Relaxation phase
40
Figure 6.6 12
Wave Summation (6.6)
• With second stimulus before end of relaxation
period:
• More powerful contraction produced
• Addition of one twitch to another called wave summation
© 2013 Pearson Education, Inc.
Tension
Wave summation
KEY
= Stimulus
Time
Wave summation
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Figure 6.6 13
Incomplete Tetanus (6.6)
• Rapid cycle of contraction and relaxation produces
almost peak tension
• Still shows period of relaxation, so called
incomplete tetanus
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Incomplete tetanus
Tension
Maximum tension (in tetanus)
KEY
= Stimulus
Time
Incomplete tetanus
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Figure 6.6 14
Complete Tetanus (6.6)
• Higher stimulation frequency eliminates relaxation
phase
• No calcium ions taken back into sarcoplasmic
reticulum
• Results in continuous contraction called complete
tetanus
© 2013 Pearson Education, Inc.
Tension
Complete tetanus
KEY
= Stimulus
Time
Complete tetanus
© 2013 Pearson Education, Inc.
Figure 6.6 15
Module 6.6 Review
a. Define a twitch.
b. Describe the events occurring during the
relaxation phase of a twitch.
c. Contrast complete and incomplete tetanus.
© 2013 Pearson Education, Inc.
Muscle Fibers and Motor Units (6.7)
• Skeletal muscle composed of thousands of muscle
fibers
• Motor unit is single motor neuron and all muscle
fibers it innervates
• Size of motor unit indicates precision of movement
• Smaller motor units for more precision
• Motor fibers of different motor units intermingled
• Recruitment
• Smaller units activated first, followed by larger, more
powerful motor units, increasing tension
© 2013 Pearson Education, Inc.
Skeletal muscle tension is controlled by the number of motor units stimulated
Spinal cord
Cell bodies of
motor neurons
Axons
of motor
neurons
Muscle fibers of each motor
unit are intermingled with
those of other motor units.
© 2013 Pearson Education, Inc.
Motor nerve (collection
of motor neuron axons)
KEY
Motor unit 1
Motor unit 2
Motor unit 3
Figure 6.7 11
Muscle Tone (6.7)
• Some motor units active even when muscle is not
contracting
• Activation tenses and firms muscle
• Resting tension called muscle tone
• Subconscious process changes which motor units
active, maintaining constant tension, yet letting
individual fibers relax
© 2013 Pearson Education, Inc.
Module 6.7 Review
a. Define motor unit.
b. What is recruitment?
c. Describe the relationship between the number of
fibers in a motor unit and the precision of body
movements.
© 2013 Pearson Education, Inc.
Isotonic Contraction (6.8)
• Contraction in which tension rises and skeletal
muscle length changes
• Tension rises until it exceeds load
• Then as muscle shortens, tension remains
constant (isotonic)
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Isotonic contraction
Tendon
Muscle
contracts
(isotonic
contraction)
Amount
of load
4
Muscle
tension 2
(kg)
0
Peak tension
production
2 kg
2 kg
© 2013 Pearson Education, Inc.
Contraction
begins
Muscle
relaxes
Figure 6.8 1 -12 – 2
Isometric Contraction (6.8)
• Muscle length stays the same (isometric)
• Individual muscle fibers shorten
• Connective tissue stretches
• Tension does not exceed load
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Isometric contraction
6
4
Muscle
tension 2
(kg) 0
Muscle
contracts
(isometric
contraction)
Amount of load
Peak tension
production
Contraction
begins
6 kg
© 2013 Pearson Education, Inc.
6 kg
Figure 6.8 33- 4– 4
Module 6.8 Review
a. Compare an isotonic contraction and an
isometric contraction.
b. Can a skeletal muscle contract without
shortening? Why or why not?
c. In the two graphs above, which contraction
produced the greater tension?
© 2013 Pearson Education, Inc.
Sources of ATP in Skeletal Muscle Fibers (6.9)
• At rest, mitochondria produce surplus ATP from
fatty acids and glucose
• ATP used to form creatine phosphate (from creatine) and
glycogen (from glucose)
• With moderate activity, increased demand for ATP
• ATP production by aerobic (with oxygen) metabolism of
pyruvate in mitochondria
• 6-carbon glucose broken down by enzymes into two 3carbon pyruvate molecules
• No fatigue until glycogen, lipid, and amino acid reserves
exhausted
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ATP production at rest
Fatty acids
G
Blood vessels
Glycogen
Glucose
Mitochondria
Creatine
Muscle at rest
© 2013 Pearson Education, Inc.
Figure 6.9 11
ATP production during moderate activity
Fatty acids
Glucose
Glycogen
2
2
Pyruvate
34
34
To myofibrils to support
muscle contraction
Muscle at moderate activity levels
© 2013 Pearson Education, Inc.
Figure 6.9 12
Peak Activity ATP Production (6.9)
• Mitochondria ATP production at maximum rate
• Only 1/3 of needed ATP produced by aerobic means
• Remaining 2/3 of required ATP produced
anaerobically (without oxygen)
• Glucose to pyruvate
• Pyruvate converted to lactic acid
• Lactic acid dissociates into lactate and hydrogen ion,
lowering pH
• Lowered pH changes enzymes, preventing muscle fiber
from contracting, resulting in muscle fatigue
© 2013 Pearson Education, Inc.
ATP production during peak activity
Lactate
Glucose
Glycogen
2
2
Pyruvate
Creatine
Lactate
To myofibrils to support
muscle contraction
Muscle at peak activity levels
© 2013 Pearson Education, Inc.
Figure 6.9 13
Recovery (6.9)
• Cori cycle
• Lactate produced in muscle during peak activity diffuses into
bloodstream
• Liver converts lactate to pyruvate
• 30 percent of pyruvate broken down in mitochondria
for energy
• Remaining 70 percent converted back into glucose
• Glucose released into bloodstream to rebuild glycogen
reserves in muscle
• Amount of oxygen required to restore normal
conditions is oxygen debt
© 2013 Pearson Education, Inc.
Cori cycle
Peak Activity
Recovery
20–30%
Pyruvate
LIVER
70–80%
Glucose
Lactate
Lactate
MUSCLE
Pyruvate
Glucose
Glucose
Glycogen reserves in muscle
© 2013 Pearson Education, Inc.
Figure 6.9 44
Module 6.9 Review
a. Identify the two compounds in which energy is
stored in resting muscle fibers.
b. Under what conditions do muscle fibers produce
lactate?
c. Define oxygen debt.
© 2013 Pearson Education, Inc.
Muscle Hypertrophy (6.10)
• Repeated, exhaustive stimulation causes muscle fibers to
develop
• More mitochondria
• More glycolytic enzymes
• Larger glycogen reserves
• More myofibrils
• Enlargement of whole muscle (hypertrophy)
• Increased muscle strength
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Muscle hypertrophy
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Figure 6.10 11
Muscle Atrophy (6.10)
• Lack of stimulation to skeletal muscle causes:
• Loss of muscle mass and tone
• Decreased size of muscle fibers (atrophy)
• Loss of muscle strength
• Atrophy
• Somewhat natural process of aging
• May be temporary with injury or cast immobilization
• Dying muscle fibers not replaced, so can be permanent
© 2013 Pearson Education, Inc.
Muscle atrophy
© 2013 Pearson Education, Inc.
Figure 6.10 22
Clinical Conditions Affecting Skeletal Muscles
(6.10)
• Polio
• Virus attacks motor neurons in spinal cord and brain
• Causes muscular atrophy and paralysis
• Tetanus
• Caused by bacterium Clostridium tetani that lives in lowoxygen environments (deep puncture wounds)
• Releases toxin suppressing motor neuron inhibition, resulting
in sustained, powerful contractions
• 40–60 percent mortality rate
© 2013 Pearson Education, Inc.
Clinical Conditions Affecting Skeletal Muscles
(6.10)
• Botulism
• Caused by bacterium Clostridium botulinum
• Releases toxin that prevents ACh release at neuromuscular
junction
• Result is paralysis of skeletal muscle
• Myasthenia gravis
• Disease characterized by loss of ACh receptors at
neuromuscular junction
• Result is progressive muscular weakness
© 2013 Pearson Education, Inc.
Conditions that indirectly affect the muscular system
The polio virus attacks motor
neurons in spinal cord and brain.
Tetanus toxin causes sustained,
powerful contraction of skeletal muscle
throughout the body.
Botulism prevents ACh release at the
neuromuscular junction. Myasthenia gravis
results in loss of ACh receptors at the
neuromuscular junction.
Without ATP, cross-bridges cannot detach, so the affected
muscle fibers lock in the contracted state.
© 2013 Pearson Education, Inc.
Figure 6.10 33
Skeletal Muscles without ATP (6.10)
• ATP production requires nutrients and oxygen
• Lack of either, caused by injury or death, results
in:
• No ATP
• Calcium cannot be pumped back into sarcoplasmic reticulum
• Cross-bridges cannot detach from active sites
• Sustained contraction
• This condition after death called rigor mortis
• SR deteriorates releasing calcium into sarcoplasm
• No ATP available
• Begins 2–7 hours after death, lasts until 1–6 days after
© 2013 Pearson Education, Inc.
Module 6.10 Review
a. Define muscle hypertrophy and muscle atrophy.
b. Six weeks after Fred broke his leg, the cast is
removed, and as he steps down from the exam
table, his leg gives way and he falls. Propose a
logical explanation.
c. Explain how the flexibility or rigidity of a dead
body can provide a clue to a murder victim's time
of death.
© 2013 Pearson Education, Inc.
Functional Organization of the Muscular
System (Section 3)
• Skeletal muscles are almost half of the weight of
body
• More than any other organ system
• Organized into:
• Axial muscles
• Support and position axial skeleton
• Appendicular muscles
• Support, move, and brace limbs
© 2013 Pearson Education, Inc.
Skeletal muscles account for almost half of body weight
Lymphatic system 0.3%
Reproductive system 0.15%
Endocrine system 0.15%
Cardiovascular system 9%
Urinary system 0.7%
Respiratory system 1.7%
Nervous system 2%
Digestive system 6%
Integumentary
system
16%
Axial
muscles
Skeletal
system
20%
Muscular system
44%
Tendons conduct the
forces of contraction to
perform specific tasks.
© 2013 Pearson Education, Inc.
Appendicular
muscles
Figure 6 Section 3
Skeletal Muscle Functional Terms (6.11)
• Origin
• Where fixed end of skeletal muscle attaches
• Insertion
• Where movable end of skeletal muscle attaches
• Action
• Specific movement of a skeletal muscle
© 2013 Pearson Education, Inc.
Origin and insertion of skeletal muscles
Origins of biceps
brachii muscle
Action
Insertion of biceps
brachii muscle
© 2013 Pearson Education, Inc.
Figure 6.11 11
Functional Description of Muscles (6.11)
• Agonist or prime mover
• Responsible for producing particular movement
• Example: biceps brachii in bending elbow
• Synergist
• Helps agonist work efficiently by providing additional pull or
stability
• Example: brachioradialis in bending elbow
• Antagonist
• Opposes action of agonist
• Example: triceps brachii in bending elbow
© 2013 Pearson Education, Inc.
Muscles may be described by their functions
Agonist, or prime mover,
in bending the elbow
Antagonist in
bending the elbow
Synergist helps the agonist
and stabilizes the elbow joint
Insertion of
brachioradialis
muscle
© 2013 Pearson Education, Inc.
Origin of
brachioradialis
muscle
Figure 6.11 22
Naming Muscles (6.11)
• Skeletal muscles named according to:
• Region of body (femoris = thigh)
• Position (posterior = back)
• Nature of origin (biceps = two heads)
• Shape (deltoid = triangle)
• Size (maximus = largest)
• Action (flexor = bending movement)
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
Figure 6.11 33
Module 6.11 Review
a. Define the term synergist as it relates to muscle
actions.
b. What is the relationship between the biceps
brachii and the triceps brachii?
c. What does the name flexor carpi radialis longus
tell you about this muscle?
© 2013 Pearson Education, Inc.
Flexion and Extension (6.12)
• Applied to movement of long bones of limbs and to
movements of axial skeleton
• Flexion
• Movement that reduces angle between structures
• Extension
• Movement that increases angle between structures
• Hyperextension
• Extension beyond anatomical position
PLAY
Articulations: Elbow Flexion/Extension
© 2013 Pearson Education, Inc.
Flexion and extension in the body
Extension
Flexion
Hyperextension
Flexion
Extension
Hyperextension
© 2013 Pearson Education, Inc.
Figure 6.12 11
Specific Flexion Terms (6.12)
• Lateral flexion
• When vertebral column bends to side
• Dorsiflexion
• Flexion at ankle joint involving elevation of sole of
foot (toes pointing upwards)
• Plantar flexion
• Extension at ankle joint (toes pointing downward)
PLAY
Articulations: Foot Dorsiflexion/Plantar Flexion
© 2013 Pearson Education, Inc.
Lateral flexion of the head
Lateral flexion
© 2013 Pearson Education, Inc.
Figure 6.12 11
Dorsiflexion and plantar flexion
Dorsiflexion
(ankle flexion)
Plantar
flexion (ankle
extension)
© 2013 Pearson Education, Inc.
Figure 6.12 11
Abduction and Adduction (6.12)
• Refers to movement of appendicular skeleton
• Abduction
• Movement away from longitudinal axis
• Spreading fingers or toes (moving away from midline)
• Adduction
• Movement toward longitudinal axis
• Bringing fingers or toes together (moving toward midline)
PLAY
Articulations: Humerus Abduction/Adduction
© 2013 Pearson Education, Inc.
Abuction and adduction
Adduction
Abduction
Abduction
Adduction
Abduction
Adduction
Abduction
Adduction
Abduction
Adduction
© 2013 Pearson Education, Inc.
Figure 6.12 22
Circumduction (6.12)
• Tracing large circle with hand while keeping arm
straight
• Movement occurring at shoulder called
circumduction
PLAY
Articulations: Humerus Circumduction
© 2013 Pearson Education, Inc.
Circumduction
© 2013 Pearson Education, Inc.
Figure 6.12 33
Module 6.12 Review
a. When doing jumping jacks, which lower limb
movements are necessary?
b. Which movements are associated with hinge
joints?
c. Compare dorsiflexion to plantar flexion.
© 2013 Pearson Education, Inc.
Rotation (6.13)
• Rotation can be of trunk or limbs
• Trunk directional terms with reference to anatomical
position
• Left rotation (looking to left)
• Right rotation (looking to right)
• Limbs
• Medial rotation or internal or inward rotation
• Anterior surface of limb turned toward trunk
• Lateral rotation or external or outward rotation
• Opposite movement
© 2013 Pearson Education, Inc.
Rotational movements in the body
Right
rotation
Lateral
(external)
rotation
© 2013 Pearson Education, Inc.
Left
rotation
Medial
(internal)
rotation
Figure 6.13 11
Movement at Proximal Radio-Ulnar Joint (6.13)
• Rotation of radial head causing rolling of distal epiphysis of
radius across anterior surface of ulna
• Pronation
• Turning wrist and hand from palm facing front to palm
facing back
• Supination
• Turning wrist and hand from palm facing back to palm
facing front
PLAY
Articulations: Elbow Pronation/Supination
© 2013 Pearson Education, Inc.
Supination and pronation of the arm
© 2013 Pearson Education, Inc.
Supination
Pronation
Figure 6.13 11
Special Movements (6.13)
• Opposition
• Movement of thumb toward palm or pads of other
fingers
• Inversion and eversion involve twisting motion of
foot
• Inversion turning sole inward; eversion turning sole
outward
PLAY
Articulations: Hand Opposition
PLAY
Articulations: Foot Inversion/Eversion
© 2013 Pearson Education, Inc.
Special Movements (6.13)
• Protraction and retraction
• Protraction moving body part anteriorly in horizontal
plane
• Retraction moving body part posteriorly in horizontal
plane
• Depression and elevation
• Depression moving in inferior direction; elevation
moving in superior direction
© 2013 Pearson Education, Inc.
Special movements
Opposition
Eversion
Retraction Protraction
Inversion
Depression
© 2013 Pearson Education, Inc.
Elevation
Figure 6.13 22
Module 6.13 Review
a. Snapping your fingers involves what movement
with the thumb and third metacarpophalangeal
joint?
b. What movements are made possible by the
rotation of the radius head?
c. What hand movements occur when wriggling into
tight-fitting gloves?
© 2013 Pearson Education, Inc.
Axial and Appendicular Muscles (6.14)
• Axial muscles
• Make up about 60 percent of skeletal muscles
• Originate on axial skeleton
• Position head and spinal column
• Move rib cage and assist in breathing
• Appendicular muscles
• Stabilize or move parts of appendicular skeleton
• Make up 40 percent of skeletal muscles
© 2013 Pearson Education, Inc.
Axial division of skeletal muscles
Axial Muscles
Appendicular Muscles
Temporalis
Clavicle
Sternum
Frontalis
Sternocleidomastoid
Rectus abdominis
External oblique
Linea alba
Flexor retinaculum
Iliotibial tract
Patella
Tibia
Superior extensor retinaculum
Inferior extensor retinaculum
Trapezius
Deltoid
Pectoralis major
Latissimus dorsi
Serratus anterior
Biceps brachii
Triceps brachii
Brachialis
Pronator teres
Brachioradialis
Extensor carpi radialis
Palmaris longus
Flexor carpi radialis
Flexor digitorum superficialis
Flexor carpi ulnaris
Gluteus medius
Tensor fasciae latae
Iliopsoas
Pectineus
Adductor longus
Gracilis
Sartorius
Rectus femoris
Vastus lateralis
Vastus medialis
Gastrocnemius
Fibularis longus
Tibialis anterior
Soleus
Extensor digitorum longus
Lateral malleolus of fibula
Medial malleolus of tibia
© 2013 Pearson Education, Inc.
Figure 6.14 11
Appendicular division of skeletal muscles
Appendicular Muscles
Axial Muscles
Trapezius
Deltoid
Infraspinatus
Teres minor
Teres major
Rhomboid major
Triceps brachii (long head)
Triceps brachii (lateral head)
Latissimus dorsi
Brachioradialis
Extensor carpi radialis
Anconeus
Flexor carpi ulnaris
Extensor digitorum
Extensor carpi ulnaris
Gluteus medius
Tensor fasciae latae
Gluteus maximus
Adductor magnus
Semitendinosus
Semimembranosus
Gracilis
Biceps femoris
Sartorius
Plantaris
Gastrocnemius
Soleus
Occipitalis
Sternocleidomastoid
External oblique
Iliotibial tract
Calcaneal
tendon
Calcaneus
© 2013 Pearson Education, Inc.
Figure 6.14 22
Module 6.14 Review
a. What are the functions of the axial muscles?
b. Identify the division (axial or appendicular) to
which each of the following muscles belongs:
biceps brachii, external oblique, temporalis, and
vastus medialis.
c. Which structures labeled in the figures in this
module are not muscles?
© 2013 Pearson Education, Inc.
Muscles of the Head and Neck (6.15)
• Function in facial expression
• Muscles originate on surface of skull
• Insert into connective tissue and dermis of skin
• Function in eating by moving jaw
© 2013 Pearson Education, Inc.
Anterior view of muscles of the head and neck with origin, insertion, and action
Facial Muscles
Frontalis
Aponeurosis of scalp
Origin: Aponeurosis of scalp
Facial Muscles
Insertion: Skin of eyebrow and
bridge of nose
Temporalis
Action: Raises eyebrows,
wrinkles forehead
Origin: Along temporal lines of skull
Insertion: Coronoid process of
mandible
Orbicularis oculi
Action: Elevates mandible and
closes the jaws
Origin: Medial margin of orbit
Insertion: Skin around eyelids
Masseter
Action: Closes eye
Origin: Zygomatic arch
Zygomaticus
Insertion: Lateral surface of
mandibular ramus
Action: Elevates mandible and
closes the jaws
Origin: Zygomatic bone
Insertion: Angle of mouth and
upper lip
Buccinator
Action: Retracts and elevates corner
of mouth and upper lip
Origin: Alveolar process of
maxillary bone and mandible
Platysma
Insertion: Fibers of orbicularis oris
Action: Compresses cheeks
Origin: Superior thorax between
cartilage of 2nd rib and
acromion of scapula
Orbicularis oris
Insertion: Mandible and skin of cheek
Origin: Maxillary bones and
mandible
Action: Tenses skin of neck,
depresses mandible
Insertion: Lips
Action: Compresses, purses lips
Clavicle
© 2013 Pearson Education, Inc.
Figure 6.15 11
Lateral view of muscles of the head and neck with origin, insertion, and action
Occipitalis
Facial muscles
Origin: Occipital and
temporal bones
Frontalis
Insertion:Aponeurosis of scalp
Action: Tenses and retracts scalp
Temporalis
Orbicularis oculi
Zygomaticus
Buccinator
Orbicularis oris
Sternocleidomastoid
Masseter
Origin: One head from the
clavicle; the other head
from the manubrium
Insertion:Mastoid region of skull,
temporal bone and
adjacent portions of
occipital bone
Action: Flexes the neck; one
alone bends head
towards shoulder and
rotates the neck
© 2013 Pearson Education, Inc.
Figure 6.15 22
Module 6.15 Review
a. Where do the muscles of facial expression
originate?
b. You bite into an apple. Name the muscles
involved.
c. Which muscles do you contract to produce a
smile?
© 2013 Pearson Education, Inc.
Muscles of the Vertebral Column (6.16)
• Arranged in several layers
• Originate or insert on ribs and vertebral processes
• Group as a whole extends from sacrum to skull
• Numerous individual muscles of different lengths
© 2013 Pearson Education, Inc.
Muscles of the vertebral column with origin, insertion, and action
Spinal Extensors, Superficial Layer
Splenius capitis
Erector Spinae
Spinalis
Origin: Spinous and transverse processes of
thoracic and superior lumbar vertebrae
Insertion: Spinous processes of superior
thoracic vertebrae
Action: Extend vertebral column
Longissimus
Origin: Transverse processes of inferior
cervical, thoracic, and lumbar vertebrae
Insertion: Mastoid process of temporal bone;
transverse processes of middle and
superior cervical and thoracic
vertebrae; inferior surfaces of ribs
Action: Together, the two sides extend the
vertebral column; alone, each rotates
and laterally flexes it to that side
Iliocostalis
Origin: Superior borders of ribs, iliac crest,
sacral crests, and spinous processes
of lumbar vertebrae
Insertion: Transverse processes of middle and
inferior cervical vertebrae; inferior
surfaces of inferior seven ribs
Action: Extend or laterally flex vertebral
column, elevate or depress ribs
© 2013 Pearson Education, Inc.
Quadratus lumborum
Origin: Iliac crest
Insertion: Last rib and transverse
processes of lumbar
vertebrae
Action: Together, they depress
ribs; alone each side
laterally flexes vertebral
column
Thora
codorsal
fascia
Posterior view
Figure 6.16 11
Module 6.16 Review
a. Name the erector spinae muscles from medial to
lateral in relation to the vertebral column.
b. Which vertebral column muscles originate on the
iliac crest?
c. Name the spinal extensor muscles that have
insertions on the skull.
© 2013 Pearson Education, Inc.
Oblique and Rectus Muscles (6.17)
• Oblique muscles at an angle to body
• Rectus muscles parallel to body axis
© 2013 Pearson Education, Inc.
Oblique and rectus muscles of the trunk with origin, insertion, and action
Oblique Group
Thoracic Region
External intercostals
Origin: Inferior border of each rib
Pectoralis
major
Insertion: Superior border of more
inferior rib
Action: Elevate ribs
Internal intercostals
Origin: Superior border of each rib
Serratus
anterior
Insertion: Inferior border of the
adjacent superior rib
Rectus abdominis
Action: Depress ribs
Origin: Superior surface
of pubis near the
symphysis
Abdominal Region
External oblique
Insertion: Inferior surfaces of
costal cartilages
(ribs 5–7) and
xiphoid process
Origin: External and inferior
borders of ribs 5–12
Insertion: Linea alba and iliac crest
Action: Depress ribs, flex
vertebral column,
compress abdomen
Action: Compress abdomen;
depress ribs, flex or bend
vertebral column
Internal oblique
Linea alba
Origin: Lumbodorsal fascia and
iliac crest
Insertion: Inferior ribs, xiphoid
process, and linea alba
Action: Compress abdomen;
depress ribs, flex or bend
vertebral column
Cut edge of rectus sheath
Anterior view
Transversus abdominis
© 2013 Pearson Education, Inc.
Origin: Cartilages of ribs 6–12,
iliac crest, and
lumbodorsal fascia
Insertion: Linea alba and pubis
Action: Compress abdomen
Figure 6.17 11
Module 6.17 Review
a. Name the abdominal muscles from superficial to
deep.
b. Damage to the external intercostal muscles
would interfere with what important process?
c. If someone hit you in the rectus abdominis
muscle, how would your body position change?
© 2013 Pearson Education, Inc.
Muscles Originating on the Trunk (6.18)
• Control gross movements of limbs
• Often large and powerful
• Posterior trunk muscles
• Mostly appendicular that originate on large bones of
limb girdles (pelvic, pectoral) and proximal bones of
limbs
© 2013 Pearson Education, Inc.
Anterior view of axial and appendicular muscles of the trunk with origin, insertion, and action
Superficial Dissection
Deep Dissection
Axial Muscles
Axial Muscles
Platysma
Sternocleidomastoid
Appendicular Muscles
Appendicular Muscles
Deltoid
Trapezius
Origin: Clavicle and scapula
Insertion: Deltoid tuberosity of
humerus
Action: Abduction, flexion,
extension, medial
and lateral rotation
at the shoulder
Pectoralis major
Deltoid (cut and reflected)
Pectoralis major (cut and reflected)
Pectoralis minor
Origin: Ribs 3–5
Insertion:
Coracoid process
of scapula
Action:
Depress and
protract shoulder;
rotate scapula,
elevate ribs
Origin: Rib cartilages 2–6,
sternum, and clavicle
Insertion: Crest of tubercle and
lateral lip of intertubercular groove of
humerus
Action: Flexion, adduction,
and medial rotation
at the shoulder
Latissimus dorsi
Serratus anterior
Axial Muscles
Coracobrachialis
Serratus anterior
Origin: Margins of ribs 1–8
(or 9)
Insertion: Anterior surface of
vertebral border of
scapula
Action:
Protract shoulder;
rotate scapula
Axial Muscles
External oblique
External intercostal
Rectus abdominis
Internal intercostal
Internal oblique (cut)
Transversus abdominis
© 2013 Pearson Education, Inc.
Figure 6.18 11
Posterior view of appendicular muscles of the trunk with origin, insertion, and action
Superficial Dissection
Nuchal ligament
Deep Dissection
Appendicular Muscles
Trapezius
Origin: Occipital bone, nuchal
ligament, and spinous
processes of thoracic
Vertebrae
Insertion: Clavicle and scapula
Action: Elevate or rotate scapula,
elevate clavicle, or extend
neck
Deltoid
Latissimus dorsi
Origin: Spinous processes of
lumbar and inferior
thoracic vetebrae, ribs
8–12, and lumbodorsal
fascia
Insertion: Floor of intertubercular
groove of the humerus
Action: Extension, adduction, and
medial rotation at shoulder
Gluteus medius
Origin: Iliac crest, gluteal lines of
ilium
Insertion: Greater trochanter of
femur
Action: Abduction and medial
rotation at hip
Gluteus maximus
Origin: Iliac crest, ilium, sacrum,
coccyx, and lumbodorsal
fascia
Insertion: Iliotibial tract and gluteal
tuberosity of femur
Appendicular Muscles
Levator scapulae
Origin: Transverse processes
of first 4 cervical
vertebrae
Insertion: Vertebral border of
scapula near superior
angle
Action: Elevate scapula
Rhomboid muscles
Origin: Spinous processes
of C7–T5 vertebrae
Insertion:Vertebral border of
scapula
Action: Adduct scapula
Axial Muscles
Erector spinae muscle group
External oblique
Iliac crest
Thoracolumbar fascia
Action: Extension and lateral
rotation at hip
© 2013 Pearson Education, Inc.
Figure 6.18 22
Module 6.18 Review
a. You shrug your shoulders. Which muscles are
involved?
b. List the appendicular muscles that insert on the
humerus. Which raises the arm?
c. Identify to which division, axial or appendicular,
the following muscles belong: deltoid, external
oblique, gluteus maximus, pectoralis major.
© 2013 Pearson Education, Inc.
Upper Limb Muscles (6.19)
• Proximal muscles larger, stronger, fewer, and less precise
than distal muscles
• Muscles involved in extension of elbow and wrist located
on posterior surface
• Muscles involved in flexion of elbow and wrist located on
anterior surface
• Flexor and extensor retinacula hold tendons of muscles
in place
© 2013 Pearson Education, Inc.
Posterior view of muscles involved in extension of elbow and wrist with origin, insertion, and action
Head of humerus
Infraglenoid tubercle of scapula
Elbow Extensors
Wrist Extensors
Triceps brachii
Origin: One head from the
superior, lateral
margin of
humerus, one from
the posterior
surface of the
humerus, and one
from the scapula
Insertion: Olecranon of ulna
Action: Extension of elbow,
plus extension and
adduction at the
shoulder
Muscles that Extend
the Fingers
Extensor digitorum muscles
Origin: Lateral epicondyle
of the humerus
Insertion: Posterior surfaces
of the phalanges
Action: Extension at finger
joints and wrist
© 2013 Pearson Education, Inc.
Extensor carpi radialis
Origin: Lateral epicondyle
of humerus
Insertion: Base of second
and third
metacarpal bones
Action: Extension and
abduction of wrist
Olecranon
of ulna
Flexor carpi
ulnaris
Radius
Extensor carpi ulnaris
Origin: Lateral epicondyle
of humerus;
adjacent dorsal
surface of ulna
Insertion: Base of fifth
metacarpal bone
Action: Extension and
adduction of wrist
Ulna
Extensor retinaculum
Several muscles
originating at the
forearm and wrist
control complex
movements of the
thumb.
Figure 6.19 11
Anterior view of muscles involved in flexion at the elbow and wrist with origin, insertion, and action
Coracoid process
of scapula
Elbow Flexors
Biceps brachii
Origin: One head from the coracoid process of
the scapula; the other from a tubercle
bove the glenoid cavity
Insertion: Tuberosity of radius
Action: Flexion at elbow and
shoulder; supination
Brachialis
Origin: Anterior, distal surface of humerus
Insertion: Tuberosity of ulna
Action: Flexion at elbow
Brachioradialis
Origin: Ridge superior to the lateral
epicondyle of humerus
Insertion: Lateral aspect of styloid
process of radius
Action: Flexion at elbow
Muscles that Flex the Fingers
Flexor digitorum muscles
Origin: Medial epicondyle of
humerus; surface of ulna
Insertion: Anterior surfaces of phalanges
Action: Flexion of finger joints
Humerus
Elbow Extensors
Triceps brachii
Medial epicondyle of humerus
Wrist Flexors
Flexor carpi radialis
Origin: Medial epicondyle of
humerus
Insertion: Base of second and
third metacarpal
bones
Action: Flexion and abduction
of wrist
Flexor carpi ulnaris
Origin: Medial epicondyle of
humerus; olecranon
of ulna
Insertion: Medial carpals and
fifth metacarpal bone
Action: Flexion and
adduction of wrist
Flexor retinaculum
© 2013 Pearson Education, Inc.
Figure 6.19 22
Module 6.19 Review
a. Name the limb muscle that inserts on the
olecranon of the ulna and give its action.
b. Which muscles are involved in flexion at the
elbow?
c. Injury to the flexor carpi ulnaris muscle would
impair which two movements?
© 2013 Pearson Education, Inc.
Posterior Upper Leg Muscles (6.20)
• Flexors of knee originate on pelvic girdle and are
found on posterior and medial surface of thigh
• Hamstring muscles include:
• Semitendinosus
• Biceps femoris
• Semimembranosus
© 2013 Pearson Education, Inc.
Anterior view of muscles involved in flexion at the elbow and wrist with origin, insertion, and action
Iliac crest
Gluteus medius
Tensor fasciae latae
Gluteus maximus
Flexors of the Knee
Semitendinosus (hamstring muscle)
Origin: Ischial tuberosity
Insertion: Proximal, medial
surface of tibia
Action: Flexion at knee;
extension and medial
rotation at hip
Adductor Group
Adductor muscles
Origin: Inferior ramus of pubis
Insertion: Linea aspera of femur
Action: Adduction and
flexion at hip
Biceps femoris (hamstring muscle)
Origin: Ischial tuberosity and
linea aspera of femur
Insertion: Head of fibula, lateral
condyle of tibia
Action: Flexion at knee; extension
and lateral rotation at hip
Gracilis
Origin: Inferior ramus of pubis
Insertion:Medial surface of tibia
inferior to the medial
condyle
Action: Flexion at knee;
adduction and medial
rotation at hip
Semimembranosus (hamstring muscle)
Iliotibial
tract
Origin: Ischial tuberosity
Insertion: Posterior surface of medial
condyle of tibia
Action: Flexion at knee;
extension and medial
rotation at hip
Sartorius
Origin: Anterior superior
iliac spine
Insertion:Medial surface of tibia
Action: Flexion at knee; flexion
and lateral rotation at hip
© 2013 Pearson Education, Inc.
Figure 6.20 11
Anterior Upper Leg Muscles (6.20)
• Extensors of knee originate on femoral surface and are
found on anterior and lateral surfaces of thigh
• Quadriceps muscles include:
• Rectus femoris
• Vastus lateralis
• Vastus intermedius
• Vastus medialis
© 2013 Pearson Education, Inc.
Posterior view of hip and thigh muscles with origin, insertion, and action
Anterior superior iliac spine
Tensor fasciae latae
Origin: Iliac crest and anterior superior
iliac spine
Insertion: Iliotibial tract
Action: Flexion and medial rotation of
hip
Iliopsoas muscles
Origin: Iliac fossa of ilium, and
vertebrae T12–L5
Insertion: Lesser trochanter of femur
Action: Flexion at hip
Pubic tubercle
Extensors of the Knee
(Quadriceps muscles)
Adductor muscles
Rectus femoris
Origin: Anterior inferior iliac spine
and rim of acetabulum
Insertion: Tibial tuberosity via patellar
ligament
Sartorius
Action: Extension at knee; flexion
at hip
Vastus lateralis
Origin: Greater trochanter of femur,
linea aspera
Insertion: Tibial tuberosity via patellar
ligament
Extension
at knee
Action:
Vastus intermedius (lies deep to
rectus femoris and vastus lateralis)
Origin: Surface of femur and linea
aspera
Insertion: Tibial tuberosity via patellar
ligament
Action: Extension at knee
Vastus medialis
Origin: Entire length of linea aspera of
femur
Insertion: Tibial tuberosity via patellar
ligament
Action: Extension at knee
Quadriceps tendon
Patella
Patellar ligament
Tibial tuberosity
© 2013 Pearson Education, Inc.
Figure 6.20 22
Module 6.20 Review
a. Name the quadriceps muscles.
b. Which muscles flex the knee?
c. Predict which action and muscles you would use
to sit down on a chair.
© 2013 Pearson Education, Inc.
Lower Leg Muscles (6.21)
• Ankle extensors (produce plantar flexion of foot)
• Gastrocnemius
• Soleus
• Muscles moving toes are smaller and originate on
tibia, fibula, or both
• Superior and inferior retinacula hold tendons of
muscles in place where they cross ankle joint
© 2013 Pearson Education, Inc.
Posterior views of muscles that move the foot and toes with origin, insertion, and action
Deep Dissection
Superficial Dissection
Ankle Extensor
Gastrocnemius
Origin: Femoral condyles
Insertion: Calcaneus via calcaneal
tendon
Action: Extension (plantarflexion) at
the ankle
Head of
fibula
Soleus
Origin: Head and shaft of fibula, and
posteromedial shaft of tibia
Insertion: Calcaneus via calcaneal
tendon
Action: Extension (plantar flexion) at
the ankle
Fibularis longus
Origin: Lateral condyle of tibia, head
and proximal fibula
Insertion: First metacarpal bone and
medial cuneiform bone
Action: Eversion of foot and extension
at the ankle; supports the arch
of the foot
Digital Flexors
Flexor digitorum longus
Origin: Posterior and medial surfaces
of tibia
Calcaneal
tendon
Calcaneus
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Calcaneal
tendon
(cut)
Insertion: Inferior surfaces of distal
phalanges
Action: Flexion at joints of toes 2–5
Figure 6.21 11
Lateral and medial views of muscles that move the foot and toes with origin, insertion, and action
Lateral View
Medial View
Ankle Flexors
Iliotibial tract
Tibialis anterior
Origin: Lateral condyle
and proximal shaft
of tibia
Head of fibula
Ankle Extensors
Gastrocnemius
Fibularis longus
Soleus
Insertion: Base of first
metatarsal bone
and medial
cuneiform bone
Action: Flexion
(dorsiflexion) at
ankle; inversion of
foot
Patellar ligament
Medial surface
of tibial shaft
Ankle Extensors
Gastrocnemius
Soleus
Digital Extensors
Extensor digitorum longus
Origin: Lateral condyle of
tibia, anterior fibula
Superior extensor
retinaculum
Calcaneal tendon
Insertion: Phalanges of
toes 2–5
Action: Extension at joints
of toes 2–5
Superior extensor
retinaculum
Calcaneal tendon
Inferior extensor
retinaculum
Inferior extensor
retinaculum
Tendon of
tibialis anterior
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Figure 6.21 12
Module 6.21 Review
a. Name the muscles that produce plantar flexion.
b. You let up on the gas pedal while driving. Identify
the action and muscles involved.
c. How would a torn calcaneal tendon affect
movement of the foot?
© 2013 Pearson Education, Inc.