1. © 2016 Pearson Education, Inc.

2. I. Overview of Muscle Tissue
A. Terminology
1. Terminologies: Myo, mys, and sarco are prefixes for muscle
2. Ex. sarcoplasm: muscle cell cytoplasm
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3. B. Three types of Muscle Tissue 1. Skeletal
a. Packaged into skeletal muscles
i. Organs that are attached to bones and skin
b. Skeletal muscle fibers
i. Another name for cells
ii. have striations (stripes)
c. Also called voluntary muscle
i. can be consciously controlled
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4. i. Makes up bulk of heart walls
2. Cardiac
a. Found only in heart
i. Makes up bulk of heart walls
b. Striated
c. Involuntary
i. cannot be controlled consciously
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5. 3. Smooth muscle a. Found in walls of hollow organs
i. Ex: stomach, bladder, & airways
b. Not striated
c. Involuntary
i. can contract on its own without nervous system stimulation
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6. Table 9.3-1 Comparison of Skeletal, Cardiac, and Smooth Muscle
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7. C. Characteristics of Muscle Tissue 1. Excitability (responsiveness)
a. ability to receive & respond to stimuli
2. Contractility
a. ability to shorten forcibly when stimulated
3. Extensibility
a. ability to be stretched
4. Elasticity
a. ability to recoil to resting length
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8. D. Muscle Functions 1. Produce movement
a. responsible for all locomotion and manipulation
b. Ex. walking, digesting food, pumping blood
2. Maintain posture and body position
3. Stabilize joints
4. Generate heat as they contract
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9. II. Skeletal Muscle Anatomy (Gross)
A. Nerve and Blood Supply
1. Each muscle has a nerve, artery, & veins
a. Consciously controlled skeletal muscle has nerves supplying every fiber to control activity
b. Contracting muscle fibers require huge amounts of oxygen and nutrients
c. Also need waste products removed quickly
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10. B. Connective Tissue Sheaths 1
B. Connective Tissue Sheaths 1. Each skeletal muscle, as well as each muscle fiber, is covered in connective tissue a. Support cells and reinforce whole muscle
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11. 2. Sheaths from external to internal:
a. Epimysium
i. dense irregular connective tissue
ii. surrounds entire muscle
b. Perimysium:
i. fibrous connective tissue
ii. surrounds fascicles
groups of muscle fibers
c. Endomysium
i. fine areolar connective tissue
ii. surrounds each muscle fiber
Remember: fibers = cells
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12. Perimysium wrapping a fascicle
Figure 9.1 Connective tissue sheaths of skeletal muscle: epimysium, perimysium, and endomysium.
Epimysium
Epimysium
Bone
Perimysium
Tendon
Endomysium
Muscle fiber
in middle of
a fascicle
Blood vessel
Perimysium wrapping a fascicle
Endomysium
(between individual muscle fibers)
Muscle fiber
Fascicle
Perimysium
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13. © 2016 Pearson Education, Inc.

14. 1. Muscles attach to bone in at least two places
C. Attachments
1. Muscles attach to bone in at least two places
a. Insertion
i. attachment to movable bone
b. Origin
i. attachment to immovable or less movable bone
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15. 2. Attachments can be direct or indirect a. Direct (fleshy) i
2. Attachments can be direct or indirect a. Direct (fleshy) i. epimysium fused to directly to bone or cartilage b. Indirect i. CT Sheaths extend beyond muscle as a ropelike tendon OR a sheetlike aponeurosis
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16. Epimysium Bone Tendon Blood vessel Perimysium wrapping a fascicle
Figure 9.1a Connective tissue sheaths of skeletal muscle: epimysium, perimysium, and endomysium.
Epimysium
Bone
Tendon
Blood vessel
Perimysium wrapping
a fascicle
Endomysium
(between individual
muscle fibers)
Muscle
fiber
Fascicle
Perimysium
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17. Table 9.1-1 Structure and Organizational Levels of Skeletal Muscle
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18. Bell Ringer
5.01 What are the 3 types of muscle tissue? 5.02 What is a group of muscle fibers called? 5.03 What is the difference between an origin and insertion?
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19. III. Muscle Fiber Microanatomy and Sliding Filament Model
A. Skeletal muscle fibers
1. Sarcolemma
a. muscle fiber plasma membrane
2. Sarcoplasm
a. muscle fiber cytoplasm
3. Modified organelles
a. Myofibrils
b. Sarcoplasmic reticulum
c. T tubules
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20. 1. Densely packed, rodlike elements
B. Myofibrils
1. Densely packed, rodlike elements
a. Single muscle fiber can contain 1000s
b. Myofibril features
i. Striations
ii. Sarcomeres
iii. Myofilaments
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21. Epimysium Bone Tendon Blood vessel Perimysium wrapping a fascicle
Figure 9.1a Connective tissue sheaths of skeletal muscle: epimysium, perimysium, and endomysium.
Epimysium
Bone
Tendon
Blood vessel
Perimysium wrapping
a fascicle
Endomysium
(between individual
muscle fibers)
Muscle
fiber
Fascicle
Perimysium
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22. Figure 9.2b Microscopic anatomy of a skeletal muscle fiber.
Diagram of part of a
muscle fiber showing
the myofibrils. One
myofibril extends from
the cut end of the fiber.
Sarcolemma
Mitochondrion
Myofibril
Dark A band
Light I band
Nucleus
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23. 2. Striations: stripes formed from series of
2. Striations: stripes formed from series of dark and light bands along length of each myofibril
a. A bands: dark regions
i. H zone: lighter region in middle of dark A band
ii. M line: line of protein that bisects H zone vertically
b. I bands: lighter regions
i. Z disc (line): sheet of proteins on midline of I band
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24. Figure 9.2b Microscopic anatomy of a skeletal muscle fiber.
Diagram of part of a
muscle fiber showing
the myofibrils. One
myofibril extends from
the cut end of the fiber.
Sarcolemma
Mitochondrion
Myofibril
Dark A band
Light I band
Nucleus
© 2016 Pearson Education, Inc.

25. Figure 9.2c Microscopic anatomy of a skeletal muscle fiber.
Thin (actin)
filament
Z disc
H zone
Z disc
Small part of one
myofibril enlarged to
show the myofilaments
responsible for the
banding pattern. Each
sarcomere extends from
one Z disc to the next.
Thick (myosin)
filament
I band
A band
I band
M line
Sarcomere
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26. Figure 9.2a Microscopic anatomy of a skeletal muscle fiber.
Photomicrograph of portions
of two isolated muscle
fibers (700×). Notice the
obvious striations (alternating
dark and light bands).
Nuclei
Dark A band
Light I band
Fiber
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27. a. Smallest contractile unit of muscle fiber
3. Sarcomere
a. Smallest contractile unit of muscle fiber
b. Consists of area between Z discs
i. Contains A band with half of an I band at each end
c. Individual sarcomeres align end to end along myofibril
i. like boxcars of train
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28. Figure 9.2c Microscopic anatomy of a skeletal muscle fiber.
Thin (actin)
filament
Z disc
H zone
Z disc
Small part of one
myofibril enlarged to
show the myofilaments
responsible for the
banding pattern. Each
sarcomere extends from
one Z disc to the next.
Thick (myosin)
filament
I band
A band
I band
M line
Sarcomere
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29. 4. Myofilaments (Proteins)
a. Actin myofilaments: thin filaments
i. Extend across I band and partway in A band
ii. Anchored to Z discs
b. Myosin myofilaments: thick filaments
i. Extend length of A band
ii. Connected at M line
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30. Figure 9.2c Microscopic anatomy of a skeletal muscle fiber.
Thin (actin)
filament
Z disc
H zone
Z disc
Small part of one
myofibril enlarged to
show the myofilaments
responsible for the
banding pattern. Each
sarcomere extends from
one Z disc to the next.
Thick (myosin)
filament
I band
A band
I band
M line
Sarcomere
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31. Bell Ringer
5.04 What connective tissue sheath covers each muscle fiber? 5.05 Which myofilament is also called the “thin filament”?
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32. C. Sarcoplasmic Reticulum and T Tubules 1
C. Sarcoplasmic Reticulum and T Tubules 1. Sarcoplasmic reticulum (SR) a. Smooth endoplasmic reticulum tubules surrounding each myofibril b. Stores and releases Ca2+
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33. 2. T tubules
a. Tube formed by protrusion of sarcolemma deep into cell interior
i. Increase muscle fiber’s surface area
b. Allow electrical nerve transmissions to reach deep into interior of each muscle fiber
i. When an electrical impulse passes by, SR releases calcium into cytoplasm
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34. Part of a skeletal muscle fiber (cell) I band A band I band Z disc
Figure 9.5 Relationship of the sarcoplasmic reticulum and T tubules to myofibrils of skeletal muscle.
Part of a skeletal
muscle fiber (cell)
I band
A band
I band
Z disc
H zone
Z disc M
line
Sarcolemma
Myofibril
Triad:
• T tubule
• Terminal
cisterns
of the SR (2)
Sarcolemma
Tubules of
the SR
Myofibrils
Mitochondria
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35. D. Sliding Filament Model of Contraction
1. Sliding filament model of contraction states that during contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more
a. In the relaxed state, thin and thick filaments overlap slightly at ends of A band
b. Neither thick nor thin filaments change length, just overlap more
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36. Figure 9.6-1 Sliding filament model of contraction.
Fully relaxed sarcomere of a muscle fiber Z H Z l A l
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37. 2. When nervous system stimulates muscle fiber, myosin heads are allowed to bind to actin
a. forms cross bridges, which cause sliding (contraction) process to begin
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38. 3. Cross bridge attachments form and break several times
a. each time pulling thin filaments a little closer toward center of sarcomere
b. Causes shortening of muscle fiber
i. Z discs are pulled toward M line
ii. I bands shorten
iii. Z discs become closer
iv. H zones disappear
v. A bands move closer to each other
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39. Figure 9.6-1 Sliding filament model of contraction.
Fully relaxed sarcomere of a muscle fiber Z H Z l A l
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40. Figure 9.6-2 Sliding filament model of contraction.
Fully contracted sarcomere of a muscle fiber Z Z l A l
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41. IV. Whole Muscle Contraction
Same principles apply to contraction of both single fibers and whole muscles
Contraction produces muscle tension
The force exerted on load or object to be moved
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42. 2. Contraction may/may not shorten muscle Isometric Contraction
No shortening
muscle tension increases but does not exceed load
Isotonic Contraction
Muscle shortens
Muscle tension exceeds load
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43. Figure 9.15b-1 Isotonic (concentric) and isometric contractions.
Muscle is attached to a weight that exceeds the
muscle’s peak tension-developing capabilities.
When stimulated, the tension increases to the
muscle’s peak tension-developing capability, but
the muscle does not shorten.
Muscle
contracts
(isometric
contraction)
6 kg
6 kg
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44. Figure 9.15a-1 Isotonic (concentric) and isometric contractions.
Isotonic contraction (concentric)
On stimulation, muscle develops enough tension
(force) to lift the load (weight). Once the resistance
is overcome, the muscle shortens, and the tension
remains constant for the rest of the contraction.
Tendon
Muscle
contracts
(isotonic
contraction)
3 kg
Tendon
3 kg
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45. 3. Force and duration of contraction vary in response to stimuli of different frequencies and intensities a. Each muscle is served by at least one motor nerve i. Motor Nerve contains axons of up to hundreds of motor neurons ii. Motor Unit is the nerve-muscle functional unit
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46. B. Motor unit
1. consists of the motor neuron and all muscle fibers (four to several hundred) it supplies
a. Smaller the fiber number, the greater the fine control
2. Muscle fibers from a motor unit are spread throughout the whole muscle
a. Stimulation of a single motor unit causes only weak contraction of entire muscle
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47. Branching axon terminals form neuromuscular junctions, one per muscle
Figure 9.10 A motor unit consists of one motor neuron and all the muscle fibers it innervates.
Spinal cord
Axon terminals at
neuromuscular
junctions
Branching axon
to motor unit
Motor
unit 1
Motor
unit 2
Nerve
Motor neuron
cell body
Motor neuron
axon
Muscle
Muscle
fibers
Branching axon terminals
form neuromuscular
junctions, one per muscle
fiber (photomicrograph 330×).
Axons of motor neurons extend from the spinal cord to the muscle. At the
muscle, each axon divides into a number of axon terminals that form neuromuscular
junctions with muscle fibers scattered throughout the muscle.
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48. C. Graded Muscle Responses
1. Normal muscle contraction is relatively smooth, and strength varies with needs
2. Graded muscle responses vary strength of contraction for different demands
a. Responses are graded by:
i. Changing frequency of stimulation
ii. Changing strength of stimulation
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49. 3. Muscle response to changes in stimulus frequency a
3. Muscle response to changes in stimulus frequency a. Single stimulus results in single contractile response (i.e., muscle twitch)
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50. Figure 9.12a A muscle’s response to changes in stimulation frequency.
Tension
Maximal tension of a single
twitch
Contraction
Relaxation
Stimulus
100
200
300
Time (ms)
Single stimulus: single twitch.
A single stimulus is delivered. The muscle contracts
and relaxes.
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51. b. Wave summation results of two or more stimuli are received by a muscle in rapid succession i. Muscle fibers do not have time to completely relax between stimuli ii. Twitches increase in force with each stimulus iii. Second stimulus causes more shortening
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52. Figure 9.12b A muscle’s response to changes in stimulation frequency.
Partial relaxation
Tension
Stimuli
100
200
300
Time (ms)
Low stimulation frequency: unfused (incomplete)
tetanus.
If another stimulus is applied before the muscle relaxes
completely, then more tension results. This is wave
(or temporal) summation and results in unfused (or
incomplete) tetanus.
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53. c. If stimuli frequncies increase, muscle tension reaches maximum i
c. If stimuli frequncies increase, muscle tension reaches maximum i. Referred to as fused (complete) tetanus ii. Contractions “fuse” into one smooth sustained contraction iii. Prolonged muscle contractions lead to muscle fatigue
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54. Figure 9.12c A muscle’s response to changes in stimulation frequency.
Tension
Stimuli
100
200
300
Time (ms)
High stimulation frequency: fused (complete)
tetanus.
At higher stimulus frequencies, there is no relaxation
at all between stimuli. This is fused (complete) tetanus.
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55. Bell Ringer
5.06 What is formed when a myosin head is allowed to bind to actin? 5.07 In what type of muscle contraction does the muscle NOT shorten?
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56. 4. Muscle response to changes in stimulus strength a
4. Muscle response to changes in stimulus strength a. Recruitment: Stimulus is sent to more muscle fibers i. leads to more precise control
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57. Proportion of motor units excited
Figure 9.13 Relationship between stimulus intensity (graph at top) and muscle tension (tracing below).
Stimulus strength
Maximal
stimulus
Stimulus voltage
Threshold
stimulus 1 2 3 4 5 6 7 8 9 10
Stimuli to nerve
Proportion of motor units excited
Strength of muscle contraction
Maximal contraction
Tension
Time (ms)
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58. b. Recruitment works on size principle
i. Motor units with smallest muscle fibers are recruited first
ii. Motor units with larger and larger fibers are recruited as stimulus intensity increases
iii. Largest motor units are activated only for most powerful contractions
iv. Some fibers contract while others rest
Helps prevent fatigue
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59. Figure 9.14 The size principle of recruitment.
Skeletal
muscle
fibers
Tension
Time
Motor
unit 1
recruited
(small
fibers)
Motor
unit 2
recruited
(medium
fibers)
Motor
unit 3
recruited
(large
fibers)
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60. D. Muscle Tone 1. Constant, slightly contracted state of all muscles a
D. Muscle Tone 1. Constant, slightly contracted state of all muscles a. Due to spinal reflexes 2. Keeps muscles firm, healthy and ready to respond
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61. V. Adaptation to Exercise
Aerobic (endurance) exercise
1. Examples: jogging, swimming, biking
2. leads to increased:
a. Muscle capillaries
b. Number of mitochondria
3. Results in greater endurance, strength, and resistance to fatigue
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62. B. Resistance exercise (typically anaerobic),
1. Examples: weight lifting or isometric exercises
2. leads to:
a. Muscle hypertrophy
i. Due primarily to increase in fiber size
b. Increased mitochondria, myofilaments, and connective tissue
3. Results in increased muscle strength and size
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63. Bell Ringer 5.08 What are the two main types of exercise?
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64. VI. Muscle Actions, Arrangements & Names
Muscle Actions and Interactions
1. Muscles can only pull; never push
a. What one muscle group “does,” another “undoes”
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65. a. Prime mover (agonist)
2. Functional groups
a. Prime mover (agonist)
i. Major responsibility for producing specific movement
b. Antagonist
i. Opposes or reverses particular movement
ii. Prime mover and antagonist are located on opposite sides of joint across which they act
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66. c. Synergist helps prime movers
i. Adds extra force to same movement
ii. Reduces undesirable or unnecessary movement
d. Fixator
i. Synergist that immobilizes bone or muscle’s origin
ii. Gives prime mover stable base on which to act
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67. 3. Same muscle may be: a. Prime mover of one movement b
3. Same muscle may be: a. Prime mover of one movement b. Antagonist for different movement c. Synergist for third movement
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68. B. Fascicle Arrangements 1
B. Fascicle Arrangements 1. All skeletal muscles consists of fascicles (bundles of fibers) a. vary, resulting in muscles with different shapes and functional capabilities
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69. 2. The most common patterns of arrangement a. Circular: i
2. The most common patterns of arrangement a. Circular: i. fascicles arranged in concentric rings b. Convergent: i. broad origin ii. fascicles converge toward single tendon insertion
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70. Figure 10.1a Patterns of fascicle arrangement in muscles.
Circular
(orbicularis oris)
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71. Figure 10.1b Patterns of fascicle arrangement in muscles.
Convergent
(pectoralis major)
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72. c. Parallel: i. fascicles parallel to long axis ii
c. Parallel: i. fascicles parallel to long axis ii. Forms straplike muscle d. Fusiform: i. spindle-shaped muscles with parallel fibers
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73. Figure 10.1d Patterns of fascicle arrangement in muscles.
Parallel
(sartorius)
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74. Figure 10.1c Patterns of fascicle arrangement in muscles.
Fusiform
(biceps brachii)
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75. fascicles attach only to one side of tendon Bipennate:
e. Pennate:
i. short fascicles attach obliquely to central tendon running length of muscle
ii. Three forms
Unipennate:
fascicles attach only to one side of tendon
Bipennate:
fascicles insert from opposite sides of tendon
Multipennate:
appears as feathers inserting into one tendon
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76. Figure 10.1g Patterns of fascicle arrangement in muscles.
Unipennate
(extensor digitorum
longus)
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77. Figure 10.1f Patterns of fascicle arrangement in muscles.
Bipennate
(rectus femoris)
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78. Figure 10.1e Patterns of fascicle arrangement in muscles.
Multipennate
(deltoid)
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79. Figure 10.1 Patterns of fascicle arrangement in muscles.
(b)
(c)
Circular
Convergent
(orbicularis oris)
(pectoralis major)
Multipennate
(deltoid)
(d)
(f)
Bipennate
(rectus femoris)
(g)
Fusiform
Parallel
Unipennate
(biceps brachii)
(sartorius)
(extensor digitorum
longus)
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80. Bell Ringer
5.09 What functional muscle group does the opposite of the prime mover? 5.10 What fascicle arrangement looks like multiple feathers?
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81. C. Naming Skeletal Muscles 1. Muscle location a
C. Naming Skeletal Muscles 1. Muscle location a. bone or body region with which muscle is associated b. Example: temporalis (over temporal bone) 2. Muscle Shape a. distinctive shapes b. Example: deltoid muscle i. deltoid = triangle
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82. 3. Muscle size a. maximus (largest) b. minimus (smallest) c
3. Muscle size a. maximus (largest) b. minimus (smallest) c. longus (long) 4. Direction of muscle fibers or fascicles a. rectus (fibers run straight up and down) b. transversus (fibers run at right angles) c. oblique (fibers run diagonally)
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83. 5. Number of origins a. biceps (two origins) b
5. Number of origins a. biceps (two origins) b. triceps (three origins) 6. Location of attachments a. named according to point of origin and insertion i. origin named first b. Example: sternocleidomastoid i. origin: sternum and clavicle ii. Insertion: mastoid process
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84. 7. Muscle action a. named for action they produce b
7. Muscle action a. named for action they produce b. Example: flexor or extensor
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