Title: Neuromuscular Fundamentals
1Neuromuscular Fundamentals
- Anatomy and Kinesiology
- 420024
2Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
3Introduction
- Responsible for movement of body and all of its
joints - Muscles also provide
- Over 600 skeletal muscles comprise approximately
40 to 50 of body weight - 215 pairs of skeletal muscles usually work in
cooperation with each other to perform opposite
actions at the joints which they cross - Aggregate muscle action
4Muscle Tissue Properties
- Irritability or Excitability
- Contractility
- Extensibility
- Elasticity
5Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
6Structure and Function
- Nervous system structure
- Muscular system structure
- Neuromuscular function
7Figure 14.1, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
8Nervous System Structure
- Integration of information from millions of
sensory neurons ? action via motor neurons
Figure 12.1, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
9Nervous System Structure
- Organization
- Brain
- Spinal cord
- Nerves
- Fascicles
- Neurons
Figure 12.2, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
Figure 12.7, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
10Nervous System Structure
- Both sensory and motor neurons in nerves
Figure 12.11, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
11Nervous System Structure
- The neuron Functional unit of nervous tissue
(brain, spinal cord, nerves) - Dendrites
- Cell body
- Axon
- Myelin sheath
- Nodes of Ranvier
- Terminal branches
- Axon terminals
- Synaptic vescicles
- Neurotransmitter
12Dendrites
Cell body
Axon
Myelin sheath
Node of Ranvier
Terminal ending
Terminal branch
Figure 12.4, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
13Figure 12.8, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
Terminal ending
Synaptic vescicle
Neurotransmitter Acetylcholine (ACh)
14Figure 12.19, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
15Structure and Function
- Nervous system structure
- Muscular system structure
- Neuromuscular function
16Classification of Muscle Tissue
- Three types
- 1. Smooth muscle
- 2. Cardiac muscle
- 3. Skeletal muscle
17Muscular System Structure
- Organization
- Muscle (epimyseum)
- Fascicle (perimyseum)
- Muscle fiber (endomyseum)
- Myofibril
- Myofilament
- Actin and myosin
- Other Significant Structures
- Sarcolemma
- Transverse tubule
- Sarcoplasmic reticulum
- Tropomyosin
- Troponin
18Figure 10.1, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
19Figure 10.4, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
20http//staff.fcps.net/cverdecc/Adv20AP/Notes/Mus
cle20Unit/sliding20filament20theory/slidin16.jp
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21Figure 10.8, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
22Structure and Function
- Nervous system structure
- Muscular system structure
- Neuromuscular function
23Neuromuscular Function
- Basic Progression
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
24Nerve Impulse
- What is a nerve impulse?
- -Transmitted electrical charge
- -Excites or inhibits an action
- -An impulse that travels along an axon is an
ACTION POTENTIAL
25Nerve Impulse
- How does a neuron send an impulse?
- -Adequate stimulus from dendrite
- -Depolarization of the resting membrane
potential - -Repolarization of the resting membrane
potential - -Propagation
26Nerve Impulse
- What is the resting membrane potential?
- -Difference in charge between inside/outside of
the neuron
-70 mV
Figure 12.9, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
27Nerve Impulse
- What is depolarization?
- -Reversal of the RMP from 70 mV to 30mV
Propagation of the action potential
Figure 12.9, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
28Nerve Impulse
- What is repolarization?
- -Return of the RMP to 70 mV
Figure 12.9, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
2930 mV
-70 mV
30Neuromuscular Function
- Basic Progression
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
31Release of the Neurotransmitter
- Action potential ? axon terminals
- 1. Calcium uptake
- 2. Release of synaptic vescicles (ACh)
- 3. Vescicles release ACh
- 4. ACh binds sarcolemma
32Figure 12.8, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
Ca2
ACh
33Figure 14.5, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
34Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
35Ach
36AP Along the Sarcolemma
- Action potential ? Transverse tubules
- 1. T-tubules carry AP inside
- 2. AP activates sarcoplasmic reticulum
37Figure 14.5, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
38Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding Filaments
39Calcium Release
- AP ? T-tubules ? Sarcoplasmic reticulum
- 1. Activation of SR
- 2. Calcium released into sarcoplasm
40CALCIUM RELEASE
Sarcolemma
41Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
42Coupling of Actin and Myosin
43Blocked
Coupling of actin and myosin
44Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
45Sliding Filament Theory
- Basic Progression of Events
- 1. Cross-bridge
- 2. Power stroke
- 3. Dissociation
- 4. Reactivation of myosin
46Cross-Bridge
- Activation of myosin via ATP
- -ATP ? ADP Pi Energy
- -Activation ? cocked position
47Power Stroke
- ADP Pi are released
- Configurational change
- Actin and myosin slide
48Dissociation
- New ATP binds to myosin
- Dissociation occurs
49Reactivation of Myosin Head
- ATP ? ADP Pi Energy
- Reactivates the myosin head
- Process starts over
- Process continues until
- -Nerve impulse stops
- -AP stops
- -Calcium pumped back into SR
- -Tropomyosin/troponin back to original position
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51Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
52Shape of Muscles Fiber Arrangement
- Muscles have different shapes fiber
arrangements - Shape fiber arrangement affects
53Shape of Muscles Fiber Arrangement
- Two major types of fiber arrangements
54Fiber Arrangement - Parallel
- Parallel muscles
- Categorized into following shapes
- Flat
- Fusiform
- Strap
- Radiate
- Sphincter or circular
55Fiber Arrangement - Parallel
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
56Fiber Arrangement - Parallel
Figure 3.3. Hamilton, Weimar Luttgens (2005).
Kinesiology Scientific basis for human motion.
McGraw-Hill.
57Fiber Arrangement - Parallel
Figure 8.7. Hamilton, Weimar Luttgens (2005).
Kinesiology Scientific basis for human motion.
McGraw-Hill.
58Fiber Arrangement - Parallel
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
59Fiber Arrangement - Parallel
- Sphincter or circular muscles
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
60Fiber Arrangement - Pennate
61Fiber Arrangement - Pennate
- Categorized based upon the exact arrangement
between fibers tendon
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
62Fiber Arrangement - Pennate
63Fiber Arrangement - Pennate
64Fiber Arrangement - Pennate
- Multipennate muscles
- Bipennate unipennate produce more force than
multipennate
65Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
66Muscle Actions Terminology
- Origin (Proximal Attachment)
67Muscle Actions Terminology
- Insertion (Distal Attachment)
68Muscle Actions Terminology
- When a particular muscle is activated
- Examples
- Bicep curl vs. chin-up
- Hip extension vs. RDL
69Muscle Actions
70Muscle Actions
- Muscle actions can be used to cause, control, or
prevent joint movement or
71Types of Muscle Actions
MUSCLE ACTION (under tension)
72Types of Muscle Actions
73Types of Muscle Actions
- Isotonic (same tension)
- Isotonic contractions are either concentric
(shortening) or eccentric (lengthening)
74Types of Muscle Actions
- Concentric contractions involve muscle developing
tension as it shortens - Eccentric contractions involve the muscle
lengthening under tension
75What is the role of the elbow extensors in each
phase?
Modified from Shier D, Butler J, Lewis R Holes
human anatomy physiology, ed 9, Dubuque, IA,
2002, McGraw-Hill
76Types of Muscle Actions
77Types of Muscle Actions
- Movement may occur at any given joint without any
muscle contraction whatsoever
78Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
79Role of Muscles
80Role of Muscles
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82Role of Muscles
83Role of Muscles
84Role of Muscles
85Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
86Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Pennation
87Number Coding Rate Coding
- Difference between lifting a minimal vs. maximal
resistance is the number of muscle fibers
recruited (crossbridges) - The number of muscle fibers recruited may be
increased by
88Number Coding Rate Coding
- Number of muscle fibers per motor unit varies
significantly
89Number Coding Rate Coding
- As stimulus strength increases from threshold,
more motor units (Number Coding) are recruited
overall muscle contraction force increases in a
graded fashion
From Seeley RR, Stephens TD, Tate P Anatomy
physiology, ed 7, New York, 2006, McGraw-Hill.
90Number Coding Rate Coding
- Greater contraction forces may also be achieved
by increasing the frequency or motor unit
activation (Rate Coding) - Phases of a single muscle fiber contraction or
twitch - Stimulus
- Latent period
- Contraction phase
- Relaxation phase
91Number Coding Rate Coding
- Latent period
- Contraction phase
- Relaxation phase
From Powers SK, Howley ET Exercise physiology
theory and application to fitness and
performance, ed 4, New York, 2001 , McGraw-Hill.
92Number Coding Rate Coding
- Summation
- When successive stimuli are provided before
relaxation phase of first twitch has completed,
subsequent twitches combine with the first to
produce a sustained contraction - Generates a greater amount of tension than single
contraction would produce individually - As frequency of stimuli increase, the resultant
summation increases accordingly producing
increasingly greater total muscle tension
93Number Coding Rate Coding
From Powers SK, Howley ET Exercise physiology
theory and application to fitness and
performance, ed 4, New York, 2001 , McGraw-Hill.
94All or None Principle
- Motor unit
- Typical muscle contraction
- All or None Principle
95Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Pennation
96Length - Tension Relationship
- Maximal ability of a muscle to develop tension
exert force varies depending upon the length of
the muscle during contraction
Passive Tension
Active Tension
97Length - Tension Relationship
- Generally, depending upon muscle involved
98Length - Tension Relationship
- Generally, depending upon muscle involved
99Figure 20.2, Plowman and Smith (2002). Exercise
Physiology, Benjamin Cummings.
100Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Pennation
101Force Velocity Relationship
- When muscle is contracting (concentrically or
eccentrically) the rate of length change is
significantly related to the amount of force
potential
102Force Velocity Relationship
- Maximum concentric velocity minimum resistance
- As load increases, concentric velocity decreases
- Eventually velocity 0 (isometric action)
103Force Velocity Relationship
- As load increases beyond muscles ability to
maintain an isometric contraction - As load increases
- Eventually
104Muscle Force Velocity Relationship
- Indirect relationship between force (load) and
concentric velocity - Direct relationship between force (load) and
eccentric velocity
105Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Pennation
106Angle of Pull
- Angle between the line of pull of the muscle
the bone on which it inserts (angle toward the
joint) - With every degree of joint motion, the angle of
pull changes - Joint movements insertion angles involve mostly
small angles of pull
107Angle of Pull
- Angle of pull changes as joint moves through ROM
- Most muscles work at angles of pull less than 50
degrees - Amount of muscular force needed to cause joint
movement is affected by angle of pull Why?
108Angle of Pull
- Rotary component - Acts perpendicular to long
axis of bone (lever)
Modified from Hall SJ Basic biomechanics, New
York, 2003, McGraw-Hill.
109Angle of Pull
- If angle lt 90 degrees, the parallel component is
a stabilizing force - If angle gt 90 degrees, the force is a dislocating
force
What is the effect of gt/lt 90 deg on ability to
rotate the joint forcefully?
Modified from Hall SJ Basic biomechanics, New
York, 2003, McGraw-Hill.
110Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Pennation
111Uni Vs. Biarticular Muscles
- Uniarticular muscles
- Ex Brachialis
- Ex Gluteus Maximus
112Uni Vs. Biarticular Muscles
- Biarticular muscles
- May contract cause motion at either one or both
of its joints - Advantages over uniarticular muscles
113Advantage 1
- Can cause and/or control motion at more than one
joint
114Advantage 2
- Can maintain a relatively constant length due to
"shortening" at one joint and "lengthening" at
another joint (Quasi-isometric) - - Recall the Length-Tension Relationship
115Advantage 3
- Prevention of Reciprocal Inhibition
- This effect is negated with biarticular muscles
when they move concurrently - Concurrent movement
- Countercurrent movement
116What if the muscles of the hip/knee were
uniarticular?
Hip
Knee
Ankle
Muscles stretched/shortened to extreme lengths!
Implication?
117Figure 20.2, Plowman and Smith (2002). Exercise
Physiology, Benjamin Cummings.
118Quasi-isometric action? Implication?
Hip
Knee
Ankle
119Active Passive Insufficiency
- Countercurrent muscle actions can reduce the
effectiveness of the muscle - As muscle shortens its ability to exert force
diminishes - As muscle lengthens its ability to move through
ROM or generate tension diminishes
120Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Pennation
121Cross-Sectional Area
- Hypertrophy vs. hyperplasia
- Increased of myofilaments
- Increased size and of myofibrils
- Increased size of muscle fibers
http//estb.msn.com/i/6B/917B20A6BE353420124115B1A
511C7.jpg
122Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Reflexes
- Pennation
123Muscle Fiber Characteristics
- Three basic types
- 1. Type I
- -Slow twitch, oxidative, red
- 2. Type IIb
- -Fast twitch, glycolytic, white
- 3. Type IIa
- -FOG
124Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Angle of Pull
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
- Reflexes
- Pennation
125Effect of Fiber Arrangement on Force Output
- Concept 1 Force directly related to
cross-sectional area ? more fibers - Example Thick vs. thin longitudinal/fusiform
muscle? - Example Thick fusiform/longitudinal vs. thick
bipenniform muscle? - Concept 2 As degree of pennation increases, so
does of fibers per CSA
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