Title: Neuromuscular Fundamentals
1Neuromuscular Fundamentals
- Anatomy and Physiology of Human Movement
- 420050
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
- Protection
- Posture and support
- Produce a major portion of total body heat
- 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 - muscles work in groups
rather than independently to achieve a given
joint motion
4Muscle Tissue Properties
- Irritability or Excitability - property of muscle
being sensitive or responsive to chemical,
electrical, or mechanical stimuli - Contractility - ability of muscle to contract
develop tension or internal force against
resistance when stimulated - Extensibility - ability of muscle to be passively
stretched beyond it normal resting length - Elasticity - ability of muscle to return to its
original length following stretching
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 Receptor sites
- Cell body Integration
- Axon Transmission
- Myelin sheath Protection and speed
- Nodes of Ranvier Saltatory conduction
- Terminal branches Increased innervation
- Axon terminals Connection with muscular system
- Synaptic vescicles Delivery mechanism of
message - Neurotransmitter The message
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
17Skeletal Muscle Properties
- Extensibility The ability to lengthen
- Contractility The ability to shorten
- Elasticity The ability to return to original
length - Irritability The ability to receive and respond
to stimulus
18Muscular 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
19Figure 10.1, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
20Figure 10.4, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
21http//staff.fcps.net/cverdecc/Adv20AP/Notes/Mus
cle20Unit/sliding20filament20theory/slidin16.jp
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22Figure 10.8, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
23Structure and Function
- Nervous system structure
- Muscular system structure
- Neuromuscular function
24Neuromuscular 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
25Nerve 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
26Nerve 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
27Nerve 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.
28Nerve 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.
29Nerve Impulse
- What is repolarization?
- -Return of the RMP to 70 mV
Figure 12.9, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
3030 mV
-70 mV
31Neuromuscular 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
32Release of the Neurotransmitter
- Action potential ? axon terminals
- 1. Calcium uptake
- 2. Release of synaptic vescicles (ACh)
- 3. Vescicles release ACh
- 4. ACh binds sarcolemma
33Figure 12.8, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
Ca2
ACh
34Figure 14.5, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
35Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
36Ach
37AP Along the Sarcolemma
- Action potential ? Transverse tubules
- 1. T-tubules carry AP inside
- 2. AP activates sarcoplasmic reticulum
38Figure 14.5, Marieb Mallett (2003). Human
Anatomy. Benjamin Cummings.
39Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding Filaments
40Calcium Release
- AP ? T-tubules ? Sarcoplasmic reticulum
- 1. Activation of SR
- 2. Calcium released into sarcoplasm
41CALCIUM RELEASE
Sarcolemma
42Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
43Coupling of Actin and Myosin
44Blocked
Coupling of actin and myosin
45Neuromuscular Function
- 1. Nerve impulse
- 2. Neurotransmitter release
- 3. Action potential along sarcolemma
- 4. Calcium release
- 5. Coupling of actin and myosin
- 6. Sliding filaments
46Sliding Filament Theory
- Basic Progression of Events
- 1. Cross-bridge
- 2. Power stroke
- 3. Dissociation
- 4. Reactivation of myosin
47Cross-Bridge
- Activation of myosin via ATP
- -ATP ? ADP Pi Energy
- -Activation ? cocked position
48Power Stroke
- ADP Pi are released
- Configurational change
- Actin and myosin slide
49Dissociation
- New ATP binds to myosin
- Dissociation occurs
50Reactivation 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
51(No Transcript)
52Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
53Shape of Muscles Fiber Arrangement
- Muscles have different shapes fiber
arrangements - Shape fiber arrangement affects
- Muscles ability to exert force
- Range through which it can effectively exert
force onto the bones
54Shape of Muscles Fiber Arrangement
- Two major types of fiber arrangements
- Parallel pennate
- Each is further subdivided according to shape
55Fiber Arrangement - Parallel
- Parallel muscles
- fibers arranged parallel to length of muscle
- produce a greater range of movement than similar
sized muscles with pennate arrangement - Categorized into following shapes
- Flat
- Fusiform
- Strap
- Radiate
- Sphincter or circular
56Fiber Arrangement - Parallel
- Flat muscles
- Usually thin broad, originating from broad,
fibrous, sheet-like aponeuroses - Allows them to spread their forces over a broad
area - Ex Rectus abdominus external oblique
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
57Fiber Arrangement - Parallel
- Fusiform muscles
- Spindle-shaped with a central belly that tapers
to tendons on each end - Allows them to focus their power onto small, bony
targets - Ex Brachialis, biceps brachii
Figure 3.3. Hamilton, Weimar Luttgens (2005).
Kinesiology Scientific basis for human motion.
McGraw-Hill.
58Fiber Arrangement - Parallel
- Strap muscles
- More uniform in diameter with essentially all
fibers arranged in a long parallel manner - Enables a focusing of power onto small, bony
targets - Ex Sartorius, sternocleidomastoid
Figure 8.7. Hamilton, Weimar Luttgens (2005).
Kinesiology Scientific basis for human motion.
McGraw-Hill.
59Fiber Arrangement - Parallel
- Radiate muscles
- Also described sometimes as being triangular,
fan-shaped or convergent - Have combined arrangement of flat fusiform
- Originate on broad aponeuroses converge onto a
tendon - Ex Pectoralis major, trapezius
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
60Fiber Arrangement - Parallel
- Sphincter or circular muscles
- Technically endless strap muscles
- Surround openings function to close them upon
contraction - Ex Orbicularis oris surrounding the mouth
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
61Fiber Arrangement - Pennate
- Pennate muscles
- Have shorter fibers
- Arranged obliquely to their tendons in a manner
similar to a feather - Reduces mechanical efficiency of each fiber
- Increases overall number of fibers packed into
muscle - Overall effect more crossbridges more force!
62Fiber Arrangement - Pennate
- Categorized based upon the exact arrangement
between fibers tendon - Unipennate
- Bipennate
- Multipennate
Modified from Van De Graaff KM Human anatomy, ed
6, Dubuque, IA, 2002, McGraw-Hill.
63Fiber Arrangement - Pennate
- Unipennate muscles
- Fibers run obliquely from a tendon on one side
only - Ex Biceps femoris, extensor digitorum longus,
tibialis posterior
64Fiber Arrangement - Pennate
- Bipennate muscle
- Fibers run obliquely on both sides from a central
tendon - Ex Rectus femoris, flexor hallucis longus
65Fiber Arrangement - Pennate
- Multipennate muscles
- Have several tendons with fibers running
diagonally between them - Ex Deltoid
- Bipennate unipennate produce more force than
multipennate
66Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
67Muscle Actions Terminology
- Origin (Proximal Attachment)
- Structurally, the proximal attachment of a muscle
or the part that attaches closest to the midline
or center of the body - Functionally historically, the least movable
part or attachment of the muscle - Note The least movable may not necessarily be
the proximal attachment
68Muscle Actions Terminology
- Insertion (Distal Attachment)
- Structurally, the distal attachment or the part
that attaches farthest from the midline or center
of the body - Functionally historically, the most movable
part is generally considered the insertion
69Muscle Actions Terminology
- When a particular muscle is activated
- It tends to pull both ends toward the center
- Actual movement is towards more stable attachment
- Examples
- Bicep curl vs. chin-up
- Hip extension vs. RDL
70Muscle Actions
- Action - when tension is developed in a muscle as
a result of a stimulus - Muscle contraction term is exclusive in nature
- As a result, it has become increasingly common to
refer to the various types of muscle contractions
as muscle actions instead
71Muscle Actions
- Muscle actions can be used to cause, control, or
prevent joint movement or - To initiate or accelerate movement of a body
segment - To slow down or decelerate movement of a body
segment - To prevent movement of a body segment by external
forces
72Types of Muscle Actions
- Muscle action (under tension)
- Isometric
- Isotonic
- Concentric
- Eccentric
73Types of Muscle Actions
- Isometric action
- Tension is developed within muscle but joint
angles remain constant - AKA Static movement
- May be used to prevent a body segment from being
moved by external forces - Internal torque external torque
74Types of Muscle Actions
- Isotonic (same tension) contractions involve
muscle developing tension to either cause or
control joint movement - AKA Dynamic movement
- Isotonic contractions are either concentric
(shortening) or eccentric (lengthening)
75Types of Muscle Actions
- Concentric contractions involve muscle developing
tension as it shortens - Internal torque gt external torque
- Causes movement against gravity or other
resistance - Described as being a positive action
- Eccentric contractions involve the muscle
lengthening under tension - External torque gt internal torque
- Controls movement caused by gravity or other
resistance - Described as being a negative action
76What 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
77Types of Muscle Actions
- Movement may occur at any given joint without any
muscle contraction whatsoever - referred to as passive
- solely due to external forces such as those
applied by another person, object, or resistance
or the force of gravity in the presence of muscle
relaxation
78Outline
- Introduction
- Structure and Function
- Fiber Arrangement
- Muscle Actions
- Role of Muscles
- Neural Control
- Factors that Affect Muscle Tension
79Role of Muscles
- Agonist muscles
- The activated muscle group during concentric or
eccentric phases of movement - Known as primary or prime movers, or muscles most
involved
80Role of Muscles
- Antagonist muscles
- Located on opposite side of joint from agonist
- Have the opposite concentric action
- Also known as contralateral muscles
- Work in cooperation with agonist muscles by
relaxing allowing movement - Reciprocal Inhibition
81(No Transcript)
82Role of Muscles
- Stabilizers
- Surround joint or body part
- Contract to fixate or stabilize the area to
enable another limb or body segment to exert
force move - Also known as fixators
83Role of Muscles
- Synergist
- Assist in action of agonists
- Not necessarily prime movers for the action
- Also known as guiding muscles
- Assist in refined movement rule out undesired
motions
84Role of Muscles
- Neutralizers
- Counteract or neutralize the action of another
muscle to prevent undesirable movements such as
inappropriate muscle substitutions - Activation to resist specific actions of other
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
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
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 - Activating those motor units containing a greater
number of muscle fibers (Number Coding) - Activating more motor units (Number Coding)
- Increasing the frequency of motor unit activation
(Rate Coding)
88Number Coding Rate Coding
- Number of muscle fibers per motor unit varies
significantly - From less than 10 in muscles requiring precise
and detailed such as muscles of the eye - To as many as a few thousand in large muscles
that perform less complex activities such as the
quadriceps and gastrocnemius
89Number Coding Rate Coding
- Greater contraction forces may also be achieved
by increasing the frequency or motor unit
activation (Rate Coding)
90All or None Principle
- Motor unit
- Single motor neuron all muscle fibers it
innervates - Typical muscle contraction
- The number of motor units responding (and number
of muscle fibers contracting) within the muscle
may vary significantly from relatively few to
virtually all - All of the fibers within the motor unit will fire
when stimulated by the CNS - All or None Principle - regardless of number,
individual muscle fibers within a given motor
unit will either fire contract maximally or not
at all
91Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
92Length - 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
93Figure 20.2, Plowman and Smith (2002). Exercise
Physiology, Benjamin Cummings.
94Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
95Force Velocity Relationship
- When muscle is contracting (concentrically or
eccentrically) the rate of length change is
significantly related to the amount of force
potential
96Force Velocity Relationship
- Maximum concentric velocity minimum resistance
- As load increases, concentric velocity decreases
- Eventually velocity 0 (isometric action)
97Force Velocity Relationship
- As load increases beyond muscles ability to
maintain an isometric contraction, the muscle
begins eccentric action - As load increases, eccentric velocity increases
- Eventually velocity maximum when muscle tension
fails
98Muscle Force Velocity Relationship
- Indirect relationship between force (load) and
concentric velocity - Direct relationship between force (load) and
eccentric velocity
99Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
100Uni Vs. Biarticular Muscles
- Uniarticular muscles
- Cross act directly only on the single joint
that they cross - Ex Brachialis
- Can only pull humerus ulna closer together
- Ex Gluteus Maximus
- Can only pull posterior femur and pelvis closer
together
101Uni Vs. Biarticular Muscles
- Biarticular muscles
- Cross act on two different joints
- May contract cause motion at either one or both
of its joints - Advantages over uniarticular muscles
102Advantage 1
- Can cause and/or control motion at more than one
joint - Rectus femoris Knee extension, hip flexion
- Hamstrings Knee flexion, hip extension
103Advantage 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
104Advantage 3
- Prevention of Reciprocal Inhibition
- This effect is negated with biarticular muscles
when they move concurrently - Concurrent movement
- Concurrent lengthening and shortening of
muscle - Countercurrent movement
- Both ends lengthen or shorten
105What if the muscles of the hip/knee were
uniarticular?
Hip
Knee
Ankle
Muscles stretched/shortened to extreme lengths!
Implication?
106Figure 20.2, Plowman and Smith (2002). Exercise
Physiology, Benjamin Cummings.
107Quasi-isometric action? Implication?
Hip
Knee
Ankle
108Active Passive Insufficiency
- Countercurrent muscle actions can reduce the
effectiveness of the muscle - As muscle shortens its ability to exert force
diminishes - Active insufficiency Diminished crossbridges
- As muscle lengthens its ability to move through
ROM or generate tension diminishes - Passively insufficiency Diminished crossbridges
and excessive passive tension
109Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
110Cross-Sectional Area
- Hypertrophy vs. hyperplasia
- Increased of myofilaments
- Increased size and of myofibrils
- Increased size of muscle fibers
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111Factors That Affect Muscle Tension
- Number Coding and Rate Coding
- Length-Tension Relationship
- Force-Velocity Relationship
- Uniarticular vs. Biarticular Muscles
- Cross-sectional Diameter
- Muscle Fiber Type
112Muscle Fiber Characteristics
- Three basic types
- 1. Type I
- -Slow twitch, oxidative, red
- 2. Type IIb
- -Fast twitch, glycolytic, white
- 3. Type IIa
- -FOG