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Practical Anatomy and Physiology: The Skeletal Muscle System
ArticleinBiofeedback · June 2010
DOI: 10.5298/1081-5937-38.2.47
CITATIONS READS
5 6,547
3 authors, including:
Fredric Shaffer Randy Neblett
Truman State University Productive Rehabilitation Institute of Dallas for Ergonomics
61 PUBLICATIONS2,250 CITATIONS 84 PUBLICATIONS1,541 CITATIONS
SEE PROFILE SEE PROFILE
Some of the authors of this publication are also working on these related projects:
Central Sensitization View project
Biofeedback View project
All content following this page was uploaded by Randy Neblett on 27 February 2015.
The user has requested enhancement of the downloaded file.
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, Biofeedback E Association for Applied Psychophysiology & Biofeedback
Volume 38, Issue 2, pp. 47–51 www.aapb.org
SPECIAL ISSUE
Practical Anatomy and Physiology:
The Skeletal Muscle System
Fred Shaffer, PhD, BCB,1 and Randy Neblett, MA, LPC, BCB 2
1
Truman State University, Kirksville, MO;2PRIDE Research Foundation, Dallas, TX
Keywords: skeletal muscles, electromyography, SEMG biofeedback
This article is the first in a series that summarizes the by a plasma membrane called the sarcolemma. Each
essential anatomy and physiology of the body systems extrafusal muscle fiber is composed of hundreds to
that are trained in biofeedback and neurofeedback. This thousands of cylindrical myofibrils that are built from thin
article examines the skeletal muscle system, the types of and thick filaments. These filaments are shorter than a
skeletal muscle fibers, motor units, muscle action poten- muscle fiber and are stacked in compartments called
tials, the surface electromyographic signal, muscle con- sarcomeres that are separated by dense zones called Z
traction, sensory-motor integration, and practical recom- discs. Muscle fibers contract and generate force by pulling
mendations for beginning biofeedback professionals. Z discs together. This action shortens the sarcomeres and
produces movement at joints (see Figure 1).
Skeletal Muscle System Skeletal muscles are highly adaptable because they can
The word muscle is derived from the Latin mus, which generate a remarkable range of force. The same muscles
means ‘‘little mouse,’’ because the rippling that accompa- that can pick up a 1-ounce pencil can also lift a 14-pound
nies skeletal muscle contraction resembles mice scampering textbook (Marieb & Hoehn, 2007).
underneath the skin. Muscle tissue’s defining characteristic
is its conversion of chemical energy into mechanical energy Types of Skeletal Muscle Fibers
(Marieb & Hoehn, 2007). Muscles are the largest Skeletal muscle fibers vary in structure and function. Two
consumers of energy in the body. In an average individual, primary fiber categories are usually identified: slow-twitch,
muscles typically account for 70% to 85% of gross body or type I fibers, and fast-twitch, or type II fibers. Slow-twitch
weight. An individual’s muscles are housed in approxi- fibers are often referred to as red muscle. They are designed
mately 600 sacks of connective tissue called fascia. This for posture maintenance and sustained aerobic activity and
connective tissue provides boundaries of shape for muscles are generally resistant to fatigue. Fast-twitch fibers are often
and acts as glue to hold muscles in place (Marieb & Hoehn, referred to as white muscle. They are designed for quick
2007). Tendons are made of dense fascia that connect responses and heavy lifting, but they fatigue relatively
muscles to other structures, such as bones. Connective quickly. Nearly all skeletal muscles are composed of some
tissue contributes to the skeletal muscle system’s elasticity, proportion of both of these fibers based on the type of work
which allows muscle fibers to produce and transmit force that they are designed to perform (Saladin, 2007).
(Tortora & Derrickson, 2009).
Most skeletal muscles are attached to and move the Motor Units
Biofeedback | Summer 2010
bones of the skeleton. They appear striped (striated) due to Skeletal muscle fibers are organized into motor units that
alternating dark and light bands. They share many of the consist of an alpha motor neuron (nerve cell) in the spinal
structures found in other cells, but unlike other cells, they cord, the muscle fibers it controls, and an axon (nerve fiber)
contain more than one nucleus (Fox, 2009). that connects the two together. The end of the axon and the
The skeletal muscle system consists of extrafusal muscle muscle fiber are separated by a synapse (small space), called
fibers and connective tissue. Extrafusal fibers are enclosed the neuromuscular junction. When the neuron sends an
47
0 0
Practical Anatomy and Physiology: The Skeletal Muscle System
ArticleinBiofeedback · June 2010
DOI: 10.5298/1081-5937-38.2.47
CITATIONS READS
5 6,547
3 authors, including:
Fredric Shaffer Randy Neblett
Truman State University Productive Rehabilitation Institute of Dallas for Ergonomics
61 PUBLICATIONS2,250 CITATIONS 84 PUBLICATIONS1,541 CITATIONS
SEE PROFILE SEE PROFILE
Some of the authors of this publication are also working on these related projects:
Central Sensitization View project
Biofeedback View project
All content following this page was uploaded by Randy Neblett on 27 February 2015.
The user has requested enhancement of the downloaded file.
0 0
, Biofeedback E Association for Applied Psychophysiology & Biofeedback
Volume 38, Issue 2, pp. 47–51 www.aapb.org
SPECIAL ISSUE
Practical Anatomy and Physiology:
The Skeletal Muscle System
Fred Shaffer, PhD, BCB,1 and Randy Neblett, MA, LPC, BCB 2
1
Truman State University, Kirksville, MO;2PRIDE Research Foundation, Dallas, TX
Keywords: skeletal muscles, electromyography, SEMG biofeedback
This article is the first in a series that summarizes the by a plasma membrane called the sarcolemma. Each
essential anatomy and physiology of the body systems extrafusal muscle fiber is composed of hundreds to
that are trained in biofeedback and neurofeedback. This thousands of cylindrical myofibrils that are built from thin
article examines the skeletal muscle system, the types of and thick filaments. These filaments are shorter than a
skeletal muscle fibers, motor units, muscle action poten- muscle fiber and are stacked in compartments called
tials, the surface electromyographic signal, muscle con- sarcomeres that are separated by dense zones called Z
traction, sensory-motor integration, and practical recom- discs. Muscle fibers contract and generate force by pulling
mendations for beginning biofeedback professionals. Z discs together. This action shortens the sarcomeres and
produces movement at joints (see Figure 1).
Skeletal Muscle System Skeletal muscles are highly adaptable because they can
The word muscle is derived from the Latin mus, which generate a remarkable range of force. The same muscles
means ‘‘little mouse,’’ because the rippling that accompa- that can pick up a 1-ounce pencil can also lift a 14-pound
nies skeletal muscle contraction resembles mice scampering textbook (Marieb & Hoehn, 2007).
underneath the skin. Muscle tissue’s defining characteristic
is its conversion of chemical energy into mechanical energy Types of Skeletal Muscle Fibers
(Marieb & Hoehn, 2007). Muscles are the largest Skeletal muscle fibers vary in structure and function. Two
consumers of energy in the body. In an average individual, primary fiber categories are usually identified: slow-twitch,
muscles typically account for 70% to 85% of gross body or type I fibers, and fast-twitch, or type II fibers. Slow-twitch
weight. An individual’s muscles are housed in approxi- fibers are often referred to as red muscle. They are designed
mately 600 sacks of connective tissue called fascia. This for posture maintenance and sustained aerobic activity and
connective tissue provides boundaries of shape for muscles are generally resistant to fatigue. Fast-twitch fibers are often
and acts as glue to hold muscles in place (Marieb & Hoehn, referred to as white muscle. They are designed for quick
2007). Tendons are made of dense fascia that connect responses and heavy lifting, but they fatigue relatively
muscles to other structures, such as bones. Connective quickly. Nearly all skeletal muscles are composed of some
tissue contributes to the skeletal muscle system’s elasticity, proportion of both of these fibers based on the type of work
which allows muscle fibers to produce and transmit force that they are designed to perform (Saladin, 2007).
(Tortora & Derrickson, 2009).
Most skeletal muscles are attached to and move the Motor Units
Biofeedback | Summer 2010
bones of the skeleton. They appear striped (striated) due to Skeletal muscle fibers are organized into motor units that
alternating dark and light bands. They share many of the consist of an alpha motor neuron (nerve cell) in the spinal
structures found in other cells, but unlike other cells, they cord, the muscle fibers it controls, and an axon (nerve fiber)
contain more than one nucleus (Fox, 2009). that connects the two together. The end of the axon and the
The skeletal muscle system consists of extrafusal muscle muscle fiber are separated by a synapse (small space), called
fibers and connective tissue. Extrafusal fibers are enclosed the neuromuscular junction. When the neuron sends an
47
0 0
