PowerPoint® to accompany
Medical Assisting
Chapter 26
Second Edition
Ramutkowski  Booth  Pugh  Thompson  Whicker
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
The Muscular System
Objectives
26-1 List the functions of muscle.
26-2 Explain how muscle tissue generates energy.
26-3 List the three types of muscle tissue and describe
the locations and characteristics of each.
26-4 Describe how smooth muscle produces peristalsis.
26-5 Describe the structure of a skeletal muscle.
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The Muscular System
Objectives (cont.)
26-7 List and define the various types of body
movements produced by skeletal muscles.
26-8 Define the terms origin and insertion.
26-9 List the major skeletal muscles of the body and
give the action of each.
26-10 Describe various disorders and diseases of the
muscular system.
3
Introduction
 Bones and joints do
not themselves
produce movement.
 The human body has
more than 600
individual muscles
 By alternating
between contraction
and relaxation,
muscles cause bones
and supported
structures to move.
You will focus on the differences among three muscle tissue
types, the structure of skeletal muscles, muscle actions, and
the names of skeletal muscles.
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Functions of Muscle
Muscle has the ability
to contract, and this
contraction allows
muscles to perform
various functions.
Functions:
 Movement
 Stability
 Control of body
openings and
passages
 Heat production
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Larger View
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Skeletal Muscle
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Functions of Muscle
 Movement:
 Skeletal muscles are attached to bones which
allow you to walk or wave your hand.
 Smooth muscle is found on organ walls such as
the intestine. Contractions produces movement
of food through the intestine.
 Cardiac muscle produces the pumping of the
blood in the heart.
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Functions of Muscle
 Stability:
 Muscles hold your bones together to
stabilize joints.
 Small muscles hold your vertebrae
together to stabilize your spinal column.
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Functions of Muscle
 Controlling of openings and passages:
 Muscles form valve like structures called
sphincters
 Sphincters control movement of substances in
and out of passages.
 A urethral sphincter prevents or allows
urination
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Functions of Muscle
 Heat production:
 When muscles contract heat is released
 This helps the body maintain a normal
temperature
 Moving your body can make you warmer if
you are cold.
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3 Types of Muscle Tissue
Muscle
Group
Major Location
Major Function
Mode of
Control
Skeletal
Muscle
Attached to bones
and skin of the
face
Produces body
movements and
facial expressions
Voluntary
Smooth
Muscle
Walls of hollow
organs, blood
vessels, and iris
Moves contents
through organs;
vasoconstriction
Involuntary
Cardiac
Muscle
Wall of the heart
Pumps blood
through heart
Involuntary
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Peristalsis




Rhythmic contraction that pushes substances
through tubes of the body.
Muscle fibers in visceral smooth muscle respond
to neurotransmitters but they also stimulate each
other to contract.
The muscle fibers tend to contract and relax
together.
This type of muscle produces an action called
peristalsis.
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Production of Energy
for Muscle
ATP (adenosine
triphosphate), a type of
chemical energy, is
needed for sustained or
repeated muscle
contractions.
Muscle cells must have
three ways to store or
make this substance:
 Creatine phosphate
 Aerobic respiration
of glucose
 Lactic acid production
13
Oxygen Debt
Oxygen debt develops when skeletal
muscles are used strenuously for a minute
or two and:
 supplies in the muscle are low
 the aerobic respiration of glucose can no
longer be used to produce ATP.
This process accounts for why you still burn
energy after you exercise.
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Muscle Fatigue
 Condition in which a muscle has lost its ability to
contract
 Develops due to an accumulation of lactic acid
 Occurs when the blood supply to a muscle is
interrupted
 A motor neuron loses its ability to release
acetylcholine onto muscle fibers
 Cramps or painful involuntary contractions of
muscles, can accompany muscle fatigue
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Apply Your Knowledge
What causes bones to move?
16
Apply Your Knowledge -Answer
What causes bones to move?
Bones move by alternating between contraction
and relaxation; muscles cause bones and
supported structures to move.
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Structure of Skeletal Muscles
 Skeletal muscles are the
major organs that make up
the muscular system
 Consists of connective
tissues, skeletal muscle
tissue, blood vessels, and
nerves
 When body movements are
produced, not just one
muscle is involved, but a
group of muscles contract
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Connective Tissue Coverings
 Fascia - covers entire skeletal muscles and separates them
from each other.
 Tendon - a tough, cord-like structure made of fibrous
connective tissue that connects muscles to bones.
 Aponeurosis - a tough, sheet-like structure made of fibrous
connective tissue that attaches muscles to other muscles.
 Epimysium - a thin covering that is just deep (underneath) to
the fascia of a muscle that surrounds the entire muscle.
 Perimysium - connective tissue divides a muscle into
sections called fascicles.
 Endomysium - covering of connective tissue surrounds
individual muscle cells.
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Attachments and Actions of
Skeletal Muscles
 Actions of skeletal
muscles depend largely
on what the skeletal
muscles are attached
 Insertion - an attachment
site that moves when a
muscle contracts.
 Origin - an attachment
site that does not move
when a muscle contracts
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Body Movements
Flexion – Bending a
body part
Extension –
Straightening a body
part
Hyperextension –
Extending a body part
past the normal
anatomical position
Dorsiflexion – Pointing
the toes up
Plantar flexion –
Pointing the toes down
Abduction – Moving a
body part away from
its position in the
anatomical position
Adduction – Moving a
body part toward its
position in the
anatomical position
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Body Movements (cont.)
CircumductionMoving a body part in
a circle; for example,
moving your arm in a
circular motion
Pronation – Turning the
palm of the hand
down
Supination – Turning
the palm of the hand
up
Inversion – Turning the
sole of the foot
medially
Eversion – Turning the
sole of the foot
laterally
Retraction – Moving a
body part posteriorly
Protraction – Moving a
body part anteriorly
22
Body Movements (cont.)
Elevation – Lifting a body part; for example, elevating
the shoulders as in a shrugging expression
Depression – Lowering a body part; for example,
lowering the shoulders
23
Apply Your Knowledge
The doctor has asked you to abduct the
patient’s leg, so he can see the patient’s
wound. In order to position the patient
correctly what will you have to do?
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Apply Your Knowledge - Answer
The doctor has asked you to abduct the
patient’s leg, so he can see the patients
wound. In order to position the patient
correctly what will you have to do?
Moving the patient’s leg away from its
position in the anatomical position.
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Major Skeletal Muscles
 The muscle name indicates the
location, size, action, shape, or
number of attachments of the muscle.
 As you study muscles, you will find it
easier to remember them if you think
about what the name describes.
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Muscles of the Head
 Sternocleidomastoid - pulls the head to one side
and also pulls the head to the chest
 Splenius capitis - rotates the head and allows it to
bend to the side
 Frontalis - raises the eyebrows
 Orbicularis oris - allows the lips to pucker
 Orbicularis oculi - allows the eyes to close
 Zygomaticus - pulls the corners of the mouth up
 Platysma - pulls the corners of the mouth down
 Masseter and temporalis - close the jaw
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Arm Muscles
 Pectoralis major - pulls the arm across the
chest; it also rotates and adducts the arms
 Latissimus dorsi - acts to extend, adduct,
and rotate the arm inwardly
 Deltoid - acts to abduct and extend the arm
at the shoulder
 Subscapularis - rotates the arm medially
 Infraspinatus - rotates the arm laterally
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Forearm Muscles
 Biceps brachii - flexes the arm at the elbow
and rotates the hand laterally
 Brachialis - flexes the arm at the elbow
 Brachioradialis - flexes the forearm at the
elbow
 Triceps brachii - extends the arm at the elbow
 Supinator - rotates the forearm laterally
(supination)
 Pronator teres - rotates the forearm medially
(pronation)
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Muscles of the Wrist,
Hand and Fingers
 Flexor carpi radialis and flexor carpi ulnaris - act
to flex and abduct the wrist.
 Palmaris longus - acts to flex the wrist.
 Flexor digitorum profundus - acts to flex the distal
joints of the fingers but not the thumb.
 Extensor carpi radialis longus and brevis - act to
extend the wrist and abduct the hand.
 Extensor carpi ulnaris - acts to extend the wrist.
 Extensor digitorum - acts to extend the fingers but
not the thumb.
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Respiratory Muscles
 Diaphragm - separates
the thoracic cavity from
the abdominal cavity; its
contraction causes
inspiration.
 External and internal
intercostals - muscles
expand and lower the ribs
during breathing.
31
Apply Your Knowledge
A patient has arrived in the office
complaining of pain when she raises her
arm. What muscle would be involved in
this action?
32
Apply Your Knowledge -Answer
A patient has arrived in the office
complaining of pain when she raises her
arm. What muscle would be involved in
this action?
The deltoid muscle acts to abduct and
extend the arm at the shoulder.
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Abdominal Muscles
 External and internal
obliques - compress
the abdominal wall.
 Transverse abdominis
- also compresses the
abdominal wall.
 Rectus abdominis acts to flex the
vertebral column and
compress the
abdominal wall.
Click for Larger View
34
Abdominal Muscles (cont.)
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Muscles of the Pectoral Girdle
 Trapezius - muscle raises the
arms and pulls the shoulders
downward.
 Pectoralis minor - muscle
pulls the scapula downward
and raises the ribs.
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Leg Muscles
 Psoas major & iliacus - flexes the thigh.
 Gluteus maximus - extends the thigh.
 Gluteus medius and minimus - abduct the
thighs and rotate them medially.
 Adductor longus and magnus - muscles adduct
the thighs and rotate them laterally.
 Biceps femoris, semitendinosus, and
semimembranosus - three muscles are known as
the hamstring group. They act to flex the leg at
the knee and extend the leg at the thigh.
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Leg Muscles (cont.)
 Rectus femoris, vastus
lateralis, vastus medialis, and
vastus intermedius - act to
extend the leg at the knee.
 Sartorius - flexes the leg at the
knee and thigh and abducts the
thigh, rotating the thigh laterally
but rotating the lower leg
medially.
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Muscles of the Ankle,
Foot, and Toes
Tibialis anterior - acts to invert the foot and point
the foot up (dorsiflexion).
Extensor digitorum longus - acts to extend the
toes and point the foot up.
Gastrocnemius - acts to flex the foot and flex the
leg at the knee.
Soleus - also acts to flex the foot.
Flexor digitorum longus - acts to flex the foot and
toes.
39
Apply Your Knowledge
Your patient complains of hurting his
hamstring when running today. You
would look at what part of the leg, and
what muscles would be involved?
40
Apply Your Knowledge -Answer
Your patient complains of hurting his
hamstring when running today. You
would look at what part of the leg, and
what muscles would be involved?
You would look at the back of his leg, and the
muscles involved would be the biceps femoris,
semitendinosus, and semimembranosus. These three
muscles are known as the hamstring group.
41
Muscle Strains and Sprains
 Warm Up – Warming up muscles for just a few
minutes before an intense activity raises muscle
temperature.
 Stretch – Stretching improves muscle performance
and should always be done after the warm up or
after exercising.
 Cool Down – Slowing down the exercise before
completely stopping prevents dizziness and
fainting.
42
Diseases and Disorders
of the Muscular System


Botulism - affects the
gastrointestinal tract
and various muscle
groups
Fibromyalgia - fairly
common condition that
causes chronic pain
primarily in joints,
muscles, and tendons


Muscular Dystrophy inherited disorder
characterized by
muscle weakness and a
loss of muscle tissue
Myasthenia gravis patients experience
muscle weakness
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Diseases and Disorders
of the Muscular System


Rhabdomyolysis a condition in which
the kidneys have
been damaged
related to serious
muscle injuries
Tetanus commonly called
lockjaw

Trichinosis - an
infection caused by
parasites (worms)
44
Apply Your Knowledge
The doctor has told your patient that his
son has muscular dystrophy disorder.
What is muscular dystrophy?
45
Apply Your Knowledge -Answer
The doctor has told your patient that his
son has muscular dystrophy disorder.
What is Muscular dystrophy?
Muscular dystrophy is an inherited disorder
characterized by muscle weakness and a loss
of muscle tissue.
46
Summary
Medical Assistant
Skeletal muscle works in conjunction with the
skeletal system to produce movement.
You must understand the muscular system in order to
give muscular injections, prepare patients for massage
therapy, demonstrate ambulatory techniques, and
assist in the care of sprains and strains.
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End of Chapter
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