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
261 List the functions of muscle.
262 Explain how muscle tissue generates energy.
263 List the three types of muscle tissue and describe
the locations and characteristics of each.
264 Describe how smooth muscle produces peristalsis.
265 Describe the structure of a skeletal muscle.
2
The Muscular System
Objectives (cont.)
267 List and define the various types of body
movements produced by skeletal muscles.
268 Define the terms origin and insertion.
269 List the major skeletal muscles of the body and
give the action of each.
2610 Describe various disorders and diseases of the
muscular system.
3
Introduction
Bones and joints do By alternating between
not themselves
contraction and
produce movement.
relaxation, muscles
cause bones and
The human body has
supported structures to
more than 600
move.
individual muscles
You will focus on the differences among three muscle tissue
types, the structure of skeletal muscles, muscle actions, and
the names of skeletal muscles.
4
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
Click for
Larger View
5
Skeletal Muscle
6
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.
7
Functions of Muscle
Stability:
Muscles hold your bones together to
stabilize joints.
Small muscles hold your vertebrae
together to stabilize your spinal column.
8
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
9
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.
10
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.
12
Production of Energy
for Muscle
ATP (adenosine
Muscle cells must have
triphosphate), a type of
three ways to store or
chemical energy, is
make this substance:
needed for sustained or
repeated muscle
Creatine phosphate
contractions.
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.
14
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
15
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.
17
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
18
Connective Tissue Coverings
Fascia covers entire skeletal muscles and separates them
Fascia
from each other.
Tendon a tough, cordlike structure made of fibrous
Tendon
connective tissue that connects muscles to bones.
Aponeurosis a tough, sheetlike structure made of fibrous
Aponeurosis
connective tissue that attaches muscles to other muscles.
Epimysium a thin covering that is just deep (underneath)
Epimysium
to the fascia of a muscle that surrounds the entire muscle.
Perimysium connective tissue divides a muscle into
Perimysium
sections called fascicles.
fascicles
Endomysium covering of connective tissue surrounds
Endomysium
individual muscle cells.
19
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
20
Body Movements
Flexion – Bending a
Flexion
body part
Extension –
Straightening a body
part
Hyperextension –
Hyperextension
Extending a body part
past the normal
anatomical position
Dorsiflexion – Pointing
Dorsiflexion
the toes up
Plantar flexion –
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
21
Body Movements (cont.)
Circumduction
Circumduction
Moving a body part in
a circle; for example,
moving your arm in a
circular motion
Pronation – Turning the
Pronation
palm of the hand
down
Supination – Turning
Supination
the palm of the hand
up
Inversion – Turning the
Inversion
sole of the foot
medially
Eversion – Turning the
sole of the foot
laterally
Retraction – Moving a
Retraction
body part posteriorly
Protraction – Moving a
Protraction
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,
Depression
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?
24
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.
25