CHAPTER
25
The Muscular
System
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25-2
Learning Outcomes (cont.)
25.1 Describe the functions of muscle.
25.2 Compare the three types of muscle tissue
including their locations and characteristics.
25.3 Explain how muscle tissue generates energy.
25.4 Describe the structure of a skeletal muscle.
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25-3
Learning Outcomes (cont.)
25.5 Recognize the terms origin and insertion.
25.6 Identify the major skeletal muscles of the
body, giving the action of each.
25.7 Summarize the changes that occur to the
muscular system as a person ages.
25.8 Describe the causes, signs and symptoms,
and treatments of various diseases and
disorders of the muscular system.
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25-4
Introduction
• Muscles contract and relax to cause
movement
•
600 individual muscles in the body
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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25-5
Functions of Muscle
• The ability to contract enables muscles to
– Allow movement
– Provide stability
– Control body openings and passages
– Warm the body
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25-6
Functions of Muscle (cont.)
•
Skeletal muscles
Attach to bones by tendons
– Contractions result in movement
–
•
Smooth muscle – contractions move organ
contents
•
Cardiac muscle – contractions pump blood
from the heart
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25-7
Functions of Muscle (cont.)
• Stability
• Heat Production
– Hold bones tightly
together
– Small muscles hold
vertebrae together
– Heat is released
when muscles
contract
– Helps maintain a
normal temperature
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25-8
Control of Body Openings and Passages
• Sphincters
– Valve-like structures
– Control movement in and out of
passages
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25-9
Apply Your Knowledge
True or False:
ANSWER:
tendons
___
F Skeletal muscles are attached to bones by ligaments.
___
T Contractions of smooth muscle produce movement of
organ contents.
___
T Cardiac muscle produces atrial and ventricular
contractions.
in and out
___
F Sphincters control movement of substances out of
passages.
___
F Heat is released as muscles relax.
contract
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25-10
Types of Muscle Tissue
• Muscle cells or myocytes – muscle
fibers
– Sarcolemma
– Sarcoplasm
– Sarcoplasmic reticulum
– Myofibrils
• Long structures in sarcoplasm
• Striations – arrangement of filaments
Muscle
structure
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25-12
Types of Muscle Tissue (cont.)
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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25-13
Skeletal Muscle
• Skeletal muscle fibers
– Contract in response to the neurotransmitter
acetylcholine
– After contraction, muscles release the
enzyme acetylcholinesterase
• Breaks down acetylcholine
• Allows muscle to relax
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25-14
Smooth Muscle
• Multiunit smooth muscles – respond to
neurotransmitters and hormones
• Visceral smooth muscles
– Responds to neurotransmitters ~
acetylcholine and norepinephrine
– Stimulate each other to contract ~ peristalsis
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25-15
Cardiac Muscle
• Intercalated discs
– Connect groups of cardiac muscle
– Allow the heart to work as a pump
• Self-exciting
• Responds to neurotransmitters
– Acetylcholine
– Norepinephrine
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25-16
Apply Your Knowledge
Match the following:
ANSWER:
A. Skeletal Muscle
C Self-exciting
___
B. Smooth muscle
A Contract in response to acetylcholine
___
C. Cardiac muscle
___
B Stimulate each other to contract
___
B Peristalsis
C Slowed by acetylcholine
___
A Voluntary movement
___
Very
Good!
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25-17
Production of Energy for Muscle
• ATP
•
Muscle cells make ATP by
– Creatine phosphate ~ rapid production of
energy
– Aerobic respiration ~ uses body’s store of
glucose
– Lactic acid production from pyruvic acid
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25-18
Oxygen Debt
Strenuous use of skeletal muscles depletes
cells of oxygen
Pyruvic Acid
Lactic acid
To liver for conversion to
glucose, requiring more energy
and oxygen to make ATP
Muscle fatigue
Oxygen debt
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25-19
Muscle Fatigue
•
Loses ability to contract
•
Causes
– Accumulation of lactic acid
– Interruption of the blood supply
– Acetylcholine not released by motor neuron
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25-20
Apply Your Knowledge
Match the following:
ANSWER:
E Rapid production of energy
___
C Needed for sustained or
___
repeated muscle contractions
___
D Uses body’s store of glucose
___
A Muscle fatigue
B With strenuous exercise,
___
converts to lactic acid
A.
Lactic acid
B.
Pyruvic acid
C.
ATP
D.
Aerobic
respiration
E.
Creatine
phosphate
Yippee!
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25-21
Structure of Skeletal Muscles
•
Skeletal muscles – the major organs of the
muscular system
•
Composition
– Connective tissue
– Skeletal muscle tissue
– Blood vessels
– Nerves
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25-22
Structure of Skeletal Muscles (cont.)
• Connective tissue coverings
– Fascia
– Epimysium
– Tendon
– Perimysium
– Aponeruosis
– Endomysium
Muscle
structure
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25-23
Apply Your Knowledge
Match the following:
ANSWER:
D Thin covering under the fascia
__
that surrounds the muscle
E Separates muscles from each
__
other
A. Tendon
B. Perimysium
C. Aponeurosis
__
A Connects muscles to bones
D. Epimysium
B Divides a muscle into sections
__
called fascicles
E. Fascia
F. Endomysium
F Surrounds individual muscle cells
__
__
C Attaches muscles to other
muscles
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25-24
Attachments and Actions of Skeletal
Muscles
•
Attachment types
– Origin ~ for a less
movable bone
– Insertion ~ for a
more movable bone
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25-25
Attachments and Actions of Skeletal
Muscles (cont.)
• Movement
– Prime mover (agonist) ~ responsible for
most of the movement
– Synergists ~ help the prime mover by
stabilizing joints
– Antagonist ~ produces movement opposite
to prime mover
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25-26
Attachments and Actions of Skeletal
Muscles (cont.)
• Flexion
• Plantar flexion
• Extension
• Abduction
• Hyperextension
• Adduction
• Dorsiflexion
Figure of Body
Movements
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25-28
Attachments and Actions of Skeletal
Muscles (cont.)
• Rotation
• Circumduction
• Pronation
Supination
• Supination
Pronation
Rotation
Circumduction
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25-29
Attachments and Actions of Skeletal
Muscles (cont.)
• Inversion
• Protraction
• Eversion
• Elevation
• Retraction
• Depression
Figure of
movements
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25-31
Apply Your Knowledge
True or false?
ANSWER:
F An agonist is the muscle that produces a movement
opposite to a prime mover.
antagonist
T Synergists stabilize joints.
T Origin is an attachment site for the less moveable
bone during muscle contraction.
T Insertion is an attachment site for the more moveable
bone during muscle contraction.
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25-32
Major Skeletal Muscles
•
Name often describes muscle by
– Location
– Size
– Action
– Shape
– Number of attachments
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25-34
Muscles of the Head
• Sternocleidomastoid
• Splenius capitis
• Muscles of facial
expression
– Frontalis
– Orbicularis oris
• Muscles of the jaw
• Masseter
• Temporalis
– Orbiuclaris oculi
– Zygomaticus
– Platysma
Skeletal
muscles
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25-35
Arm Muscles
•
Pectoralis major
•
Subscapularis
•
Latissimus dorsi
•
Infraspinatus
•
Deltoid
Skeletal
muscles
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25-36
Arm Muscles (cont.)
•
Biceps brachii
•
Brachialis
•
Brachioradialis
•
Triceps brachii
•
Supinator
•
Pronator teres
Skeletal
muscles
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25-37
Muscles of the Wrist, Hand, and Fingers
• Flexor carpi radilas
• Felxor carpi ulnaris
• Palmaris longus
• Flexor digitorum
profundus
• Extensor carpi radialis
longus and brevis
• Extensor carpi ulnairs
• Extensor digitorum
Diagram
of hand
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25-39
Respiratory Muscles
• Diaphragm
– Separates thoracic and abdominal cavities
– Contracts for inspiration
• External and internal intercostals – expand
and lower the ribs
For
diagram
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25-40
Skeletal Muscles (cont.)
• Abdominal
muscles
• Muscles of the
Pectoral Girdle
– External and
internal obliques
– Trapezius
– Pectoralis minor
– Transverse
abdominis
– Rectus abdominis
For
diagram
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25-42
Leg Muscles
• Iliopsoas major
• Gluteus maximus
• Gluteus medius and minimus
• Adductor longus and magnus
Skeletal
muscles
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25-43
Leg Muscles (cont.)
• Biceps femoris, semitendinosus, and
semimembranosus
• Rectus femoris, vastus lateralis, vastus
medialis, and vastus intermedius
• Sartoris
Skeletal muscles
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25-44
Ankle, Foot, and Toe Muscles
•
Tibialis anterior
•
Extensor digitorum longus
•
Gastrocnemius
•
Soleus
•
Flexor digitorum longus
Skeletal
muscles
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25-45
Apply Your Knowledge
ANSWER:
Matching:
C raises the eyebrows
A. Gluteus maximus
B. Intercostals
F chewing
B expand and lower ribs
E compress the abdominal wall
A extends the thigh
D extends the leg at the knee
C. Frontalis
D. Quadriceps group
E. Obliques
F. Masseter
Bravo!
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25-46
Aging and the Musculoskeletal System
• Speed and strength of muscle contractions
decrease
• Aging
– Decreased dexterity and gripping ability
– Decreased mobility
• Assistive devices helpful
• Routine exercise
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25-47
Diseases and Disorders of the Muscular
System
Disease
Description
Botulism
Affects the gastrointestinal tract and
various muscle groups
Fibromyalgia
Fairly common condition that causes
chronic pain primarily in joints, muscles,
and tendons
Inherited disorder characterized by muscle
weakness and a loss of muscle tissue
Autoimmune condition in which patients
experience muscle weakness and loss of
muscle tissue
Muscular
dystrophy
Myasthenia
gravis
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25-48
Diseases and Disorders of the Muscular
System (cont.)
Disease
Description
Rhabdomyolysis
Kidneys become damaged because of
toxins released from muscle cells after
serious muscle injuries
Tendonitis
Painful inflammation of a tendon and the
tendon-muscle attachment to a bone
Tetanus
(lockjaw)
Muscle spasms in the jaw, keck and
facial muscles; high mortality rate
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25-49
Diseases and Disorders of the Muscular
System (cont.)
Disease
Torticollis
(wryneck)
Trichinosis
Description
A cervical deformity in which the head
bends toward the affected side while the
chin rotates to the opposite side
An infection caused by parasites
ingested by eating undercooked meat
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25-50
Apply Your Knowledge
1. What changes occur to the muscular system as
a result of aging?
ANSWER: Speed and strength of muscle contractions
decrease with aging.
The aging process results in:
• Decreased dexterity and gripping ability
• Decreased mobility
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25-51
Apply Your Knowledge
ANSWER:
True or False: Fibromyalgia
F Botulism is a condition resulting in chronic pain in joints,
muscles and tendons.
T Kidney damage due to toxins released by serious
muscle injuries is the condition called rhabdomyolysis.
T Tetanus is caused by a toxin and causes muscle
spasms in the jaw, neck, and facial muscles.
Torticollis
F Lockjaw is caused by spasm or shortening of the
sternocleidomastoid muscle.
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25-52
In Summary
25.1 The functions of muscles include movement,
stability, control of body openings and
passages, and the production of heat. Valvelike muscular structures called sphincters
control passage of substances into and out
of organs like the stomach and bladder.
.
25.2 The three types of muscle tissue are striated,
voluntary skeletal muscle; smooth,
involuntary visceral muscle; and specialized
striated and involuntary cardiac muscle.
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25-53
In Summary (cont.)
25.3 There are three ways muscles create energy.
Creatine phosphate, aerobic respiration, and
lactic acid production.
25.4 Skeletal muscle is composed of connective
tissues, skeletal muscle tissue, blood
vessels, and nerves. The coverings of
skeletal muscles include fascia, tendon,
aponeurosis, epimysium, perimysium, and
endomysium.
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in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
25-54
In Summary (cont.)
25.5 The origin of a muscle is the attachment site
of the muscle to the less moveable bone
during muscle contraction. The insertion of a
muscle is the attachment site for the muscle
to the more moveable bone during muscle
contraction.
25.6 The major muscles of the head and the upper
extremity, major respiratory muscles,
abdominal muscles, pectoral girdle muscles
and those of the lower extremity are covered
in this learning outcome.
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25-55
In Summary (cont.)
22.7 The common diseases of aging include
arthritis, fractures, osteoporosis, and
muscular decline. Aging causes a decline in
strength and speed of muscle contractions.
Dexterity and gripping abilities lessen and
mobility often decreases related to skeletal
and muscular decline.
22.8 There are many common diseases and
disorders of the muscular system with varied
signs, symptoms, and treatments.
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in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
25-56
End of Chapter 25
Everyone has a ‘risk muscle.’
You keep it in shape by
trying new things. If you
don’t, it atrophies. Make a
point of using it at least once
a day.
~Roger von Oech
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in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.