1. CHAPTER 14 MUSCULAR SYSTEM
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2. Structure and Function
The human body has more than 600 muscles
The functions of the muscular system
Aid in movement
Provide and maintain posture
Protect internal organs
Provide movement of blood, food, and waste products through the body
Open and close body openings
Produce heat
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3. Table 14-1 Types of Muscle Tissue
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Skeletal Muscle
Makes up more than 40% of a person’s body weight
Looks striated, or banded, under the microscope
Skeletal muscles have three parts
Origin is one end of the muscle, attached to the less movable part of the bone
Insertion is the other end of the muscle, attached to the more movable part of the bone
The action, or body, is the thick middle part of the muscle
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5. Figure 14-5 Basic Types of Muscle Movement
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Visceral Muscle
Lines various hollow organs
Makes up the walls of blood vessels
Found in the tubes of the digestive system
Smooth and has no striations
Controlled by the autonomic nervous system
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Cardiac Muscle
Found only in the heart
Striated muscle
Under involuntary control
Has specialized cells that provide a stimulus for contraction
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Muscle Contraction
Isotonic contraction is muscle shortening that produces movement
Muscle tone or tonus is a state of partial contraction that maintains a person’s posture
Isometric contraction does not cause muscle shortening or movement
A twitch is a quick, jerky contraction of a whole muscle from one stimulus
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9. Muscle Contraction (continued)
Tetanic contraction is more sustained than a twitch and is caused by many stimuli in rapid succession
Fibrillation is uncoordinated contraction of muscle fibers
Convulsions are contractions of groups of muscles in an abnormal manner
Spasms are involuntary, sudden, and prolonged contractions
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10. Figure 14-8 Sliding Filament Theory
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11. Assessment Techniques
Reflex tests
Joint motion measured using a protractor
Blood tests
Electromyography tests
Muscle biopsy
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12. Disorders of the Muscular System
Back pain
From weakened muscles around the spine in the lower back
Contracture
A condition in which muscles remain contracted as a joint loses flexibility and ligaments and tendons shorten
Muscle cramp
A sudden involuntary contraction of a muscle producing pain
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13. Disorders of the Muscular System (continued)
Muscular dystrophy
A group of genetic diseases involving painless, gradual atrophy of muscle tissue
Fibromyalgia
A group of muscle disorders affecting the tendons, ligaments, and other fibrous tissues
Gangrene
Caused by Clostridium bacteria that kill muscle tissue
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14. Disorders of the Muscular System (continued)
Hernia
The abnormal protrusion of a body part into another body area
Myasthenia gravis
A condition in which nerve impulses are not transmitted normally from the brain to the muscles
Poliomyelitis
A viral infection that results in paralysis of muscles
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15. Disorders of the Muscular System (continued)
Muscle sprain
A traumatic injury to the tendons, muscles, or ligaments of a joint
Muscle strain
Torn or stretched tendons and muscles, causing pain
Pes planus
Called “flatfoot” or “fallen arches,” may be congenital or result from weakened foot muscles
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16. Disorders of the Muscular System (continued)
Tetanus
Commonly called “lockjaw,” is caused by a bacterial infection
Trichinosis
A parasitic infection caused by eating undercooked pork
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17. Issues and Innovations
Sports medicine
– Treating sports injuries
– Directing healthful development and training of athletes
– Biomechanics
• Fitness fad
– Importance of regular exercise for good health
– Exercise obsession
Copyright 2003 by Mosby, Inc. All rights reserved.