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CHAPTER 15 Muscles of the Body
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Sports & Injury
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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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skeletal cardiac smooth
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Unique Characteristics of Muscle
Irritability or excitability Muscle’s ability to respond to a stimulus Contractility Ability to shorten forcefully when stimulated Extensibility Ability to stretch and lengthen Elasticity Ability to recoil to its resting length when relaxed
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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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Figure 15-3 Parts of a Muscle
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Figure 15-4 Types of Muscle Movement
SYSTEM
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Smooth Muscle/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 (not under your control)
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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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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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Assessment Techniques
Joint ROM Measure using a goniometer Blood tests CPK isoenzyme test measures creatine phosphokinase (CPK) in the blood. CPK found in the heart, brain, and skeletal muscles. Measure lactic acid Electromyography tests Tests muscles through needles inserted into the muscle Muscle biopsy Used to assess for tissue disorders Muscular dystrophy, polio, necrotizing disease
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Disorders Back pain Contracture
From weakened muscles around the spine in the lower back Contracture When muscles remain contracted as a joint loses flexibility and ligaments and tendons shorten When your muscles move less, they shrink and shorten.
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Disorders of the Muscular System
Muscular dystrophy A group of genetic diseases involving painless, gradual atrophy of muscle tissue
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Disorders of the Muscular System
Gangrene Caused by Clostridium bacteria that kill muscle tissue Poliomyelitis (Polio) A viral infection that results in paralysis of muscles
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Disorders of the Muscular System
Hernia The abnormal protrusion of a body part into another body area
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Disorders of the Muscular System
Trichinosis A parasitic infection caused by eating undercooked pork or other meats
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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
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Disorders of the Muscular System
Muscle sprain A traumatic injury to the between two bones in a joint Most common is an ankle sprain Ligamentous Pull Muscle strain Torn or stretched tendons and muscles, causing pain
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Pes planus: Called “flatfoot” or “fallen arches,” may be congenital or result from weakened foot muscles Pes Planus: over-pronation High Arches: Supination
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Muscular/Skeletal Careers
Physical Therapy Occupational Therapy Orthopedic Surgery Athletic Trainer
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Lab Activity: ROM & Goniometer
ROM Goniometer Infant Reflexes Reflex Hammer
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