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Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
Cardiac Muscle
• Found only in the heart• Striated muscle • Under involuntary control• Has specialized cells that provide a
stimulus for contraction
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
Assessment Techniques
• Reflex tests• Joint motion measured using a
protractor• Blood tests• Electromyography tests• Muscle biopsy
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
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
Copyright 2003 by Mosby, Inc. All rights reserved.
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