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6:5 Muscular System
600+ muscles in the body
Bundles of muscle fibers held together with connective tissue
Some attach to the bones by strong cords called tendons
Other attach to the bones tough sheet-like membrane called fascia
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Properties of Muscles
Excitability/irritability
Ability to respond to a stimulus/nerve impulse
Contractibility
Can become short & thick which allows for movement
Extensibility
Ability to be stretched
Elasticity
Allow muscle to return to original shape
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Kinds of Muscles
Cardiac
Forms the walls of the heart
Visceral or smooth
Found in internal organs (digestive, respiratory tracts) & allows for movement within these organs
Skeletal
Attaches to bone to allow movement of the body
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Functions of Muscles
Attach bones to provide voluntary movement
Produce heat and energy
Help maintain posture
Protect internal organs
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5. Actions or Movements of Muscles
Adduction
Moving a body part toward the midline
Abduction
Moving a body part away from the midline
Flexion
Bending a body part
Extension
Straightening a body part
Rotation
Turning a body part from side to side
Circumduction
Moving in a circle such as the arm at the shoulder joint
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Muscle Tone
Allows for state of readiness
State of being partially contracted at all times
Atrophy: Loss of muscle tone
Muscles shrink & become smaller
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7. Muscle Tone (continued)
Contracture: severe tightening of muscles resulting in bending of a joint
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8. Diseases and Abnormal Conditions
Fibromyalgia
Continuous pain in muscles
Muscular dystrophy
Chronic, progressive muscle atrophy
Myasthenia gravis
Nerve impulses do not reach muscle properly leading to muscles weakness & paralysis
Muscle spasms or cramps
Painful involuntary contraction of a muscle
Strain
Overstretching of a muscle
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