6 5 Muscular System 600 muscles in the

Properties of Muscles § Excitability/irritability – Ability to respond to a stimulus/nerve impulse §

Kinds of Muscles § Cardiac – Forms the walls of the heart § Visceral

Functions of Muscles § Attach bones to provide voluntary movement § Produce heat and

Actions or Movements of Muscles § Adduction – Moving a body part toward the

Muscle Tone § Allows for state of readiness § State of being partially contracted

Muscle Tone (continued) § Contracture: severe tightening of muscles resulting in bending of a

Diseases and Abnormal Conditions § Fibromyalgia – Continuous pain in muscles § Muscular dystrophy

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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 Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 1

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 Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 2

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 Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 3

Functions of Muscles § Attach bones to provide voluntary movement § Produce heat and energy § Help maintain posture § Protect internal organs Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 4

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 Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 6

Muscle Tone § Allows for state of readiness § State of being partially contracted at all times § Atrophy: Loss of muscle tone – Muscles shrink & become smaller Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 7

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 Copyright © 2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 9