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Copyright © 2009 Pearson Education, Inc. The Muscular System Skeletal Muscle Muscle anatomy Muscle contraction
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Copyright © 2009 Pearson Education, Inc.
The Muscular System
Skeletal Muscle Muscle anatomy Muscle contraction
Copyright © 2009 Pearson Education, Inc.
The Muscular System
Figure 6.2 (1 of 2)
Pectoralis major• Draws arm forwardand toward the body
Serratus anterior• Helps raise arm• Contributes to pushes• Draws shoulder blade forward
Biceps brachii• Bends forearm at elbow
Rectus abdominus• Compresses abdomen• Bends backbone• Compresses chest cavity
External oblique• Lateral rotation of trunk• Compresses abdomen
Adductor longus• Flexes thigh• Rotates thigh laterally• Draws thigh toward body
Sartorius• Bends thigh at hip• Bends lower leg at knee• Rotates thigh outward
Quadriceps group• Flexes thigh at hips• Extends leg at knee
Tibialis anterior• Flexes foot toward knee
Copyright © 2009 Pearson Education, Inc.
The Muscular System
Figure 6.2 (2 of 2)
Deltoid• Raises armTrapezius• Lifts shoulder blade• Braces shoulder• Draws head backTriceps brachi• Straightens forearmat elbowLatissimus dorsi• Rotates and draws arm backward and toward bodyGluteus maximus• Extends thigh• Rotates thigh laterally
Achilles tendon• Connectsgastrocnemiusmuscle to heel
Hamstring group• Draws thigh backward• Bends kneeGastrocnemius• Bends lower leg atknee• Bends foot away fromknee
Copyright © 2009 Pearson Education, Inc.
Muscle Structure
Fascicles: bundles; CT covering on each one
Muscle fibers: muscle cells
Figure 6.3
Tendon
Bone
Whole muscle
Muscle bundle (fascicle)surrounded by connectivetissue (fascia)
Single muscle cell(fiber)
Copyright © 2009 Pearson Education, Inc.
Skeletal Muscle Contractile Unit
Figure 6.5a–b
Copyright © 2009 Pearson Education, Inc.
Nerve Activation of Individual Muscle Cells
Figure 6.6
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Calcium Initiates the Sliding Filament Mechanism
Figure 6.7
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Mechanism of Muscle Contraction
Figure 6.8
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Muscle Relaxation
Nerve activation ends, contraction ends Calcium pumped back into sarcoplasmic
reticulum Calcium removed from troponin Myosin binding site covered No calcium = no cross-bridges
Copyright © 2009 Pearson Education, Inc.
Energy Required for Muscle Activity
Principle source of energy: ATP ATP is replenished by a variety of means
Creatine phosphate Stored glycogen Aerobic metabolism of glucose, fatty acids,
and other high-energy molecules
