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Essentials of Human Anatomy & Physiology
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slides 6.1 – 6.17
Seventh EditionElaine N. Marieb
Chapter 6The Muscular System
Lecture Slides in PowerPoint by Jerry L. Cook
The Muscular SystemThe Muscular System
Slide 6.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Muscles are responsible for all types of body movement
Three basic muscle types are found in the body
Skeletal muscle
Cardiac muscle
Smooth muscle
Characteristics of MusclesCharacteristics of Muscles
Slide 6.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Muscle cells are elongated (muscle cell = muscle fiber)
Contraction of muscles is due to the movement of microfilaments
All muscles share some terminology
Prefix myo refers to muscle
Prefix mys refers to muscle
Prefix sarco refers to flesh
Skeletal Muscle CharacteristicsSkeletal Muscle Characteristics
Slide 6.3Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Most are attached by tendons to bones
Cells are multinucleate
Striated – have visible banding
Voluntary – subject to conscious control
Cells are surrounded and bundled by connective tissue
Connective Tissue Wrappings ofConnective Tissue Wrappings ofSkeletal MuscleSkeletal Muscle
Slide 6.4aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Endomysium – around single muscle fiber
Perimysium – around a fascicle (bundle) of fibers Figure 6.1
Connective Tissue Wrappings ofConnective Tissue Wrappings ofSkeletal MuscleSkeletal Muscle
Slide 6.4bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Epimysium – covers the entire skeletal muscle
Fascia – on the outside of the epimysium
Figure 6.1
Skeletal Muscle AttachmentsSkeletal Muscle Attachments
Slide 6.5Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Epimysium blends into a connective tissue attachment Tendon – cord-like structure
Aponeuroses – sheet-like structure
Sites of muscle attachment Bones
Cartilages
Connective tissue coverings
Smooth Muscle CharacteristicsSmooth Muscle Characteristics
Slide 6.6Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Has no striations
Spindle-shaped cells
Single nucleus
Involuntary – no conscious control
Found mainly in the walls of hollow organs
Figure 6.2a
Cardiac Muscle CharacteristicsCardiac Muscle Characteristics
Slide 6.7Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Has striations
Usually has a single nucleus
Joined to another muscle cell at an intercalated disc
Involuntary
Found only in the heart Figure 6.2b
Function of MusclesFunction of Muscles
Slide 6.8Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Produce movement
Maintain posture
Stabilize joints
Generate heat
Microscopic Anatomy of SkeletalMicroscopic Anatomy of SkeletalMuscleMuscle
Slide 6.9aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cells are multinucleate
Nuclei are just beneath the sarcolemma
Figure 6.3a
Microscopic Anatomy of SkeletalMicroscopic Anatomy of SkeletalMuscleMuscle
Slide 6.9bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sarcolemma – specialized plasma membrane
Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum
Figure 6.3a
Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle
Slide 6.10aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Myofibril
Bundles of myofilaments
Myofibrils are aligned to give distrinct bands
I band = light band
A band = dark band
Figure 6.3b
Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle
Slide 6.10bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sarcomere Contractile unit of a muscle fiber
Figure 6.3b
Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle
Slide 6.11aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Organization of the sarcomere Thick filaments = myosin filaments
Composed of the protein myosin
Has ATPase enzymes
Figure 6.3c
Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle
Slide 6.11bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Organization of the sarcomere Thin filaments = actin filaments
Composed of the protein actin
Figure 6.3c
Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle
Slide 6.12aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Myosin filaments have heads (extensions, or cross bridges)
Myosin and actin overlap somewhat
Figure 6.3d
Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle
Slide 6.12bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
At rest, there is a bare zone that lacks actin filaments
Sarcoplasmic reticulum (SR) – for storage of calcium
Figure 6.3d
Properties of Skeletal Muscle Properties of Skeletal Muscle ActivityActivity
Slide 6.13Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Irritability – ability to receive and respond to a stimulus
Contractility – ability to shorten when an adequate stimulus is received
Nerve Stimulus to MusclesNerve Stimulus to Muscles
Slide 6.14Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Skeletal muscles must be stimulated by a nerve to contract
Motor unit One neuron
Muscle cells stimulated by that neuron Figure 6.4a
Nerve Stimulus to MusclesNerve Stimulus to Muscles
Slide 6.15aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Neuromuscular junctions – association site of nerve and muscle
Figure 6.5b
Nerve Stimulus to MusclesNerve Stimulus to Muscles
Slide 6.15bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Synaptic cleft – gap between nerve and muscle Nerve and
muscle do not make contact
Area between nerve and muscle is filled with interstitial fluid Figure 6.5b
Transmission of Nerve Impulse to Transmission of Nerve Impulse to MuscleMuscle
Slide 6.16aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Neurotransmitter – chemical released by nerve upon arrival of nerve impulse
The neurotransmitter for skeletal muscle is acetylcholine
Neurotransmitter attaches to receptors on the sarcolemma
Sarcolemma becomes permeable to sodium (Na+)
Transmission of Nerve Impulse to Transmission of Nerve Impulse to MuscleMuscle
Slide 6.16bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sodium rushing into the cell generates an action potential
Once started, muscle contraction cannot be stopped
The Sliding Filament Theory of The Sliding Filament Theory of Muscle ContractionMuscle Contraction
Slide 6.17aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Activation by nerve causes myosin heads (crossbridges) to attach to binding sites on the thin filament
Myosin heads then bind to the next site of the thin filament
Figure 6.7
The Sliding Filament Theory of The Sliding Filament Theory of Muscle ContractionMuscle Contraction
Slide 6.17bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
This continued action causes a sliding of the myosin along the actin
The result is that the muscle is shortened (contracted)
Figure 6.7
Types of Ordinary Body MovementsTypes of Ordinary Body Movements
Slide 6.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Flexion
Extension
Rotation
Abduction
Circumduction
Body MovementsBody Movements
Slide 6.33Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.13
Special MovementsSpecial Movements
Slide 6.34Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Dorsifelxion
Plantar flexion
Inversion
Eversion
Supination
Pronation
Opposition
Types of MusclesTypes of Muscles
Slide 6.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Prime mover – muscle with the major responsibility for a certain movement
Antagonist – muscle that opposes or reverses a prime mover
Synergist – muscle that aids a prime mover in a movement and helps prevent rotation
Fixator – stabilizes the origin of a prime mover
Naming of Skeletal MusclesNaming of Skeletal Muscles
Slide 6.36aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Direction of muscle fibers
Example: rectus (straight)
Relative size of the muscle
Example: maximus (largest)
Naming of Skeletal MusclesNaming of Skeletal Muscles
Slide 6.36bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Location of the muscle
Example: many muscles are named for bones (e.g., temporalis)
Number of origins
Example: triceps (three heads)
Naming of Skeletal MusclesNaming of Skeletal Muscles
Slide 6.37Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Location of the muscles origin and insertion
Example: sterno (on the sternum)
Shape of the muscle
Example: deltoid (triangular)
Action of the muscle
Example: flexor and extensor (flexes or extends a bone)
Head and Neck MusclesHead and Neck Muscles
Slide 6.38Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.14
Trunk MusclesTrunk Muscles
Slide 6.39Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.15
Deep Trunk and Arm MusclesDeep Trunk and Arm Muscles
Slide 6.40Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.16
Muscles of the Pelvis, Hip, and ThighMuscles of the Pelvis, Hip, and Thigh
Slide 6.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.18c
Muscles of the Lower LegMuscles of the Lower Leg
Slide 6.42Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.19
Superficial Muscles: AnteriorSuperficial Muscles: Anterior
Slide 6.43Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.20
Superficial Muscles: PosteriorSuperficial Muscles: Posterior
Slide 6.44Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.21