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Lesson 5.1: Muscle Tissue Categories and Functions
Lesson 5.2: Skeletal Muscle Actions
Lesson 5.3: The Major Skeletal Muscles
Lesson 5.4: Common Injuries and Disorders of Muscles
The Muscular System
Lesson 5.1
Muscle Tissue Categories and
Functions
Chapter 5: The Muscular System
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• categories– skeletal– smooth – cardiac
• functions– behavioral properties– tension and types of skeletal muscle contractions
Muscle Tissue
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• skeletal– voluntary– striated
• smooth– involuntary– no striations
• cardiac– involuntary– striated– intercalated disks
Muscle Tissue Categories
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Muscle Tissue Categories
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• endomysium - surround the muscle fiber• fascicle – bundle of muscle fibers• perimysium - bundles groups of muscle fibers to
make up a fascicle• epimysium - encloses several fascicles to make up
a muscle • aponeurosis and tendons - connect muscle to
other tissues
Skeletal Muscle Organization
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Skeletal Muscle Organization
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True or False?
1. Smooth muscle is voluntary.
2. Cardiac muscle has branching fibers.
3. Smooth muscle is multinucleate.
4. Perimysium wraps fascicles to make a muscle.
5. Endomysium surrounds the muscle fibers.
Review and Assessment
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• extensibility–stretch• elasticity–snap back• irritability–respond• contractility–shorten
Behavioral Properties of Muscle
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• tension and types of skeletal muscle contraction– agonist–moves bone– antagonist–opposes the movement of the agonist
Muscle Tissue Functions
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• agonist contracts, antagonist relaxes
Concentric Contraction
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• agonist contracts while lengthening, antagonist relaxes
• the weight of the barbell causes tension of the bicep muscle causing it to lengthen against gravity
Eccentric Contraction
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• both agonist and antagonist contract
• no arm movement
Isometric Contraction
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Match these words with 1–5 below: extensibility, elasticity, irritability, contractility, agonist, antagonist.
1. respond
2. opposes movement
3. stretch
4. shorten
5. causes movement
Review and Assessment
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• Muscles generate heat when ATP is broken down for energy
• Even when not exercising, muscle generate heat which helps maintain our normal body temperature
Heat Production
Lesson 5.2
Skeletal Muscle Actions
Chapter 5: The Muscular System
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• the motor neuron – a nerve that stimulates skeletal muscle
• motor unit – a single motor neuron and all the muscles it stimulates
Skeletal Muscle
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• A muscle fiber is a long, thin cell• Each muscle fiber is composed of myofibrils• 2 types of protein filaments that reside in functional
units called sarcomeres
Thick filaments = myosin
Thin filaments = actin
Striations are caused by the arrangement of thick and thin filaments within the myofibrils
Skeletal Muscle Fibers
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• muscle contraction involves the sliding movement of the thin filaments (actin) past the thick filaments (myosin)
• sliding continues until the overlapping between the thin & thick filaments is complete.
• The myosin heads (cross bridges) interact with active sites on thin filaments making linkages between the thick and thin filament.
• * Remember that in a relaxed muscle cell, overlapping of thick and thin filaments is only slight (i.e. striations).
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What causes the sliding movement of the actin? • In order for a skeletal muscle to contract, its fibers must
first be stimulated by a motor neuron.• The process begins when a motor impulse is initiated by
the brain, travels down the spinal cord, into a motor neuron• The axon of the neuron branches into axon terminal which
then branch out to individual muscle fibers• Neuromuscular junctions link the axon terminals to the
individual muscle fibers.• Synaptic clefts are tiny gaps between the axon terminals
and the muscle fibers and are filled with interstitial fluid
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• When the nerve impulse reaches the axon terminal, the neurotransmitter acetylcholine is released
• Acetylcholine opens the ion channels, allowing Na+ to enter the muscle fiber and K+ to exit the muscle fiber
• Greater amount of sodium ions enter than potassium ions exit, creating action potential
• Action potential activates the sarcomeres causing the sliding of the actin over the myosin
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• group of muscle fibers under the control of one motor neuron
The Motor Unit
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• http://www.g-wlearning.com/healthsciences/9781619604124/student/ch05_02/identify01/story.html
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• sarcomeres shorten by actin filaments sliding along myosin filaments
Contraction of the Sarcomeres
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• action potential always causes entire motor unit muscle fibers to contract
Maximum Tension and Return to Relaxation
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• slow-twitch – long distance runners• fast-twitch - sprinters
- type IIa – intermediate in contraction speed– type Iib – contract rapidly and fatigue rapidly
Skeletal Muscle Fiber Types
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• parallel fiber arrangements– fusiform – biceps brachii– bundled – rectus abdominis– triangular – pectoralis major
• pennate fiber arrangements –
each fiber attaches obliquely to
a central tendon– unipennate – muscles in the hand– bipennate – rectus femoris– multipennate - deltoid
Skeletal Muscle Fiber Architecture
Lesson 5.3
The Major Skeletal Muscles
Chapter 5: The Muscular System
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• directional motions• head and neck muscles• trunk muscles• upper limb muscles• lower limb muscles
The Major Skeletal Muscles
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• origin – fixed end of a muscle
• insertion– movable end of a muscle
Skeletal Muscle Attachments
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• flexion• extension• hyperextension• dorsiflexion• plantar flexion
Sagittal Plane Movements
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• abduction• adduction• inversion• eversion• radial deviation• ulnar deviation
Frontal Plane Movements
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• medial rotation• lateral rotation• pronation• supination
Transverse Plane Movements
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• circumduction• opposition
Multiplanar Movements
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True or False?
1. Circumduction is a multiple plane movement.
2. Supination is a multiple plane movement.
3. The insertion is the fixed end of a muscle.
4. Extension is a sagittal plane movement.
5. Adduction is a frontal plane movement.
Review and Assessment
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Head and Neck Muscles
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Trunk Muscles
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Upper Limb Muscles
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Lower Limb Muscles
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Match these words with 1–4 below: head, trunk, upper limb, lower limb.
1. temporalis
2. brachioradialis
3. external oblique
4. biceps femoris
Review and Assessment
Lesson 5.4
Common Injuries and Disorders of
Muscles
Chapter 5: The Muscular System
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• strain–overstretched muscle– grade I, II, III
• contusion–bruised muscle– myositis ossificans
• cramps–spasming muscle• delayed onset muscle soreness–tear
Muscle Injuries
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• tendinitis–inflamed tendon
• tendinosis–degeneration of a tendon
Tendon Injuries
Val Thoermer/Shutterstock.com
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• rotational injury at shoulder• overuse of elbow• shin splints• whiplash
Joint Injuries
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• muscular dystrophy• hernia
Muscle Disorders
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True or False?
1. Tendinitis is muscle strain.
2. A contusion is a bruise.
3. Whiplash is a joint injury.
4. A hernia is a tendon injury.
5. A strain is an over stretch of a tendon.
Review and Assessment
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