5 The Muscular System

5
The Muscular
System
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
Chapter 5: The Muscular System
Lesson 5.1
Muscle Tissue Categories
and Functions
Muscle Tissue
• categories
– skeletal
– smooth
– cardiac
• functions
– behavioral properties
– tension and types of skeletal muscle contractions
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Muscle Tissue Categories
• skeletal
– voluntary
– striated
• smooth
– involuntary
– no striations
• cardiac
– involuntary
– striated
– intercalated disks
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Muscle Tissue Categories
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Skeletal Muscle Organization
• sarcolemma and endomysium surrounds the
muscle fiber
• perimysium bundles groups of muscle fibers to
make up a fascicle
• epimysium encloses several fascicles to make up
a muscle
• aponeurosis connects muscle to other tissues
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Skeletal Muscle Organization
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Review and Assessment
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.
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Behavioral Properties of Muscle
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extensibility–stretch
elasticity–snap back
irritability–respond
contractility–shorten
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Muscle Tissue Functions
• tension and types of skeletal muscle contraction
– agonist–moves bone
– antagonist–opposes the movement of the agonist
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Concentric Contraction
• agonist contracts,
antagonist relaxes
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Eccentric Contraction
• agonist contracts while
lengthening, antagonist
relaxes
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Isometric Contraction
• both agonist and
antagonist contract
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Review and Assessment
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
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Chapter 5: The Muscular System
Lesson 5.2
Skeletal Muscle Actions
Skeletal Muscle
• the motor unit
• skeletal fiber types
• muscular strength, power, and endurance
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The Motor Unit
• group of muscle fibers under the control of one
motor neuron
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Generating Action Potentials
• acetylcholine crosses the synaptic cleft at the
neuromuscular junction
• depolarization takes place on muscle fiber
• action potential begins
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Contraction of the Sarcomeres
• sarcomeres shorten by actin filaments sliding
along myosin filaments
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Maximum Tension and Return to
Relaxation
• action potential always causes entire motor unit
muscle fibers to contract
• all-or-none law
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Review and Assessment
True or False?
1. An action potential causes one half of the fibers in
the motor unit to contract.
2. Acetylcholine crosses the synaptic cleft at the
neuromuscular junction.
3. The sarcomeres lengthen by myosin filaments
sliding over actin filaments.
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Skeletal Muscle Fiber Types
• slow-twitch
• fast-twitch
– type IIa
– type IIb
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Skeletal Muscle Fiber Architecture
• parallel fiber arrangements
– fusiform (biceps brachii)
– bundled (rectus abdominis)
– triangular (pectoralis major)
• pennate fiber arrangements
– unipennate (extensor digitorum)
– bipennate (rectus femoris)
– multipennate (deltoid)
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Muscular Strength
• rotary force that muscles can produce at a joint
– the maximum weight you can lift is a measurement of
muscular strength
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Muscle Power
• force x velocity
– how fast you can sprint is a measurement of muscle
power
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Muscle Endurance
• muscle tension/time
– how far you can run is a measurement of muscle
endurance
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Review and Assessment
Match these words with 1–5 below: muscle
endurance, muscular strength, muscle power,
Type I, Type IIb.
1. force x velocity
2. muscle tension/time
3. rotary force that muscles can produce at a joint
4. slow twitch, slow fatigue
5. fast twitch, fast fatigue
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Chapter 5: The Muscular System
Lesson 5.3
The Major Skeletal
Muscles
The Major Skeletal Muscles
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directional motions
head and neck muscles
trunk muscles
upper limb muscles
lower limb muscles
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Skeletal Muscle Attachments
• origin
– fixed end of a muscle
• insertion
– movable end of a muscle
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Sagittal Plane Movements
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flexion
extension
hyperextension
dorsiflexion
plantar flexion
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Frontal Plane Movements
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abduction
adduction
inversion
eversion
radial deviation
ulnar deviation
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Transverse Plane Movements
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medial rotation
lateral rotation
pronation
supination
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Multiplanar Movements
• circumduction
• opposition
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Review and Assessment
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.
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Head and Neck Muscles
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Head and Neck Muscles
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Frontalis: raises eyebrows, wrinkles forehead
Orbicularis oculi: closes eyes, enables squinting
Nasalis: modifies size of nostrils
Orbicularis oris: closes lips, kissing motion
Zygomaticus: the “smiling muscle”
Platysma: pulls corners of mouth down, opens
mouth wide
• Masseter: closes the jaw
• Temporalis: assists the masseter with closing jaw
• Sternocleidomastoid: flexion and rotation of head
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Trunk Muscles
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Trunk Muscles
• Pectoralis major: adduction and flexion of the arm
• Rectus abdominis: flexion/lateral flexion of trunk
• External oblique: flexion/lateral flexion/rotation
trunk
• Internal oblique: flexion/lateral flexion/rotation trunk
• Trapezius: extension and hyperextension of head
• Erector spinae: extension/lateral flexion/rotation
spine
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Upper Limb Muscles
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Upper Limp Muscles
• Deltoid: abduction, flexion, extension, and rotation
of arm
• Latissimus dorsi: extension, adduction, and medial
rotation of arm
• Biceps brachii: flexion of forearm
• Brachialis: flexion of forearm
• Brachioradialis: flexion of forearm
• Triceps brachii: extension of forearm
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Lower Limb Muscles
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Lower Limb Muscles
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Gluteus maximus: extension and lateral rotation of leg
Gluteus medius: abduction and medial rotation of leg
Iliopsoas: flexion of leg at hip
Quadriceps: extension of leg at knee
Hamstrings: flexion of leg at knee
Sartorius: assists with flexion, abduction, and lateral
rotation of thigh
• Gastrocnemius: plantar flexion, flexion of leg at knee
• Soleus: plantar flexion
• Tibialis anterior: dorsiflexion and inversion of foot
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Review and Assessment
Match these words with 1–4 below: head, trunk,
upper limb, lower limb.
1. temporalis
2. brachioradialis
3. external oblique
4. biceps femoris
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Chapter 5: The Muscular System
Lesson 5.4
Common Injuries and
Disorders of Muscles
Muscle Injuries
• strain–overstretched muscle
– grade I, II, III
• contusion–bruised muscle
– myositis ossificans
• cramps–spasming muscle
• delayed onset muscle soreness–tear
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Tendon Injuries
• tendinitis–
inflamed tendon
• tendinosis–
degeneration of
a tendon
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Joint Injuries
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rotational injury at shoulder
overuse of elbow
shin splints
whiplash
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Muscle Disorders
• muscular dystrophy
• hernia
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Review and Assessment
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.
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