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Chapter 9
THE MUSCULAR SYSTEM
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to a publicly accessible website, in whole or in part.
Introduction
• Skeletal muscles: movement in
environment
• Smooth muscles: intestines, ureters, veins
and arteries
• Cardiac muscle: pumps blood through heart
and blood vessels
• 40% - 50% of body weight
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
THE TYPES OF MUSCLE
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The Types of Muscle (cont’d.)
• Skeletal: voluntary, striated, multinucleated
• Smooth: involuntary, nonstriated and
uninucleated
• Cardiac: involuntary, striated and
uninucleated
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to a publicly accessible website, in whole or in part.
THE ANATOMY OF SKELETAL OR STRIATED
MUSCLE
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The Anatomy of Skeletal or
Striated Muscle (cont’d.)
• Skeletal muscle cell surrounded by
sarcolemma
• Fasciculi: bundles of fascicles
• Fascicles: individual bundles of muscle
fibers
• Perimysium: surrounds each fascicle
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The Anatomy of Skeletal or
Striated Muscle (cont’d.)
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Epimysium: covers the perimysium
Fascia: covers the epimysium
Myosin: A bands
Actin: I bands
Z lines
H zone
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The Anatomy of Skeletal or
Striated Muscle (cont’d.)
• Sarcomere: between two adjacent Z lines
– Actual contraction process occurs here
• Sarcotubular system
– T system and sarcoplasmic reticulum
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to a publicly accessible website, in whole or in part.
THE PHYSIOLOGY OF MUSCLE CONTRACTION
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Introduction
• Motor unit: all muscle cells innervated by
one motor neuron
• Muscle cell properties
– Excitability
– Conductivity
– Contractility
– Elasticity
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Neuroelectrical Factors
• Na+ higher concentration outside muscle
cell
• K+ higher concentration inside muscle cell
• Resting potential: charge outside positive
and inside negative
• Electrical potential: rush of Na+ inside cell
• K+ moves outside cell attempting to balance
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Neuroelectrical Factors (cont’d.)
• Action potential
– Calcium released
– Troponin and tropomyosin action inhibited
– Activated myosin links to actin filaments
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Chemical Interactions
• Myosin heads contain ATP
• ATP releases energy upon myosin/action
link
• Energy released used to pull action
• Sodium: potassium pump pumps out sodium
• Resting potential restored
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to a publicly accessible website, in whole or in part.
Energy Sources
• ATP: energy source for muscle contraction
• ATP production
– Glycolysis
– Krebs citric acid cycle
– Electron transport
• Alternate sources: fatty acids and
phosphocreatine
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to a publicly accessible website, in whole or in part.
THE MUSCLE TWITCH
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The Muscle Twitch (cont’d.)
• Stimulus > latent period > contraction >
relaxation
• Contraction strength depends on
– Strength, speed and duration of stimulus
– Weight of load
– Temperature
• All-or-none law
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
MUSCLE TONE
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Muscle Tone (cont’d.)
• State of partial contraction throughout
whole muscle
• Maintains pressure on abdominal contents
• Helps maintain blood pressure
• Aids digestion
• Types
– Isotonic, isometric
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to a publicly accessible website, in whole or in part.
THE ANATOMY OF SMOOTH MUSCLE
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The Anatomy of Smooth Muscle
(cont’d.)
• Found in hollow structures
• Involuntary, uninucleated, nonstriated
• Arrangement (two layers)
– Longitudinal (outer)
– Circular (inner)
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to a publicly accessible website, in whole or in part.
THE ANATOMY OF CARDIAC MUSCLE
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The Anatomy of Cardiac Muscle
(cont’d.)
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Autonomic nervous system control
Involuntary, uninucleated, striated
Intercalated disks: coordinate contraction
Cardiac muscles: contract, relax and
contract 75 times/minute
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
THE NAMING AND ACTIONS OF SKELETAL
MUSCLES
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to a publicly accessible website, in whole or in part.
The Naming and Actions of
Skeletal Muscles (cont’d.)
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Action
Shape
Origin and insertion
Location
Direction of fibers
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
The Naming and Actions of
Skeletal Muscles (cont’d.)
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Origin: more fixed attachment of muscle
Insertion: movable attachment of muscle
Tendons: attach muscle to bone
Aponeurosis: wide flat tendon
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
The Naming and Actions of
Skeletal Muscles (cont’d.)
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Flexors: bend limb at a joint
Extensor: straighten limb at a joint
Abductors: move limb away from midline
Adductors: bring limb toward midline
Rotators: revolve limb around axis
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
The Naming and Actions of
Skeletal Muscles (cont’d.)
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Dorsiflexors: raise the foot
Plantar flexors: lower the foot
Supinators: turn palm upward
Pronators: turn palm downward
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The Naming and Actions of
Skeletal Muscles (cont’d.)
• Levators: raise a part of the body
• Depressors: lower a part of the body
• Prime movers or agonists: bring about an
action
• Antagonists: oppose agonists
• Synergists: assist prime movers
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to a publicly accessible website, in whole or in part.
THE FUNCTION AND LOCATION OF SELECTED
SKELETAL MUSCLES
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Superficial Muscles
• Superficial muscles
of the body,
anterior view
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
Superficial Muscles (cont’d.)
• Superficial muscles
of the body,
posterior view
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to a publicly accessible website, in whole or in part.
Muscles of Facial Expression
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Occipitalis
Frontalis
Zygomaticus
Levator labii superioris
Orbicularis oris and buccinator
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to a publicly accessible website, in whole or in part.
Muscles of Facial Expression
(cont’d.)
• Muscles of the head
and neck, anterior
view
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to a publicly accessible website, in whole or in part.
Muscles of Facial Expression
(cont’d.)
• Muscles of the
head and neck,
lateral view
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to a publicly accessible website, in whole or in part.
Muscles of Mastication
• Masseter
• Temporalis
• Pterygoid
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to a publicly accessible website, in whole or in part.
Muscles of the Eye
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Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Superior and inferior oblique
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Muscles Moving the Head
• Sternocleidomastoid
– Contraction of both causes flexion of neck
– Contraction of one causes rotation to left or
right
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to a publicly accessible website, in whole or in part.
Muscles Moving the Shoulder
Girdle
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Levator scapulae
Rhomboids
Pectoralis minor
Trapezius
Serratus anterior
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to a publicly accessible website, in whole or in part.
Muscles Moving the Humerus
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Pectoralis major
Latissimus dorsi
Teres minor
Deltoid
Supraspinatus
Infraspinatus
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to a publicly accessible website, in whole or in part.
Muscles Moving the Elbow
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Brachialis
Biceps brachii
Brachioradialis
Triceps brachii
Anconeus
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to a publicly accessible website, in whole or in part.
Muscles Moving the Wrist
• Flexor carpi
• Extensor carpi
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to a publicly accessible website, in whole or in part.
Muscles Moving the Hand
• Supinator
• Pronator teres
• Pronator quadratus
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to a publicly accessible website, in whole or in part.
Muscles Moving the Thumb
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Flexor pollicis
Extensor pollicis
Adductor pollicis
Abductor pollicis
Opponens pollicis
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to a publicly accessible website, in whole or in part.
Muscles Moving the Fingers
• Flexor digitorum
• Extensor digitorum
• Interossei
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to a publicly accessible website, in whole or in part.
Muscles of the Abdominal Wall
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External oblique
Internal oblique
Transversus abdominis
Rectus abdominis
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to a publicly accessible website, in whole or in part.
Muscles of the Abdominal Wall
(cont’d.)
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to a publicly accessible website, in whole or in part.
Muscles of Respiration or
Breathing
• Diaphragm
– Main muscle
• External and internal intercostals
– Expand the ribs
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to a publicly accessible website, in whole or in part.
Muscles Moving the Femur
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Psoas
Iliacus
Gluteus maximus
Gluteus medius
Gluteus minimus
Tensor fascia lata
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to a publicly accessible website, in whole or in part.
Muscles Moving the Knee Joint
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Biceps femoris
Semitendinosus
Semimembranosus
Popliteus
Gracilis
Sartorius
Quadriceps femoris
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to a publicly accessible website, in whole or in part.
Muscles Moving the Foot
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Gastrocnemius
Tibialis posterior
Soleus
Peroneus longus
Plantaris
Tibialis anterior
Peroneus tertius
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to a publicly accessible website, in whole or in part.
Muscles Moving the Toes
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Flexor hallucis
Extensor hallucis
Flexor digitorum
Extensor digitorum
Abductor hallucis
Abductor digiti minimi
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to a publicly accessible website, in whole or in part.
Animation – Accessory Muscle
Use
• The following animation illustrates how the accessory
muscles assist with the breathing process
Click Here to Play Accessory Muscle Use Animation
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
Summary
• Described the gross and microscopic
anatomy of skeletal muscle
• Contrasted skeletal, smooth and cardiac
muscle anatomy
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.
Summary (cont’d.)
• Described muscle contraction and the role
of neuroelectrical and chemical factors and
energy sources
• Named major muscles of the body
© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted
to a publicly accessible website, in whole or in part.