CHAPTER 7 STUDY
GUIDE
MUSCULAR SYSTEM
Anatomy Bowl
Prep
By: Amanda
Morden
THREE MAJOR T YPES OF MUSCLE TISSUE
( U N D E R S TA N D T H E D I F F E R E N C E S )
1. Skeletal muscle
-”striated muscle”
-”voluntary muscle”
2. Cardiac muscle
-”striated muscle”
-”involuntary muscle”
3. Smooth muscle
-”voluntary muscle”
-”visceral muscle”
For each, know where it is located, the physical description, and
what it does
 Skeletal muscle:
 Is in our biceps, triceps, postural muscles, etc
 Smooth muscle:
 Is found along our digestive tract: used to move food along
 Cardiac muscle:
 Is found in the heart
STRUCTURE OF SKELETAL MUSCLE
 Origin
 The stationary attachment to bone
 Insertion
 The more movable attachment site to bone
 Tendons
 Anchor muscles firmly to bones
 Made of dense fibrous connective tissue in the shape of heavy cords
 Bursae
 Lie in between some tendons and bones beneath them
 Synovial membrane
 Secretes a slippery lubricating fluid that fills the bursa
 Tendon sheaths
 Enclose some tendons
MICROSCOPIC STRUCTURE OF SKELETAL
MUSCLE
 Muscle fibers
 Specialized contractile cells that are grouped together and
arranged in a highly organized way
 Thin and thick myofilaments
 Thick filaments are composed of myosin
 Thin filaments composed of actin
 Actin
 Thin filaments
 Myosin
 Thick filaments
 Sarcomere
 The basic functional or contractile unit of skeletal muscle
MUSCLE STIMULUS
 Understand what a motor unit is and how it works
Define:
 Neuromuscular junction
 Specialized point of contact between a nerve ending and the muscle fiber it
innervates
 Motor neuron
 a specialized nerve that transmits an impulse to a muscle
 Know how the process of muscle stimulus works
 When does a muscle fiber fire?
 When stimulated a muscle fiber will fire when it has reached its threshold
 When does it not?
 If the stimulus is not strong enough the muscle will not fire
Understand and define:
 Threshold stimulus
 Minimal level of stimulation needed to make a muscle contract
 “All or none” muscle response
 Muscles will not partially contract. It will contract or remain the same
T YPES OF SKELETAL MUSCLE
CONTRACTION
 Know the dif ference between:
1. A twitch contraction vs. a tetanic contraction
2. An isotonic contraction vs. an isometric contraction
 Twitch contraction
 Is laboratory
 Does not play a significant role in normal muscular activity
 Tetanic
 Are sustained and steady contractions caused by a series of stimuli
bombarding the muscle
EXERCISE EFFECTS
 What happens when you don’t exercise?
Know and define:
 Disuse atrophy
 Atrophy is when the muscle fibers weak due to lack of stimulation
 What happens when you do exercise?
Know and define:
 Hypertrophy
 Hypertrophy is the increased size of a muscle due to increase of cells
 What are dif ferent types of exercise?
Know and define:
 Strength training
 Exercise involving the contraction of muscle against heavy resistance
 Endurance training
 Increases a muscles ability to sustain moderate exercise over a long
period of time
 is also called “Aerobic training”
 Allows for more efficient deliver of oxygen to muscles
SKELETAL MUSCLE GROUPS
Know the muscles of each group and what each
muscle does
 Muscles of the Head and Neck
 Facial muscles
 Orbicularis oculi
 Orbicularis oris
 Zygomaticus
 Muscles of Mastication
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Masseter
Temporal
Sternocleidomastoid
trapezius
 Muscles that move the Upper Extremities
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Pectoralis major- flexes upper arm
Latissimus dorsi- extends upper arm
Deltoid- abducts upper arm
Biceps brachii-flexes forearm
Triceps brachii- extends forearm
 Muscles of the Trunk
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Rectus abdominis
External oblique
Internal oblique
Transversus abdominis
 Muscles that move the Lower Extremities
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Iliopsoas-flexes hip
Gluteus maximus- extends thigh
Adductor magnus- adducts thighs
Hamstrings- flex lower leg
Quadriceps- extends lower leg
MOVEMENTS PRODUCED BY SKELETAL
MUSCLE CONTRACTIONS
 Flexion
 Movement that decreases the angle between two bones at their joint: bending
 Extension
 Movement that increases the angle between two bones
 Abduction
 Movement of a part away from the midline of the body
 Adduction
 Movement of a part towards the midline of the body
 Rotation
 Movement around a longitudinal axis
 Supination and pronation
 Hand positions that result from rotation of the forearm;
 Supination results in palms facing up
 Pronation results in palms facing down
 Dor siflexion and plantar flexion
 Foot movements;
 Dorsiflexion results in elevation of dorsum or top of foot
 During plantar flexion- the bottom of the foot is directed downward