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The Muscular System: Part A
10 The Muscular System: Part A
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WARM UP QUESTION Muscle tone is ________.
the ability of a muscle to efficiently cause skeletal movements the feeling of well-being following exercise a state of sustained partial contraction the condition of athletes after intensive training
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WARM UP QUESTION Muscle tissue has all of the following properties except ________. secretion contractility extensibility excitability
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WARM UP QUESTION After nervous stimulation stops, ACh in the synaptic cleft is prevented from continuing stimulation of contraction by ________. calcium ions returning to the terminal cisternae the tropomyosin blocking the myosin once full contraction is achieved acetylcholinesterase destroying the ACh the action potential stopped going down the overloaded T tubules
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WARM UP QUESTION The functional role of the T tubules is to ________.
stabilize the G and F actin enhance cellular communication during contraction hold cross bridges in place in a resting muscle synthesize ATP to provide energy for muscle contraction
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WARM UP QUESTION Which of the following surrounds the individual muscle cell? perimysium endomysium epimysium fascicle
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WARM UP QUESTION An elaborate network of membranes in skeletal muscle cells that functions in calcium storage is the ________. sarcoplasmic reticulum mitochondria intermediate filament network myofibrillar network
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WARM UP QUESTION Calcium ions bind to the ________ molecule in skeletal muscle cells. actin tropomyosin troponin myosin
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WARM UP QUESTION The strongest muscle contractions are normally achieved by ________. increasing stimulus above the threshold increasing stimulus above the treppe stimulus increasing the stimulation up to the maximal stimulus recruiting small and medium muscle fibers
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WARM UP QUESTION Which cells have the greatest ability to regenerate?
skeletal cardiac smooth no muscle can regenerate
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WARM UP QUESTION Which of the following statements is true regarding the total number of skeletal muscles in the human body? There are approximately the same number of muscles as bones: 206. There are approximately 350 muscles in the body. There are over 600 muscles in the body. If one considers the very tiny, insignificant muscles, there are over 1000 muscles in the body.
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Skeletal Muscles: Functional Groups
Prime movers Provide the major force for producing a specific movement Antagonists Oppose or reverse a particular movement
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Skeletal Muscles: Functional Groups
Synergists Add force to a movement Reduce undesirable or unnecessary movement Fixators Synergists that immobilize a bone or muscle’s origin
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FALSE – They are called FIXATORS
TRUE OR FALSE Muscles that help to maintain posture are often called synergists. FALSE – They are called FIXATORS
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QUESTION A muscle that provides the major force for producing a specific movement is called ________. a synergist an agonist an antagonist a fixator
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QUESTION A muscle group that works with and assists the action of a prime mover is a(n) ________. antagonist fixator synergist protagonist
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Naming Skeletal Muscles
How are the skeletal muscles named? L S D # of A
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Naming Skeletal Muscles
How are the skeletal muscles named? Location Shape Size Direction of fibers Number of origins Attachments Action
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Naming Skeletal Muscles
Location—bone or body region associated with the muscle Shape—e.g., deltoid muscle (deltoid = triangle) Relative size—e.g., maximus (largest), minimus (smallest), longus (long) Direction of fibers or fascicles—e.g., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis)
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Naming Skeletal Muscles
Number of origins—e.g., biceps (2 origins) and triceps (3 origins) Location of attachments—named according to point of origin or insertion Action—e.g., flexor or extensor, muscles that flex or extend, respectively
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What primarily determines the power of a muscle?
QUESTION What primarily determines the power of a muscle? the length the shape the number of neurons innervating it the total number of muscle cells available for contraction
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10 Arrangements
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TRUE OR FALSE Although all skeletal muscles have different shapes, the fascicle arrangement of each muscle is exactly the same. FALSE – Of course not!
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Muscle Mechanics: Arrangement of Fascicles
Circular Fascicles arranged in concentric rings (e.g., orbicularis oris) Convergent Fascicles converge toward a single tendon insertion (e.g., pectoralis major)
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Orbicularis oris ________.
QUESTION Orbicularis oris ________. closes, purses, and protrudes the lips pulls the lower lip down and back draws the eyebrows together allows blinking, squinting, and various other protective mechanisms for the eye
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Muscle Mechanics: Arrangement of Fascicles
Parallel Fascicles parallel to the long axis of a straplike muscle (e.g., sartorius) Fusiform Spindle-shaped muscles with parallel fibers (e.g., biceps brachii)
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Muscle Mechanics: Arrangement of Fascicles
Pennate Short fascicles attach obliquely to a central tendon running the length of the muscle (e.g., rectus femoris)
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TRUE OR FALSE The arrangement of a muscle's fascicles determines its range of motion and power. TRUE!
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TRUE OR FALSE Muscle power does not depend on the direction of the fascicles. TRUE!
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With regard to muscle fiber arrangement in a pennate muscle ________.
QUESTION With regard to muscle fiber arrangement in a pennate muscle ________. the fascicles are short and attach obliquely to a central tendon that runs the length of a muscle the fascicular pattern is circular the fascicles form a triangle the fascicles are in a fusiform arrangement
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QUESTION The muscles that are found at openings of the body are collectively called ________. convergent muscles circular muscles parallel muscles divergent muscles
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(a) (g) (b) (f) Circular (orbicularis oris) (b) Convergent
(pectoralis major) (c) (e) (c) Parallel (sartorius) (d) Unipennate (extensor digitorum longus) (d) (e) Bipennate (rectus femoris) (f) Fusiform (biceps brachii) (g) Multipennate (deltoid) Figure 10.1
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Major Skeletal Muscles of the Body
Grouped by function and location Information for each muscle Name and description—note information in the name Origin and insertion—there is usually a joint between the origin and the insertion Action—insertion moves toward origin; best learned by acting out muscle movement on one’s own body Innervation—name of major nerve that supplies the muscle
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When the term biceps, triceps, or quadriceps forms part of a muscle's name, you can assume that ________. the muscle has two, three, or four origins, respectively the muscle is able to change direction twice, three times, or four times faster than other muscles, respectively the muscle has two, three, or four functions, respectively the muscle has two, three, or four insertions, respectively
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QUESTION The names of muscles often indicate the action of the muscle. When the term levator is part of the descriptive term for a muscleʹs action, this means that ________. the muscle flexes and rotates a region the muscle is a fixator and stabilizes a bone or joint the muscle elevates and/or adducts a region the muscle functions as a synergist
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The suprahyoid muscles ________.
QUESTION The suprahyoid muscles ________. depress the larynx and hyoid bone if the mandible is fixed are a group of muscles that lie superior to the hyoid bone and help form the floor of the oral cavity Move the pharynx superiorly during swallowing are often called strap muscles
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Epicranius, frontal belly Orbicularis oculi Masseter Zygomaticus
Head Facial Temporalis Epicranius, frontal belly Orbicularis oculi Masseter Zygomaticus Shoulder Orbicularis oris Trapezius Neck Deltoid Sternohyoid Arm Platysma Triceps brachii Sternocleidomastoid Biceps brachii Thorax Brachialis Forearm Pectoralis minor Serratus anterior Pronator teres Pectoralis major Brachioradialis Intercostals Flexor carpi radialis Palmaris longus Abdomen Pelvis/thigh Rectus abdominis Iliopsoas Internal oblique Pectineus Transversus abdominis Thigh External oblique Rectus femoris Thigh Vastus lateralis Tensor fasciae latae Vastus medialis Sartorius Adductor longus Leg Gracilis Fibularis longus Leg Extensor digitorum longus Gastrocnemius Tibialis anterior Soleus Figure 10.4
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Epicranius, occipital belly Sternocleidomastoid Arm Trapezius
Neck Epicranius, occipital belly Sternocleidomastoid Arm Trapezius Triceps brachii Shoulder Brachialis Deltoid Forearm Infraspinatus Brachioradialis Teres major Extensor carpi radialis longus Rhomboid major Latissimus dorsi Flexor carpi ulnaris Hip Extensor carpi ulnaris Gluteus medius Gluteus maximus Extensor digitorum Iliotibial tract Thigh Adductor magnus Hamstrings: Leg Biceps femoris Gastrocnemius Semitendinosus Soleus Semimembranosus Fibularis longus Calcaneal (Achilles) tendon Figure 10.5
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A muscle located on the dorsal side of the body is the ________.
QUESTION A muscle located on the dorsal side of the body is the ________. pectoralis minor rectus femoris rectus abdominis infraspinatus
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Which of the following muscles does not act in plantar flexion?
QUESTION Which of the following muscles does not act in plantar flexion? popliteus tibialis posterior flexor digitorum longus gastrocnemius and soleus
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