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Questions and Answers
What is the structural unit of muscle?
What is the structural unit of muscle?
- Muscle Fiber (correct)
- Fascicle
- Epimysium
- Tendon
Which connective tissue layer ensheathes the entire muscle?
Which connective tissue layer ensheathes the entire muscle?
- Endomysium
- Perimysium
- Fascia
- Epimysium (correct)
What is an intermediate tendon?
What is an intermediate tendon?
- A segment of the muscle that lacks both origin and insertion (correct)
- A structure that connects muscle to cartilage
- A tendon that connects muscle to skin
- A tendon that has no attachment to bone
Which of the following structures protects muscle cells and provides passage for vessels and nerves?
Which of the following structures protects muscle cells and provides passage for vessels and nerves?
Which of the following best describes the 'belly' of a muscle?
Which of the following best describes the 'belly' of a muscle?
Which layer of connective tissue surrounds each muscle fiber?
Which layer of connective tissue surrounds each muscle fiber?
What is the process by which muscle fibers are innervated?
What is the process by which muscle fibers are innervated?
Which of the following muscle attachments is characterized by direct attachment to the skin or superficial fascia?
Which of the following muscle attachments is characterized by direct attachment to the skin or superficial fascia?
What is the primary function of skeletal muscles?
What is the primary function of skeletal muscles?
Which characteristic describes irritability in muscle tissue?
Which characteristic describes irritability in muscle tissue?
What type of muscle is characterized by being uni-nucleate and non-striated?
What type of muscle is characterized by being uni-nucleate and non-striated?
Which component distinguishes cardiac muscle from the other types?
Which component distinguishes cardiac muscle from the other types?
How much of the body's weight do skeletal muscles constitute?
How much of the body's weight do skeletal muscles constitute?
What type of control do skeletal muscles operate under?
What type of control do skeletal muscles operate under?
What characteristic is NOT associated with smooth muscles?
What characteristic is NOT associated with smooth muscles?
Which of the following describes the extensibility of muscle tissue?
Which of the following describes the extensibility of muscle tissue?
Which type of muscle fiber arrangement involves fibers that run parallel to the line of pull?
Which type of muscle fiber arrangement involves fibers that run parallel to the line of pull?
What is the function of synergist muscles?
What is the function of synergist muscles?
What characterizes unipennate muscle fibers?
What characterizes unipennate muscle fibers?
What are the primary components of a motor unit?
What are the primary components of a motor unit?
Which accessory structure of skeletal muscle serves to reduce friction on tendons?
Which accessory structure of skeletal muscle serves to reduce friction on tendons?
How do antagonist muscles function in relation to agonist muscles?
How do antagonist muscles function in relation to agonist muscles?
Which muscle fiber arrangement is characterized by muscle fibers attached to multiple fibrous bands?
Which muscle fiber arrangement is characterized by muscle fibers attached to multiple fibrous bands?
What is typically found in the belly of skeletal muscle regarding blood supply?
What is typically found in the belly of skeletal muscle regarding blood supply?
Flashcards
Parallel muscle fibers
Parallel muscle fibers
Muscle fibers run parallel to the line of muscle pull
Fusiform muscle fibers
Fusiform muscle fibers
Muscle fibers are thick in the middle and tapered at the ends, similar to a spindle.
Oblique muscle fibers (Pennate)
Oblique muscle fibers (Pennate)
Muscle fibers attach to a tendon at an oblique angle, like feathers.
Prime Mover (Agonist)
Prime Mover (Agonist)
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Antagonist muscle
Antagonist muscle
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Synergist muscle
Synergist muscle
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Sesamoid bone
Sesamoid bone
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Circular muscle fibers
Circular muscle fibers
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Skeletal Muscle Function
Skeletal Muscle Function
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Muscle Fiber
Muscle Fiber
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Smooth Muscle Location
Smooth Muscle Location
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Fascicle
Fascicle
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Epimysium
Epimysium
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Cardiac Muscle Structure
Cardiac Muscle Structure
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Perimysium
Perimysium
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Smooth Muscle Control
Smooth Muscle Control
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Endomysium
Endomysium
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Muscle Excitability
Muscle Excitability
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Muscle Origin
Muscle Origin
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Muscle Contractility
Muscle Contractility
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Muscle Insertion
Muscle Insertion
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Muscle Extensibility
Muscle Extensibility
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Muscle Elasticity
Muscle Elasticity
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Muscle Belly
Muscle Belly
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Study Notes
Myology
- Myology is the science that deals with muscles.
- Skeletal muscles are the active component of the locomotor system.
- Smooth muscles move the visceral organs.
- Cardiac muscle contracts the heart.
Muscle Characteristics
- Irritability/Excitability: muscles respond to chemical, electrical, or mechanical stimuli.
- Contractility: muscles can shorten.
- Extensibility: muscles can stretch.
- Elasticity: muscles return to their original length.
Smooth Muscle
- Structure: spindle-shaped, single-nucleus, non-striated.
- Location: walls of visceral organs.
- Control: involuntary, controlled by autonomic nervous system or endocrine system (myoepithelial cells).
- Function: involuntary contractions to move materials through organs.
Cardiac Muscle
- Structure: cylindrical, mostly single-nucleus, striated, branching, forming a network (syncytium). Connected via intercalated disks.
- Location: heart wall.
- Control: involuntary, with an intrinsic conduction system.
Skeletal Muscle
- Structure: elongated, multinucleated, striated. Divided into bundles/fascicles. Each fascicle is comprised of numerous muscle fibers.
- Percentage of body weight: 40-45%.
- Location: throughout the body, forming the active part of the locomotor system.
- Control: voluntary.
Skeletal Muscle Function
- Voluntary body movements.
- Maintaining posture.
- Stabilizing joints.
- Generating heat.
- Guarding body openings and orifices.
Skeletal Muscle Architecture
- Each muscle is a group of bundles called fascicles.
- Each fascicle is a group of muscle fibers (cells).
- Muscle fiber is the structural unit of muscle.
Skeletal Muscle Architecture Components
- Epimysium: connective tissue sheath surrounding the entire muscle.
- Perimysium: connective tissue sheath surrounding fascicles.
- Endomysium: connective tissue sheath surrounding individual muscle fibers.
- Tendon and Aponeurosis: connect muscle to bone.
Microscopic Muscle Structure
- Myofibril: contractile thread within muscle fiber.
- Sarcomere: functional unit of myofibril, bounded by Z-lines.
- Myofilaments: filaments within sarcomere (actin & myosin).
Gross Anatomy of Skeletal Muscle
- Origin: usually the proximal, less movable attachment of the muscle.
- Insertion: usually the distal, more movable attachment of the muscle.
- Belly: the main part of the muscle between the origin and insertion.
Skeletal Muscle Attachments
- Bone
- Cartilage
- Deep fascia
- Skin and superficial fascia
- Intermediate tendon
- No attachment (e.g., orbicularis oris)
Skeletal Muscle Fiber Arrangements
- Parallel fibers (e.g., strap muscles, quadratus muscles).
- Fusiform fibers (bundles running nearly parallel).
- Oblique fibers (pennate): unipennate (one side), bipennate (both sides), multipennate (multiple attachments).
- Circular fibers (e.g., orbicularis oris).
- Convergent fibers (e.g., pectoralis major).
Functional Types of Muscles
- Prime mover (agonist): muscle primarily responsible for producing a movement.
- Antagonist: muscles that oppose the action of the agonist.
- Synergist: muscles that assist the prime mover.
- Fixator/stabilizer: muscles that stabilize a joint to allow movement of another part of the body.
Blood and Nerve Supply
- Vessels and nerves pass through connective tissue sheaths.
- Muscle belly is highly vascular.
- One neuron can innervate multiple muscle fibers. (Motor units)
- Each motor unit contracts together.
Neuromuscular Junction
- Motor neurons connect to muscle fibers at the neuromuscular junction.
- Neurotransmitters (e.g., acetylcholine) are released to initiate muscle contraction.
Accessory Structures of Skeletal Muscle
- Sesamoid bones: embedded within tendons (e.g., patella).
- Fascia: connective tissue sheath covering the body and individual muscles.
- Synovial sacs: fluid-filled sacs between structures, decreasing friction.
- Tendon synovial sheath: double-layered sheath surrounding tendons reducing friction.
Retinaculum
- Transverse band of deep fascia surrounding joints (carpal, tarsal).
- Holds tendons and ligaments in place.
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