Podcast Beta
Questions and Answers
Which of the following is NOT one of the four characteristics of muscle tissue?
What is the primary function of muscle tissue related to temperature?
Which layer of connective tissue surrounds the entire skeletal muscle?
What structure is found at the site of chemical communication between a neuron and a muscle fiber?
Signup and view all the answers
Which of the following is a thick filament found within myofibrils?
Signup and view all the answers
What is the main characteristic of red muscle fibers?
Signup and view all the answers
What distinguishes Type 2A muscle fibers from Type 2 fibers?
Signup and view all the answers
What is the main role of satellite cells in muscle tissue?
Signup and view all the answers
What do Z discs define in a sarcomere?
Signup and view all the answers
What is the significance of the synaptic cleft in muscle contraction?
Signup and view all the answers
Which type of muscle contraction is characterized by brief, involuntary twitches not visible under the skin?
Signup and view all the answers
Which component is responsible for holding calcium ions in muscle cells?
Signup and view all the answers
Which organization pattern of muscle fibers is characterized by fibers running parallel to the muscle's longitudinal axis?
Signup and view all the answers
What happens when a threshold stimulus is reached according to the all-or-none principle?
Signup and view all the answers
What type of muscle fibers produce ATP anaerobically and are characterized as fast-twitch?
Signup and view all the answers
Which type of atrophy occurs due to loss of nerve supply?
Signup and view all the answers
What is the primary action of synergist muscles?
Signup and view all the answers
Which muscle shape is represented by the term 'deltoid'?
Signup and view all the answers
Which of the following describes the function of fixators?
Signup and view all the answers
Which prefix indicates a muscle with two tendons of origin?
Signup and view all the answers
What distinguishes intrinsic muscles from extrinsic muscles?
Signup and view all the answers
Which term describes skeletal muscles whose actions oppose the actions of agonists?
Signup and view all the answers
What term refers to muscle fibers running at an angle to the long axis of the body?
Signup and view all the answers
Which muscle group does 'maximus' denote?
Signup and view all the answers
Study Notes
Myology
- Study of muscles.
- Four key characteristics: excitability, contractibility, extensibility, and elasticity.
Main Muscle Functions
- Movement: Muscles contract to produce motion.
- Support: Muscles help maintain posture and stability.
- Body temperature maintenance: Muscle contraction generates heat.
- Guarding orifices: Muscles control openings in the body.
Muscle Types
- Smooth: Involuntary muscle found in internal organs.
- Cardiac: Involuntary muscle found in the heart.
- Skeletal: Voluntary muscle attached to bones, responsible for movement.
Gross Anatomy of Skeletal Muscle
- Three layers of connective tissue:
- Epimysium: Surrounds the entire muscle.
- Perimysium: Divides muscle into compartments (fascicles).
- Endomysium: Surrounds individual muscle fibers.
- Satellite cells: Located between the endomysium and muscle fibers, responsible for muscle repair.
- Tendon: Connective tissue that attaches muscle to bone.
- Neuromuscular junction: Site where a motor neuron communicates with a muscle fiber.
Microanatomy of Muscle Fibers
- Sarcolemma: Plasma membrane of muscle fiber.
- Sarcoplasm: Cytoplasm of muscle fiber.
- Muscle fibers: Long, multinucleated cells formed by fusion of myoblasts.
- Transverse tubules (T-tubules): Invaginations of the sarcolemma that conduct electrical impulses.
- Myofibrils: Contractile units within muscle fibers, composed of myofilaments.
- Mitochondria: Abundant in muscle fibers to provide energy.
- Glycogen: Stored energy source in muscle fibers.
Structure of Myofibrils
- Composed of thin filaments and thick filaments.
- Thin filaments: Primarily made of actin.
- Thick filaments: Primarily made of myosin.
- Troponin and Tropomyosin: Regulatory proteins associated with actin.
- Titin: Large protein that helps maintain structure and elasticity.
Sarcomere: The Functional Unit of Muscle
- Z-disks/lines: Separate adjacent sarcomeres.
- A-band: Dark band, where thick and thin filaments overlap.
- M-line: Center of the A-band, where thick filaments connect.
- H-zone: Light zone in the center of the A-band, containing only thick filaments.
- I-band: Light band, containing only thin filaments.
Motor Neurons and Muscle Contraction
- Motor neurons: Stimulate muscle fibers.
- Synaptic vesicles: Contain acetylcholine, a neurotransmitter.
- Synaptic cleft: Space between the axon terminal and sarcolemma.
All-or-None Principle
- Muscle fibers within a motor unit contract maximally or not at all, depending on the strength of the stimulus.
Muscle Atrophy and Hypertrophy
- Disuse atrophy: Muscle wasting due to lack of use.
- Denervation atrophy: Muscle wasting due to nerve damage.
- Hypertrophy: Muscle growth due to increased workload.
Types of Skeletal Muscle Fibers
- Red muscle fibers (Type I): Slow-twitch, oxidative, fatigue-resistant. High myoglobin content, rich in mitochondria and blood supply.
- White muscle fibers (Type II): Fast-twitch, glycolytic, fatigable. Low myoglobin content, fewer mitochondria and blood supply.
- Type IIA fibers (Intermediate): Fast-twitch, oxidative and fatigue-resistant.
Abnormal Muscle Contractions
- Spasm: Involuntary contraction of a large group of muscles.
- Tremor: Rhythmic, involuntary contractions of opposing muscle groups.
- Fasciculation: Brief, involuntary twitch of a muscle visible under the skin.
- Fibrillation: Brief, involuntary twitch of a muscle not visible under the skin.
Organization of Muscle Fibers
- Four patterns of fascicle arrangement:
- Parallel: Fibers run parallel to the long axis of the muscle.
- Convergent: Fibers converge from a broad origin to a single insertion.
-
Pennate: One or more tendons run through the muscle.
- Unipennate: Muscle fibers on one side of the tendon.
- Bipennate: Muscle fibers on both sides of the tendon.
- Circular or sphincter: Concentrically arranged around an opening.
Muscle Attachments, Actions, and Naming
- Origin: Fixed point of attachment.
- Insertion: Movable point of attachment.
- Action: Movement produced by muscle contraction.
Muscle Action Types
- Prime movers (agonists): Muscles primarily responsible for a specific movement.
- Synergists: Muscles that assist prime movers.
- Antagonists: Muscles that oppose the action of prime movers.
- Fixators: Muscles that stabilize the origin of prime movers.
Skeletal Muscle Naming Conventions
-
Directional:
- Rectus: Straight fibers.
- Transversus: Fibers run across.
- Obliques: Fibers run at an angle.
-
Unusual structure features:
- Biceps: Two tendons of origin.
- Triceps: Three tendons of origin.
- Quadriceps: Four tendons of origin.
-
Shape:
- Trapezius: Trapezoid.
- Deltoid: Triangular.
- Rhomboideus: Rhomboid.
- Orbicularis: Circular.
- Longus: Long.
- Longissimus: Longest.
- Teres: Long and round.
- Brevis: Short.
- Magnus: Big.
- Major: Bigger.
- Maximus: Biggest.
- Minor: Small.
- Minimus: Smallest.
-
Location
- Externus or superficial: Visible at body surface.
- Internus or profundus: Internal.
- Extrinsic: Muscles that position or stabilize an organ.
- Intrinsic: Muscles that operate within an organ.
-
Origin and Insertion:
- Genioglossus: Originates at the chin (genio) and inserts on the tongue (glossus).
-
Function:
- Flexor: Muscle that decreases joint angle.
- Extensor: Muscle that increases joint angle.
- Retractor: Muscle that draws a structure backwards.
-
General:
- Most skeletal muscles have "muscle" in their names, except for the platysma and diaphragm.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Learn about myology, the study of muscles, including their key characteristics and functions. This quiz covers the types of muscles, their anatomical structure, and the important roles they play in the body. Test your knowledge on smooth, cardiac, and skeletal muscles, along with their connective tissues.
