Muscular System Summary
Muscle Organization and Function
Affects power, range, and speed of muscle movement.
Muscle fibers organized in bundles (fascicles); can be arranged in 4 patterns.
Patterns of Fascicle Organization
Parallel (Fusiform): Fibers run parallel to long axis; thickens at center on contraction; can contract ~30%.
Convergent (Triangular): Broad area converges at attachment; fibers pull in different directions.
Pennate: Angled fibers; includes unipennate (e.g., extensor digitorum), bipennate (e.g., rectus femoris), and multipennate (e.g., deltoid). Develop more tension, less contraction distance than parallel.
Circular (Sphincters): Concentric arrangement; regulates openings (e.g., orbicularis oris).
Skeletal Motion
Skeletal muscles attached to skeleton produce motion; type of attachment affects movement characteristics.
Levers in Muscular System
Each bone acts as a lever with joints as fulcrums; muscles provide applied force.
Functions of a Lever: Change direction, distance, and speed of movement.
Classes of Levers
First-Class: Fulcrum between force and resistance (e.g., seesaw).
Second-Class: Resistance between force and fulcrum (e.g., wheelbarrow).
Third-Class: Applied force between resistance and fulcrum; most common in body; maximizes speed and distance.
Muscle Attachments
Each muscle has 1 origin (fixed) and 1 insertion (moving); typically, origin is proximal to insertion.
Muscle Actions and Terminology
Agonist (Prime Mover): Produces movement.
Antagonist: Opposes movement; works in pairs with agonists (e.g., flexors-extensors).
Synergist: Assists agonist, stabilizes origin.
Naming of Skeletal Muscles
Muscle names may indicate location, origin and insertion, fascicle organization, position, structural characteristics, and action.
Terms for size: Longus (long), Magnus (large), Brevis (short), etc.
Integration with Other Systems
Cardiovascular: Supplies oxygen, removes wastes.
Respiratory: Meets oxygen demand.
Integumentary: Disperses heat.
Nervous/Endocrine: Direct responses of system.
Muscle Organization and Function
Affects power, range, and speed of muscle movement.
Muscle fibers organized in bundles (fascicles); can be arranged in 4 patterns.
Patterns of Fascicle Organization
Parallel (Fusiform): Fibers run parallel to long axis; thickens at center on contraction; can contract ~30%.
Convergent (Triangular): Broad area converges at attachment; fibers pull in different directions.
Pennate: Angled fibers; includes unipennate (e.g., extensor digitorum), bipennate (e.g., rectus femoris), and multipennate (e.g., deltoid). Develop more tension, less contraction distance than parallel.
Circular (Sphincters): Concentric arrangement; regulates openings (e.g., orbicularis oris).
Skeletal Motion
Skeletal muscles attached to skeleton produce motion; type of attachment affects movement characteristics.
Levers in Muscular System
Each bone acts as a lever with joints as fulcrums; muscles provide applied force.
Functions of a Lever: Change direction, distance, and speed of movement.
Classes of Levers
First-Class: Fulcrum between force and resistance (e.g., seesaw).
Second-Class: Resistance between force and fulcrum (e.g., wheelbarrow).
Third-Class: Applied force between resistance and fulcrum; most common in body; maximizes speed and distance.
Muscle Attachments
Each muscle has 1 origin (fixed) and 1 insertion (moving); typically, origin is proximal to insertion.
Muscle Actions and Terminology
Agonist (Prime Mover): Produces movement.
Antagonist: Opposes movement; works in pairs with agonists (e.g., flexors-extensors).
Synergist: Assists agonist, stabilizes origin.
Naming of Skeletal Muscles
Muscle names may indicate location, origin and insertion, fascicle organization, position, structural characteristics, and action.
Terms for size: Longus (long), Magnus (large), Brevis (short), etc.
Integration with Other Systems
Cardiovascular: Supplies oxygen, removes wastes.
Respiratory: Meets oxygen demand.
Integumentary: Disperses heat.
Nervous/Endocrine: Direct responses of system.