The Muscular System

A set of vocabulary flashcards covering key concepts and terminology related to the muscular system and its organization, function, and interactions with other body systems.

Muscle Organization

Affects power, range, and speed of muscle movement.

Fibers

Muscle cells organized in bundles called fascicles.

Fascicles

Bundles of muscle fibers aligned parallel.

Fascicle Arrangement Patterns

4 patterns: parallel, convergent, pennate, circular.

Parallel Muscles

Fibers run parallel to the long axis; contraction thickens the muscle.

Fusiform Muscles

A type of parallel muscle; e.g., biceps brachii.

Convergent Muscles

Fibers pull in different directions towards one attachment site.

Triangular Muscle Example

Pectoralis muscles are convergent muscles.

Pennate Muscles

Muscles with fibers at angles to tendons; includes unipennate, bipennate, and multipennate.

Unipennate Muscle Example

Extensor digitorum has fibers angled on one side.

Bipennate Muscle Example

Rectus femoris has fibers angled on both sides.

Multipennate Muscle Example

Deltoid has tendon branches within muscle.

Muscle Contraction

Pennate muscles develop more tension than parallel muscles.

Circular Muscles

Also known as sphincters; open and close entrances of the body.

Orbicularis Oris

Example of a circular muscle; guards the mouth.

Skeletal Motion

Produced by attachment of muscles to bones.

Lever

A rigid structure that moves around a fulcrum.

Fulcrum

The fixed point around which a lever moves.

Applied Force (AF)

Force applied by muscle to overcome resistance.

Resistance (R)

The weight or load the muscle works against.

First-Class Levers

Fulcrum is between applied force and resistance; e.g., seesaw.

Second-Class Levers

Resistance is between fulcrum and applied force; e.g., wheelbarrow.

Third-Class Levers

Applied force is between resistance and fulcrum; most common in the body.

Origin

The fixed point of muscle attachment.

Insertion

The moving point of muscle attachment.

Flexion

A type of body movement produced by muscle contraction.

Extension

A movement that straightens a joint.

Agonist

The prime mover that produces a specific movement.

Antagonist

Muscle that opposes the action of the agonist.

Synergist

A smaller muscle that assists a larger agonist.

Muscle Opposition

Agonists and antagonists work in pairs to create movement.

Descriptive Names for Skeletal Muscles

Based on location, origin/insertion, fascicle organization, position, characteristics, and action.

Temporalis Muscle

An example of naming based on location in the body.

Origin and Insertion Naming

First part indicates origin, second indicates insertion.

Rectus Muscle

Example of fascicle organization; means straight.

Externus Muscle

Visible at the body surface; superficial.

Internus Muscle

Deep muscles, not visible at the surface.

Bi and Tri in Muscle Naming

Indicates number of tendons; bi = 2, tri = 3.

Trapezius Muscle Shape

Descriptive name based on shape; trapezoid.

Longus

Indicates long muscle.

Brevis

Indicates short muscle.

Maximus

Indicates largest muscle.

Risor Muscle

Action-related name for muscle associated with laughter.

Integration with Other Systems

Muscles work with cardiovascular, respiratory, and other systems in the body.

Cardiovascular System Role

Delivers oxygen and nutrients to muscles.

Respiratory System Role

Responds to oxygen demand of muscles.

Integumentary System Role

Disperses heat produced by muscle activity.

Nervous and Endocrine Systems Role

Direct responses of all body systems during muscle activity.