Skeletal Muscles

These flashcards cover key vocabulary related to skeletal muscles, their structure, function, and actions.

Skeletal Muscles

Muscles that are attached to the skeleton and responsible for movement, comprising 44% of body mass.

Tendons

Connective tissues that attach muscles to bones and cartilage.

Isotonic contraction

A type of muscle contraction where tension changes and muscle length changes; includes concentric (shortening) and eccentric (lengthening) contractions.

Agonist

The primary muscle that performs an action; also known as the prime mover.

Synergists

Muscles that assist the agonist in performing an action.

Antagonists

Muscles that oppose the action of the agonist.

Fixators

Muscles that stabilize the origin of the agonist and the joints they span.

Origin

The immovable end of a muscle where it attaches to a bone.

Insertion

The movable end of a muscle that is pulled toward the origin during contraction.

Muscle Fiber

The individual cells of skeletal muscle, composed of myofibrils.

Myofibril

A long, threadlike structure composed of actin and myosin filaments that make up muscle fibers.

Actin filaments

Thin protein filaments involved in muscle contraction.

Myosin filaments

Thick protein filaments involved in muscle contraction.

Troponin

A protein that binds calcium and facilitates muscle contraction by moving tropomyosin away from myosin-binding sites.

Tropomyosin

A protein that blocks myosin-binding sites on actin filaments in muscle fibers.

Sarcomere

The basic contractile unit of muscle fiber, defined by the area between two Z lines.

Cross-bridge

The connection formed between actin and myosin filaments during muscle contraction.

Muscle relaxation

The process by which the muscle returns to its original length after contraction, involving active transport of Ca²+ back into the sarcoplasmic reticulum.