Muscles system

Muscle

Tissue that can contract to produce movement, make up nearly half the body's mass.

Skeletal muscle

Striated and voluntary muscle attached to bones, responsible for movements of limbs.

Cardiac muscle

Striated and involuntary muscle found in the heart, responsible for pumping blood.

Smooth muscle

Unstriated and involuntary muscle found in walls of hollow organs, responsible for involuntary movements.

Contractility

The ability of muscle fibers to shorten forcibly when adequately stimulated.

Endomysium

Delicate connective tissue sheath surrounding each muscle fiber.

Perimysium

Coarser connective tissue that wraps bundles of muscle fibers called fascicles.

Epimysium

Connective tissue sheath that covers the entire skeletal muscle.

Tendon

Strong, cordlike connective tissue that attaches muscle to bone.

Aponeurosis

Sheetlike connective tissue that connects muscles to the parts they move.

Myofilaments

Contractile proteins, actin (thin filaments) and myosin (thick filaments) that slide past each other during muscle contraction.

Action Potential

An electrical impulse that travels along the sarcolemma of the muscle cell, triggering contraction.

Neuromuscular Junction

The connection point between a motor neuron and a skeletal muscle fiber, where acetylcholine acts.

Oxygen Deficit

A condition occurring during strenuous muscle activity when oxygen supply is insufficient for aerobic respiration.

Muscle Fatigue

The inability of a muscle to contract despite being stimulated, often due to depletion of ATP or accumulation of lactic acid.

Isotonic Contraction

Type of muscle contraction where muscle shortens and movement occurs.

Isometric Contraction

Type of muscle contraction where muscle length does not change; tension increases without movement.

Prime Mover

The muscle that has the major responsibility for causing a specific movement.

Antagonist

Muscle that opposes or reverses a movement.

Synergist

Muscle that aids a prime mover in a movement.

Fixator

Specialized synergist that stabilizes the origin of a prime mover so that tension is exerted at the insertion.

Dorsiflexion

Movement of the foot that raises the toes toward the shin.

Plantar Flexion

Movement of the foot that points the toes away from the shin.

Abduction

Movement of a limb away from the midline of the body.

Adduction

Movement of a limb toward the midline of the body.