Muscle System

Skeletal muscle

Striated muscle that is connected to bones and is responsible for voluntary movements.

Cardiac muscle

Striated muscle found only in the heart; contains intercalated discs and is involuntary.

Smooth muscle

Non-striated muscle found in the walls of hollow organs; involuntary.

Epimysium

Connective tissue that surrounds the entire muscle belly.

Perimysium

Connective tissue that surrounds individual fascicles within a muscle.

Endomysium

Connective tissue that surrounds individual muscle fibers.

Tendons

Structures that attach muscles to bones.

Origin

The fixed end of a muscle that remains stationary during contraction.

Insertion

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

Prime mover

The main muscle responsible for performing a specific movement.

Synergist

Muscles that assist the prime mover in performing a movement.

Fixator

Muscles that stabilize joints during movement.

Antagonist

Muscle that opposes the action of the prime mover.

Flexion

Decreasing the angle between two body parts.

Extension

Increasing the angle between two body parts.

Abduction

Movement away from the midline of the body.

Adduction

Movement towards the midline of the body.

Pronation

Rotational movement of the forearm, turning the palm downward.

Supination

Rotational movement of the forearm, turning the palm upward.

Inversion

Movement of the foot that turns the sole inward.

Eversion

Movement of the foot that turns the sole outward.

Plantarflexion

Extending the foot downward, as when pressing a gas pedal.

Dorsiflexion

Flexing the foot upward, as when easing off a gas pedal.

Elevation

Movement that raises a body part upward.

Depression

Movement that lowers a body part downward.

Rotation

Movement around a central point or axis.

Anterior group

Muscle group in the thigh responsible for extending the knee.

Posterior group

Muscle group in the thigh responsible for flexing the knee.

Medial group

Muscle group in the thigh responsible for adducting the thigh.

Sartorius

Muscle that separates the anterior compartment from the medial compartment in the thigh.

Muscle Actions

Different movements performed by muscles during contraction.