Contraction types

Isometric contraction

Muscle shortening but no movement 

Isotonic contraction: Concentric

Shortening with movement

Isotonic contraction: Eccentric

Elongation with movement

Muscle fascicle arrangement: Fusiform

Muscle fascicle arrangement: Parallel

Muscle fascicle arrangement: Triangular “convergent”

Muscle fascicle arrangement: Unipennate

Muscle fascicle arrangement: Bipennate

Muscle fascicle arrangement: Multipennate

Muscle fascicle arrangement: Circular “sphincters”

Origin

Stable segment of a muscle, typically proximal

Insertion

Moveable segment of a muscle, typically distal

Agonist

Prime mover of a joint during contraction

Antagonist

Opposes the prime mover

Synergist

Assists the prime mover

Fixator

Prevents movement, “fixates” a bone