-muscles responsible for producing a particular movement

muscles that oppose or reverse a movement

-aid sthe action of agonists either by assisting with the same movement or by reducing undesirable or unnecessary movement

-immobilize the origin of a prime mover so that all the tension is exerted at the insertion
-specialized synergists

-any straight muscle

- at right angles to the axis

- in a slanted position

largest

smallest

long

short

triangular

-muscle of eyelids
ORIGIN: frontal and maxillary bones and ligaments around orbit
INSERTION: encircles orbit and inserts in tissue of the eyelid
ACTION: closes eyes, blinking, squinting

-extends diagonally from the corner of mouth to cheekbone
ORIGIN: zygomatic bone
INSERTION: skin and muscle at corner of mouth
ACTION: raises lateral corners of mouth upward (smiling muscle)

-multilayered muscle of lips with fibers that run in many different directions

-principal muscle of cheek; runs horizontally deep into the masseter