Prime Movers/Agonists

-muscles responsible for producing a particular movement
Anatagonists

muscles that oppose or reverse a movement
Synergists

-aid sthe action of agonists either by assisting with the same movement or by reducing undesirable or unnecessary movement
Fixators
-immobilize the origin of a prime mover so that all the tension is exerted at the insertion
-specialized synergists
Rectus

-any straight muscle
Transverse

- at right angles to the axis
Oblique

- in a slanted position
Maximus

largest
Minimus

smallest
Longus

long
Brevis
short
Deltoid

triangular
Orbicularis Oculi

-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
Zygomaticus (major and minor)

-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)
Orbicularis Oris

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

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