Origin- fixed point of attachment; for biceps brachii O= clavicle and humerus

Insertion- moveable, usually crosses a joint; O= radius

Prime mover- - muscle group responsible for producing particular movement

Antagonist- works opposite of prime mover

Synergist-reduces undesirable or unnecessary movementContraction of a muscle crossing 2 or more joints would cause movement of all if synergists weren’t there to stabilize itEx. make a fist without bending wrist

Fixator- specialized synergist- helps maintain posture; ex. muscles of the back fix scapula

Lever systems:• lever - rod that moves at the fulcrum (fixed

point) • fulcrum (F) typically the joint moving • Resistance (R)- gravity pulling on body • Effort (E)- muscle contraction • Movement occurs when E > R

1. First class levers - E F R 2. Second class levers - F R E 3. Third class levers - F E R . . (most common)

1st class lever 2nd class lever 3rd class lever

biceps(flexor)biceps(flexor)

biceps(flexor)biceps(flexor)

triceps(extensor)

triceps(extensor)

triceps(extensor)

triceps(extensor)

• Direction of muscle fibers- straight, transverse• Size of muscles- maximus, minimus, longus, brevis• Location- frontalis, temporalis, occipitalis• # of origins- biceps, triceps, quadriceps • location of muscles origin and insertion- sternoclediomastoid- O= sternum and clavicle, I = mastoid process of temporal bone• shape of muscle- deltoid- triangle shape, trapezius- trapezoid shape• action of muscle- adductor muscle (adducts, brings in thigh)

Sternoclediomastoid

Frontal

Temporalis

MasseterObicularis orisObicularis oculi

                                                                                                                         

Frontalis

Orbicularis oris

Orbicularis oculi

Masseter

sternocledeomastoid

zygomaticus

aponerosa

temporalis