Origin fixed point of attachment for biceps brachii

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 movement Contraction of a muscle crossing 2 or more joints would cause movement of all if synergists weren’t there to stabilize it Ex. 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)

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

biceps (flexor) triceps (extensor) biceps (flexor)

• 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)

Temporalis Frontal Obicularis oculi Obicularis oris Masseter Sternoclediomastoid

Frontalis aponerosa Orbicularis oculi temporalis zygomaticus Orbicularis oris Masseter sternocledeomastoid