2 Origin- fixed point of attachment; for biceps brachii O= clavicle and humerus Insertion- moveable, usually crosses a joint; O= radiusPrime mover- - muscle group responsible for producing particular movementAntagonist- works opposite of prime moverSynergist-reduces undesirable or unnecessary movementContraction of a muscle crossing 2 or more joints wouldcause movement of all if synergists weren’t there tostabilize itEx. make a fist without bending wristFixator- specialized synergist- helps maintain posture; ex. muscles of the back fix scapula
4 Lever Systems Lever systems: lever - rod that moves at the fulcrum (fixed point)fulcrum (F) typically the joint movingResistance (R)- gravity pulling on bodyEffort (E)- muscle contractionMovement occurs when E > RFirst class levers - E F RSecond class levers - F R EThird class levers - F E R . . (most common)
5 Lever Systems1st class lever2nd class lever3rd class lever
7 Naming Skeletal Muscles Direction of muscle fibers- straight, transverseSize of muscles- maximus, minimus, longus, brevisLocation- frontalis, temporalis, occipitalis# of origins- biceps, triceps, quadricepslocation of muscles origin and insertion-sternoclediomastoid- O= sternum and clavicle, I =mastoid process of temporal boneshape of muscle- deltoid- triangle shape, trapezius-trapezoid shapeaction of muscle- adductor muscle (adducts, bringsin thigh)
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