Muscular System Ch 11

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

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

biceps (flexor) triceps (extensor) triceps (extensor) Antagonistic Muscles triceps (extensor) biceps (flexor)

Naming Skeletal Muscles 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)

Frontal Obicularis oculi Temporalis Obicularis oris Masseter Sternoclediomastoid

                                                                                                                         

Masseter sternocledeomastoid Frontalis aponerosa Orbicularis oculi temporalis zygomaticus Orbicularis oris Masseter sternocledeomastoid