BIOLOGY 235 MIDTERM 2 REVIEW

BIOLOGY 235 MIDTERM 2 REVIEW CHAPTER 11: THE MUSCULAR SYSTEM origin - stationary bone, usually proximal Insertion - attachment of muscle's other tendon to movable bone, usually distal belly (body) - fleshy portion of muscle between their tendons (origin and insertion) Actions - main movements that occur when the muscle contracts reverse muscle action (RMA) - during specific movements the actions are reversed; • bones act as levers, and joints function as the fulcrums of these levers • lever: rigid structure that can move around a fixed point called a fulcrum • effort: causes movement force exerted by muscular contraction • load or resistance: opposes movement. • the load is typically the weight of the body part that is moved or some resistance that the moving body part is trying to overcome - motions occur when effort applied at insertion exceeds the load mechanical advantage - only needs small amount of force to move load over small distance mechanical disadvantage - larger amount of force to overcome load Lever types (3) 1. first-class levers - scissors and seesaws a. produce either mechanical advantage or disadvantage b. fulcrum is between effort and the load 2. second-class levers - wheelbarrow a. always produce mechanical advantage b. sacrifices speed and ROM for force c. load is between fulcrum and the effort 3. third-class levers - most common in body a. produce mechanical disadvantage b. favors speed and ROM over force c. effort between the fulcrum and the load prime mover or agonist – contracts, causes an action antagonist - stretches, yields to prime mover synergists - aid movement of prime mover, prevent unwanted movement Fixators - stabilize origin of prime mover, so it can move more efficiently Compartment - group of skeletal muscles, blood vessels and associated nerves have a common function - eg. upper limbs: flexor compartment is anterior and extensor compartment is posterior Classification of Skeletal Muscles (2): 1) Terms that refer to muscle features: pattern/direction of fascicles, size, shape, action, number of origins and location 2) Sites of origin and insertion of the muscle