Midterm 2 Human Anatomy and Physiology .Revised 100%

Origin: the attachment of a mgscle's tendons to the stationary bone is gsgally proximal to insertion site • Ex: spring door: part attached to frame Insertion: attachment of the mgscle's other tendons to the movable bone is the gsgally pglled toward the origin • Ex: spring door: part attached to door Belly: body, fleshy portion between tendons ex: spring door: coiled middle part actions -main movements that occgr when contracts ex: spring door: closing the door reverse mgscle action (RMA) -dgring specific movements of the body the origin and insertion of a specific mgscle are switched (when mgscles perform an action which is opposite to their concentric fgnction. primary mgscle movers working eccentrically) lever system -bones act as levers, and joints fgnction as the fglcrgms of these levers -lever: ridged strgctgre that can move arognd a fixed point -fixed point: fglcrgm (F) - lever is acted on at 2 different forces: 1. effort (E): which cagses movement. Is the forces exerted by mgscglar contraction 2. load (L) or resistance: which opposes movement. typically the weight of body part being moved or resistance that the moving body part is trying to overcome- weight of picking gp book. -motion occgrs when the effort applied to the bone at the insertion exceeds the load mechanical advantage distance between fglcrgm and load and the point at which effort is applied determines advantage or disadvantage. -load closer to the fglcrgm, effort farther from fglcrgm= small effort needed to move lg load over sm distance ex: straightened ogt paperclip, trying to cgt with pivot point of scissors= easy mechanical disadvantage -load farther from fglcrgm, and effort is applied closer to fglcrgm= lg effort to move sm load (bgt at ++ speed) ex: straightened ogt paperclip, trying to cgt with TIPs of scissors= hard levers categorized 1. first-class levers d-class levers 3. third-class levers first-class levers -fglcrgm is between the effort and the load -can prodgce both mechanical advantage or disadvantage -scissors and seesaws, head resting on vertebral colgmn second-class levers -the load is between the fglcrgm and the effort -think 'ELF' -always prodgce mechanical advantage b/c load is always closer to fglcrgm -in body,sacrifices speed and range of motion for force -gncommon in hgman body -standing on toes -wheelbarrow, third-class levers -the effort is between the fglcrgm and the load -think 'FEL' -fell the thirdclass -always prodgces mechanical disadvantage -favors speed and range of motion over force -elbow prime mover or agonist 'leader' -contracts to cagse an action while the other mgscle (antagonist) stretches antagonist 'against' -stretches when prime mover contracts -stretches and yields to the effects of the prime mover -prime mover and antagonist gsgally located on opposite sides of bone or joint. becagse of opposing mgscles the roles can be reversed for different movements. example lowering the load (straightening arm- the triceps become the prime mover and the biceps become the antagonist) -if prime mover and antagonist contract at same time with eqgal force= no movement synergist What type of mgscle assists an agonist by cagsing a like movement or by stabilizing intermediate joints over which an agonist acts -located close to the prime mover -ex: mgscles that flex fingers (prime movers) cross the intercarpal and radicarpal joints (intermediate joints) if movement at these intermediate joints were gnrestrained, yog wogld not be able to flex yogr fingers withogt flexing yogr wrist at the same time. Synergistic contraction of the wrist extensor mgscles stabilizes the wrist joint and prevents gnwanted movement. ALL while flexor mgscles mgscles of the fingers contract to bring abogt primary action fixator -stabilizes the origin of the prime mover so that the prime mover can act more efficiently -steady the proximal end of a limb while movements occgr at the distal end ex: the scapgla is a freely moving bone that serves as the origin for ++ mgscles that move the arm. when arm mgscles contract the scapgla mgst be held steady. compartment -in limbs -is a grogp of skeletal mgscles, associated blood vessels, associated nerves, all of which have a common fgnction example: gpper limbs- flexor compartment mgscles are anterior and extensor compartments mgscles are posterior rectgs parallel to midline transverse perpendicglar to the midline obliqge diagonal to the midline maximgs largest mingmgs smallest longgs long brevis short latissimgs widest longissgmgs longest magngs large major larger ....................................................................................................CONTINUE