Chapter 2 Flashcards
biomechanics
focuses on the mechanics through which the musculoskeletal components interact to create movement
fleshy attachment
muscle to bone attachment often found at the proximal end of a muscle where the muscle fibers are directly fixated to the bone
fibrous attachment (tendons)
muscle to bone attachment that is blends into and is continuous with both the muscle sheaths and the connective tissue surrounding the bone, very strong union
agonist (prime mover)
the muscle most directly involved in bringing about a movement
antagonist
a muscle that can slow down or stop the movement that is happening, assists in joint stabilization
synergist
a muscle that assists indirectly in a movement or controls body motion when the agonist is a muscle fiber that crosses two joints
first class lever
a lever for which the muscle force and resistive force act on OPPOSITE sides of the fulcrum
fulcrum
the pivot point of a lever
lever
a rigid or semirigid body that exerts force on any object impeding its tendency to rotate when subjected to a force whose line of action does not pass through its pivot point
mechanical advantage
the ratio of the moment arm through which an applied force acts to that through which a resistive force acts
mechanical advantage ratio greater than 1
mechanical advantage ratio that allows the applied muscle force to be less than the resistive force to produce an equal amount of torque
mechanical advantage ratio less than 1
mechanical advantage ratio that indicates that one must apply a greater muscle force than the amount of resistive force present, creating an obvious disadvantage for the muscle
moment arm (force arm, lever arm, torque arm)
the perpendicular distance from the line of action of the force to the fulcrum
muscle force
force generated by biochemical activity, or the stretching of non-contractile tissue, that tends to draw the opposite end of a muscle toward each other
resistive force
torce generated by source external to the body that acts contrary to muscle force
second class lever
a lever for which the muscle force and resistive force act on the SAME side of the fulcrum with the muscle force, acting through a moment arm LONGER than that through which the resistive force acts
third class lever
a lever for which the muscle force and resistive force act on the SAME side of the fulcrum, with the muscle force acting through a moment arm SHORTER than that through which the resistive force acts (mechanical advantage is thus < 1)
torque (moment)
the degree to which a force tends to rotate an object about a specified fulcrum, defined quantitively as the magnitude of a force times the length of its moment arm
smaller
due to the mechanical advantage of a second class lever, the required muscle force is smaller or larger than the resistive force?
greater
due to the mechanical advantage of a third class lever being less than 1, the muscle force has to be smaller or greater than the resistive force to produce a torque equal to that produced by the resistive force?
strength
the ability to exert force at any given speed
acceleration
change in velocity per unit of time
power
time rate of doing work, “explosive strength”
work
product of the force exerted on an object and the distance the object moves in the direction in which the force is exerted
newtons (N)
SI unit for force
meters (m)
SI unit for distance
joules (J)
SI unit for work
seconds (s)
SI unit for time
watts (W)
SI unit for power
disadvantage (requires MORE force)
do most muscles work at a mechanical advantage or disadvantage?