BIOMECHANIC OF MSK

Question 1

what is an angle of pull

Answer 1

the angle formed by the muscle force vector relative to the bone on which the muscle is attached.

Question 2

angle of pull depend on

Answer 2

joint angle, origin and insertion of muscle

Question 3

which componement never passes through the axis or rotation

Answer 3

vertical/perpendicular = rotatory component

Question 4

which component always passes through the axis of rotation

Answer 4

horizontal/parallele -> stabilizing/destabilizing component

Question 5

which component always have a moment arm that exist

Answer 5

perpendicular/vertical so its always a torque producing component

Question 6

which component doesn’t have a moment arm

Answer 6

horizontal/parallel

Question 7

A muscle that acts primarily as a stabilizer during one action may act as the _ in a different action

Answer 7

primary rotator

Question 8

hamstring and bicep are

Answer 8

rotatory and stabilizing

Question 9

gastroc and brachioradialis are

Answer 9

more stabilizing

Question 10

popliteus and brachialis are

Answer 10

rotatory and stabilizing

Question 11

bone are rigig/semi-rigid body

Answer 11

semi-rigid

Question 12

third classes lever are use to

Answer 12

to gain an advantage in linear range of motion and velocity of movement. This advantage in linear range of motion and velocity of movement comes at the price of force because the motive force has a short moment arm, and therefore a disproportionately large motive force must be produced to overcome the resistive force

Question 13

Because humans are at a mechanical disadvantage in torque production, lower rotational inertia means that

Answer 13

that less torque is necessary to angularly accelerate the limb

Question 14

what are the advantage of not having solid bone all the way to core

Answer 14

This structure keeps the mass of the segment minimal. A tube is stronger than a cylinder of the same mass in torsion and bending.

Question 15

explain limb mass distrutibution

Answer 15

the muscles that move the upper arm must be large, because the upper arm contains the muscles that move the forearm, which in turn contains the muscles that move the hand. This situation is exacerbated further because proximal segments are usually needed to drive the inertias of all of the distal segments. Second, proximal bones are more massive than distal bones. Together these variations in muscle and bone mass have direct implications for human shape in terms of rotational inertia.

Question 16

what is a tappering effect

Answer 16

. For example, the more distal portion of the forearm is less massive than the more proximal end. The distal portion of the thigh is less massive than the more proximal portion, etc. So each segment is tapered, and then superimposed on this shape, the entire limb is tapered. This fact may seem obvious visually, but it is very ingenious. Overall, most of the muscle and bone mass of a limb is located near the axis of rotation thereby reducing the moment of inertia and making the limb easier to rotate.