Musculoskeletal

Question 1

Define 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

What does the angle of pull depend on

Answer 2

The origin and insertion of the individual muscle

Question 3

What does the angle of pull vary with?

Answer 3

• The joint angle
• The origin and insertion

Question 4

What is the rotary component of the resultant force vector?

Answer 4

vertical/perpendicular ocmponent

Question 5

T/F The vertical/perpendicular component never passes through the axis of rotation

Answer 5

True

Question 6

What is the stabilizing/ destabilizing component of the resultant force vector?

Answer 6

The horizontal/parallel component

Question 7

T/F The horizontal/parallel component never passes through the axis of rotation

Answer 7

False, it always passes through the axis of rotation

Question 8

The angle of pull affect the ______ ______ of the _____ and ____ components of the resultant vector

Answer 8

Relative magnitudes; perpendicular; parallel

Question 9

What does the angle of pull also affect?

Answer 9

The direction of the parallel component of the resultant vector

Question 10

T/F A muscle that acts primarily as a stabilizer during one action may act as the primary rotator in a different action

Answer 10

True

Question 11

Why can’t some muscles achieve every angle of pull?

Answer 11

Because of constraints of origin and insertion

Question 12

Hamstrings

Answer 12

Rotary and stabilizing/destabilizing

Question 13

Gastrocnemius

Answer 13

stabilizing

Question 14

Popliteus

Answer 14

Rotary and stabilizing/ destabilizing

Question 15

Links = _____

Answer 15

joints

Question 16

Bones = _____

Answer 16

Semi-rigid bodies

Question 17

How is force applied in the human body and what does it cause

Answer 17

Force is applied to segments by muscle contractions causing motion at the joints

Question 18

What is the most abundant type of lever in the human body

Answer 18

Third class lever

Question 19

Where is the motive force (muscle) in a third class lever system?

Answer 19

Between the fulcrum (joint) and resistive force (segment)

Question 20

Why does human torque production have a mechanical disadvantage?

Answer 20

Because it uses a third class lever system

Question 21

How do you compensate for mechanical disadvantage?

Answer 21

reducing segments moment of inertia

Question 22

How do you reduce a segments moment of inertia

Answer 22

• reduce the mass
• keep the mass close to the axis of rotation

Question 23

What reduces mass in the body

Answer 23

Bones because they are hollow

Question 24

Where are the muscles located that move one segment

Answer 24

They are located on the more proximal segment

Question 25

What is the only thing attached to the segment of interest?

Answer 25

The distal tendon

Question 26

Each successively proximal segment must have _____ muscle ____ because more ____ is needed

Answer 26

more; mass; torque

Question 27

Why is more torque needed for limb mass distribution?

Answer 27

• To accelerate each progressively more massive segment
• to drive the inertias of all distal segments

Question 28

What kind of effect is created in limb mass distribution

Answer 28

A tapering effect

Question 29

Where is most of the mass located and what does it lower?

Answer 29

Most of the mass is located near the axis of rotation and it lowers the rotational inertia