Biomechanics Part 2

Question 1

What do kinetics describe?

Answer 1

the effect of forces on the body

Question 2

Define internal forces

Answer 2

Forces derived from inside the body

Question 3

Define external forces

Answer 3

Forces derived from outside the body

Question 4

Define the two internal forces types

Answer 4

Active: activated muscles
Passive: passive tension in stretched tissues (involves give and release of tension/force)

Question 5

What are external forces? examples?

Answer 5

wind, gravity, friction

things we adapt our movement to

Question 6

Where is the point of application for musculoskeletal forces?

Answer 6

Where the forces are applied in the joint’s axis of rotation

these forces act on the center of mass of all external forces

Question 7

What is the angle of insertion?

Answer 7

how the muscle’s insertion is relative to the long axis of the bone

Question 8

What does a change in the angle of insertion do to the direction of force?

Answer 8

brings the force in multiple other directions

Question 9

Define the moment arm

Answer 9

Distance between the force acting on the body and its axis of rotation

Question 10

Joint moment is equal to

Answer 10

Muscle force * Moment arm

Question 11

Define Static Equilibrium

Answer 11

Internal and external forces equal one another

Question 12

Explain Joint Reaction force

Answer 12

the muscle wants to translate the moment, but the joint and bone opposing that movement provide force in the opposite direction

Question 13

Define Static Rotary Equilibrium

Answer 13

Internal moment = External moment

muscle force * internal moment arm = external force * external moment arm

Question 14

What creates a mechanical advantage?

Answer 14

A longer moment arm

Question 15

What are the three types of muscle activation?

Answer 15

Isometric, Concentric and Eccentric

Question 16

Define Isometric muscle activation

Answer 16

Muscle produces force while maintaining a constant length

Question 17

Define Concentric muscle activation

Answer 17

Muscle produces a force while shortening

Internal moment > external moment

Question 18

Define Eccentric muscle activation

Answer 18

Muscle produces a force while lengthening

External moment > internal moment

Question 19

Two muscle action concepts

Answer 19

when a muscle contracts, the freest segment moves

a muscle action can be produced if a moment arm or mechanical advantage is present for that plane of motion

Question 20

Force couple definition

Answer 20

Forces in opposite directions can produce a movement in one direction

Question 21

In Static Linear Equilibrium, what role do the biceps muscle force, weight of the forearm, and reaction force of the humerus pushing down play?

Answer 21

Biceps: internal force
External force: weight of forearm
humerus: reaction force

Question 22

Define muscle action

Answer 22

The potential for a muscle to produce osteokinematic rotation around an axis of rotation in a plane of motion

Question 23

Define an agonist muscle/muscle group

Answer 23

m. /m. group most directly related to the initiation or execution of a movement
ex. biceps are the agonist of elbow flexion

Question 24

Define an antagonist muscle/muscle group

Answer 24

m. /m. group that has the opposite action of the agonist m. or m. group
ex. triceps are the antagonist of elbow flexion