Foundational Principles of Biomechanics

Question 1

Define Mechanics

Answer 1

study of the motion of objects and the forces which cause that motion

Question 2

Define Rigid-body mechanics

Answer 2

one of the branches in biomechanics in which the object being analyzed is assumed to be rigid. This assumption saves considerable mathematical and modeling work without a great loss of accuracy

Question 3

Define Kinematics

Answer 3

branch of mechanics that describes the motion of a body, without regard to the forces or torques that may produce the motion

Question 4

Define Kinetics

Answer 4

branch of mechanics that describes the effect of forces and torques on the body

Question 5

What is the moment arm?

Answer 5

perpendicular distance between an axis of rotation and the line of force

Question 6

Torque/moment = ______ x ________

Answer 6

Force

moment arm

Question 7

What does torque tend to do?

Answer 7

rotate a body or segment around an axis of rotation, hence rotary force

Question 8

Define Internal Force

Answer 8

push or pull produced by a structure located within the body. Most often, internal force refers to the force produced by an active muscle

Question 9

Define Internal/External Force

Answer 9

product of an internal/external force and its internal/external moment arm

Question 10

Define Joint Reaction Force

Answer 10

force that exists at a joint, developed in reaction to the net effect of internal and external forces

Question 11

What is Mechanical advantage?

Answer 11

ratio of the internal moment arm to the external moment arm or of the output force to the input force.

Question 12

4 Functions of Levers

Answer 12

1) Create a mechanical advantage (MA)
2) Magnify the force (possible when MA is > 1)
3) Increase the speed and range of motion through which the end of the lever moves (possible when MA is < 1)
4) Balance equal forces (when MA is equal to 1)

Question 13

What determines lever type?

Answer 13

The relative positions of the fulcrum (F), the resistance (R) and the effort (E)

Question 14

Describe a Class 1 Lever

Answer 14

Fulcrum is located in the middle of the resistance and effort

Question 15

With first class levers what does the mechanical advantage equal?

Answer 15

greater/less/equal to 1

Question 16

With a first class lever, when the fulcrum is closer to the force what is the main focus of the lever?

Answer 16

Speed and ROM

Question 17

With a first class lever, when the fulcrum is closer to the ressitance what is the main focus of the lever?

Answer 17

Strength

Question 18

Examples of First Class Levers

Answer 18

• Neck extension

- Erector spinae and Splenius

Question 19

Describe a Class 2 Lever

Answer 19

Resistance in the middle and there is an advantage in force

Question 20

With second class levers what does the mechanical advantage equal?

Answer 20

MA is greater than1

Question 21

Examples of Second Class Levers

Answer 21

• Standing on tip-toe

- Whole body pushup

Question 22

Describe a Class 3 Lever

Answer 22

Effort is in the middle which leads to an advantage in speed and ROM

Question 23

With third class levers what does the mechanical advantage equal?

Answer 23

MA is less than 1

Question 24

Examples of Third class levers

Answer 24

Elbow flexion - Biceps Brachii and Brachialis

Question 25

Most muscle and joint systems within the body function as ____ class levers.

Answer 25

third