L27

Question 1

Torque in the Human Body broken down

Answer 1

T= F x r
Force= muscle
Moment arm= bones
Torque would causes rotation about a joint for locomotion, etc

Question 2

The product of muscle tension and muscle moment arm produces

Answer 2

Torque at the joint crossed by the muscle

Question 3

The moment arm for a muscle is the

Answer 3

Perpendicular distance from the muscle line of action to the joint center
-it will change for a muscle will change as the segment moves through the ROM

Question 4

Tibiofemoral joint (knee) moves into extension, the moment arm of the quads will

Answer 4

Decrease -anterior side of the body
-axis of rotation is the knee for the thigh and shank

Question 5

As the talocrural (ankle) joint moves into plantar flexion, the moment arm of the gastric and soles will

Answer 5

Increase -changes the angle of the foot to the shank

Question 6

Joint torques

Answer 6

Produce movement of body segments
-muscles pull on points across a center of rotation, creating torque
-agonistic and antagonistic muscles are working so the change in joint position is a result of net torque

Question 7

Joint Torque can be measured Directly or Indirectly

Answer 7

Directly: place a strain gauge in the muscle
Indirectly: EMG, isokinetic device

Question 8

Components of a Lever System: (3)

Answer 8

Axis/ Fulcrum
Force Applied
Resistance

Question 9

Axis/ Fulcrum

Answer 9

Axis of rotation of the system
-rotation will occur around the fulcrum
-joints in the body

Question 10

Force Applied

Answer 10

Amount of force applied to the lever
-used to rotate some resistance around the fulcrum
-bones in the body

Question 11

Resistance

Answer 11

Weight -what you try to move
-amount applied to the lever system that opposes force applied
-muscle in the body

Question 12

ARF RULE FOR LEVERS

Answer 12

If axis is in the middle, its a first class
If Resistance is in the middle, its a second class
If Force is in the middle, its a third class

Question 13

First class lever:

Answer 13

Arrangement: FAR or RAF
-balance 2 forces and changes direction of applied force
-cervical spine and cranium
Ex) force is applied by neck extensors, vertebrae is axis, weight of the head is resistance

Question 14

Second Class Lever

Answer 14

Arrangement: ARF or FRA
-favours force production because the force arm will always be greater than the resistance arm
-least common in the body
Ex) wheelbarrow
-talocrural joint -force applied by gastric and soleous, forefoot is axis, resistance is from the leg

Question 15

Third Class Levers

Answer 15

Arrangement: RFA or AFR
-favour speed and ROM, not force production
-most common in body
Ex) humeroulnar, tibiofemoral, cocofemoral joints
-force applied by muscle, axis is joint center, and resistance is distal segment

Question 16

A second class lever does what

Answer 16

Favours force production