Muscle form + action at Joints

Question 1

What influences movement of muscles

Answer 1

*It’s attatchment to bone –> lever
*Muscle structure i.e length, no. of fibres and arrangement
*Types of contraction
*Location of the muscle to the joint

Question 2

What is the lever?

Answer 2

Bones

Question 3

What is the pivot point?

Answer 3

The joint

Question 4

What is the load?

Answer 4

The weight

Question 5

How does a lever aid in movement

Answer 5

The muscle pulls on the lever to lift the load

Question 6

What are the different types of levers

Answer 6

Class 1
Class 2
Class 3

Question 7

Class 1 lever

Answer 7

For balance and stability, fulcrum in between load and applied force eg. See saw

In the body, the load is the head, the fulcrum is the atlanto-occipital joint and the AP is the muscles contracting to pull the head up

Question 8

Class 2 lever

Answer 8

For effectively lifting heavy loads, fulcrum at the end, load in the middle and AP at other end eg wheelbarrow

The leg where the pivot is the toes, the Load runs through the bone and applies down and the AP is the gastrocnemius contracting to lift up

Question 9

Class 3 lever

Answer 9

For large range of motion + speed, the fulcrum at the end, applied force in the middle and the load at the end eg tongs/fishing rod

Dumbell in the hand, the pivot is the elbow and the AP is the bicep contracting to pull weight up. The fulcrum is closer to the AP

Question 10

Points of muscle structure

Answer 10

*Length
*number of muscle fibres
*Arrangement

Question 11

How much can fibres shorten?

Answer 11

upto 50% of resting muscle length

Question 12

What kind of muscle fibre is required for a large ROM?

Answer 12

Long muscle fibres

Question 13

How does number of muscle fibres influence movement?

Answer 13

The tension is proportional to the CSA. Therefore, if there are more muscles fibres in the CSA of a muscle = more tension i.e can life more heavier stuff

Question 14

Two types of muscle fibre arrangement

Answer 14

Parallel and Pennate

Question 15

Parallel muscle fibre arrangement

Answer 15

runs in straight lines besides each other and in between tendons

Less muscle fibres fit so less tension but better for ROM

Question 16

Pennate muscle fibre arrangement

Answer 16

Runs obliquely, more muscle fibres can fit between tendons so more tension BUT can only contract half the shortest arrangement so not a lot of ROM

Question 17

What are the types of muscle action?

Answer 17

*Concentric
*Eccentric
*Isometric

Question 18

Concentric

Answer 18

The muscle is active, tension is developing and the tension is greater than the load so muscle shortens

Decreases angle between levers

Question 19

Eccentric

Answer 19

The muscle is active, tension is developing but the tension is lesser than the load so muscle elongates

Angle increases between the levers

Could be the pull in opp. direction due to another muscle/Gravity

Question 20

Isometric

Answer 20

The muscle is active, tension is developing
Tension = load
No change in muscle/ joint position

Question 21

Muscle roles

Answer 21

*Agonost
*Antagonist
*Stabiliser
*Neutraliser

Question 22

Agonist

Answer 22

*Moves concentrically to initiate a movement eg biceps brachii contracts to lift something

Question 23

Antagonist

Answer 23

*Moves eccentrically to appose an agonist movement, controls the action of the agonist and makes sure its smooth Eg triceps brachii elongates to appose biceps brachii contracting

Question 24

Stabiliser

Answer 24

*Holds joint in position i.e stable + still, isometric activity

Question 25

Neutraliser

Answer 25

Eliminates an unwanted movement caused by another muscle eg. pronator muscles act as neutralisers in the arm to prevent supination when lifting a glass of water

Question 26

The rule for muscle contraction with reference to the relative position of the muscle to the joint

Answer 26

Anterior - flexion
Posterior - extension
Lateral - abduction
Medial - Adduction

Question 27

What do the muscles cause?

Answer 27

Movement towards itself