B3 - Antagonist muscle pairs

Question 1

What are antagonist muscle pairs?

Answer 1

• a pair of muscles that work together in order to create movement
• one contracts while the other relaxes in order to create movement

Question 2

What is a synergist?

Answer 2

• muscles that work together to enable the agonist to operate more effectively

Question 3

What is a fixator?

Answer 3

• muscles that help stabilise the joints around the origin of the movement

Question 4

What is the origin?

Answer 4

• one end of the muscle that remains stationary

Question 5

What is the insertion?

Answer 5

• the moving end of the muscle

Question 6

What happens when a stimulus is sent to a muscle?

Answer 6

• muscle fibres work on an ‘all or nothing’ basis
• this means within the muscle groups of motor units, the all or nothing rule applies to these, not each individual muscle fibre within the muscle

Question 7

What happens when a muscle contracts (in terms of antagonist muscle pairs)?

Answer 7

• on end of the muscle remains stationary (if it is an isolated movement), known as the origin
• the moving end of the muscle is known as the insertion

Question 8

Can muscles work alone?

Answer 8

• muscles work in pairs (or even groups)
• if one muscle were to contract, no movement would occur unless there is relaxation from another

Question 9

What state do muscles always appear in?

Answer 9

• ‘partial contraction’
• this is preparation to react to a stimulus from your nervous system

Question 10

Where are muscles positioned over joints?

Answer 10

• muscles cross over joints

Question 11

Can muscles push or pull?

Answer 11

• muscle can only ever pull
• they can contract without shortening to hold a joint firm fixed in a certain position
• but to allow movement they only pull on a bone

Question 12

Do muscles relax and the movement automatically go back in the opposite direction?

Answer 12

• when the contraction ends, muscles relax (go soft) but no movement occurs until its antagonist partner contracts to bring the movement back

Question 13

What is the agonist muscle?

Answer 13

• the muscle that contracts and shortens

Question 14

What is the antagonist muscle?

Answer 14

• the muscle that relaxes and lengthens

Question 15

What does the antagonist do that the movement cannot occur without?

Answer 15

• movement cannot occur without the antagonist relaxing, the antagonist also acts as a ‘brake’ and controls the movement speed

Question 16

What is the synergists job?

Answer 16

• they help control the direction of pull from the agonist and also help develop force for the movement (meaning all the force isn’t necessarily created by the agonist)

Question 17

What is the fixators job?

Answer 17

• they contract in order to reduce any un-wanted movement from the origin, meaning the agonist is more effective

Question 18

Examples of a bicep curl …
(broken down into each section and muscle)

Answer 18

agonist - bicep brachii
antagonist - tricep brachii
fixator - deltoid
synergists - brachioradialis