4.2 Joint Movement, and muscle contractions

Question 1

Extension of a joint is best described as…

Answer 1

Increasing the angle between the two bones involved in that particular movement. (hinge joints always move with flexion an extension)

For example knee, flexion, and extension.

Knee extension increases the angle between the tibia and femur.

(see image attached)

Question 2

Flexion of a joint is best described as…

Answer 2

Decreasing the angle between the two bones involved in that particular movement. (hinge joints always move with flexion an extension)

For example knee, flexion, and extension.

Knee flexion decreases the angle between the tibia and femur.

(see image attached)

Question 3

Explain the concept of reciprocal inhibition.

Answer 3

Muscles pull on joints in pairs, these pairs are called antagonistic pairs.

Antagonistic pairs, work with the concept of reciprocal inhibition. The Agonist contracts while the antagonist relaxes.

When the agonist motor neuron is stimulated, the motor neuron to the antagonist is inhibited, preventing it from contracting strongly”

Question 4

Explain the movements Abduction and Adduction and give an example.

Answer 4

Abduction

The movement of a limb (arm or leg) away from the midline of the body.

Adduction

The movement of a limb (arm or leg) towards the midline of the body.

Example in pictures attached (note horizontal ab/adduction is also possible.

Question 5

What is pronation and supination and give an example?

Answer 5

The ‘twist’ movement in an limb. E.g. twisting the hand from palm up to palm down position.

Question 6

What is a Synergist muscle?

Answer 6

Assists Prime mover

When performing an exercise, other muscles may join in and assist the prime mover. These muscles are called synergists

Question 7

What is a fixator muscle?

Answer 7

Stabilizes the joint which is moving.

Muscles can also contract isometrically to stabilize the origin to maintain a correct or stable position. When a muscle performs this function it is called a fixator

Question 8

Which antagonistic pair is involved in Elbow flexion, and extension.

Answer 8

Flexion

AGONIST (prime mover) = Biceps Brachii

ANTAGONIST (relaxed) = Triceps Brachii

Extension

AGONIST (prime mover) = Triceps Brachii

ANTAGONIST (relaxed) = Biceps Brachii

Question 9

Which antagonistic pair is involved in Shoulder flexion, and extension.

Answer 9

Flexion

AGONIST (prime mover) = Anterior Deltoid & Pectoralis Major

ANTAGONIST (relaxed) = Posterior Deltoid & Latissimus Dorsi

Extension

AGONIST (prime mover) = Posterior Deltoid & Latissimus Dorsi

ANTAGONIST (relaxed) = Anterior Deltoid & Pectoralis Major

Question 10

Circumduction is possible at which type of synovial joint?

Answer 10

Ball and socket joints.

Hip joint

Shoulder joint.

Question 11

How does rotation of a joint differ from circumduction?

Answer 11

Circumduction – this is where the limb moves in a circle.
Rotation – this is where the limb turns round its long axis, like using a screw driver.

Question 12

The difference between?

Protraction - Retraction

Inversion - Eversion

Suppression - Depression.

Answer 12

Question 13

What are the 5 different muscle contractions?

Answer 13

Isotonic

Isometric

Isokinetic

Concentric and Ecentric

Question 14

Outline Isometric muscle contraction

Answer 14

Contraction with no change in muscle length

(tension but no movement)

(Ex. Arm wrestle)

Question 15

Outline Isotonic muscle contraction

Answer 15

Tension with movement, Muscles moving

Two kinds of Isotonic contraction (Concentric and Eccentric)

Question 16

Outline Isokinetic Muscle contraction

Answer 16

A muscle contracts at a constant speed

(tension with movement at a constant speed, normally in a laboratory with special equipment)

Question 17

Outline Concentric muscle contraction

Answer 17

Shortening of the muscle fibers (contracting bicep Brachii)

Question 18

Outline eccentric muscle contractions

Answer 18

When the muscle is lengthening (Arm going down out of curl)

Question 19

What is DOMS

Answer 19

DOMS is Delayed Onset Muscle Soreness

Question 20

DOMS in relation to Concentric and eccentric muscle contractions

Answer 20

DOMS typically comes from eccentric muscle contractions and it causes the muscle to have small tears. The small tears give the soreness

Running down a steep hill your quadriceps is eccentrically contracting causing DOMS