Back Muscles

Question 1

What do extrinsic muscles do?

Answer 1

Upper limb movement.
Respiration.

Question 2

What do intrinsic muscles do?

Answer 2

Maintains posture.
Controls movement of the vertebral column.

Question 3

What causes flexion?

Answer 3

Bilateral.
Muscles anterior to the spine.
Rectus abdominis and psaos major.

Question 4

What causes extension?

Answer 4

Bilateral.
Muscles posterior to the spine.
Erector spinae.

Question 5

What causes rotation?

Answer 5

Unilateral.
Muscles with oblique fibre orientation.
External obliques, internal obliques and erector spinae.

Question 6

What causes lateral flexion?

Answer 6

Unilateral.
External obliques, internal obliques and erector spinae.

Question 7

What is the function of anterior abdominal muscles?

Answer 7

Three large flat muscles with different fibre orientations.
Rectus abdominis, transversus abdominis and obliques.
Anterior flexion / lateral flexion / rotation of the trunk.

Question 8

What is the function of posterior abdominal muscles?

Answer 8

Illiacus, psoas major and quadratus.
Anterior flexion (psoas major) / lateral flexion.

Question 9

What is the function of the erector spinae?

Answer 9

Intrinsic muscles.
Extension - bilateral.
Lateral flexion - unilateral.

Question 10

Why are the anterior abdominal muscle fibres oriented in different directions?

Answer 10

For support and protection.