Respiratory Physiology Lecture 1.5: Respiratory Muscles

Question 1

Muscles of inspiration?

Answer 1

• Sternocleidomastoid Scalenes
• External intercostals
• Parasternal intercostals
• Diaphragm

Question 2

Muscles of expiration

Answer 2

• Internal intercostals
• External abdominal oblique
• Internal abdominal oblique
• Transversus abdominis
• Rectus abdominis

Question 3

What does the diaphragm separate?

Answer 3

separates the thoracic and abdominal cavities

Question 4

location of external intercostals

Answer 4

between ribs

Question 5

location of parasternal intercostals

Answer 5

between the ribs but close to the sternum

Question 6

Diaphragm

Answer 6

Inspiratory pump muscle

a dome-shaped muscle which flattens during contraction (INS), abdominal contents are forced down and forward and rib cage is widened.

Question 7

What happens to the volume of the thorax with diaphragm contraction?

Answer 7

Increase in volume of the thorax

Question 8

External intercostal muscles

Answer 8

Inspiratory pump muscles

contract and pull ribs upward increasing the lateral volume of the thorax

Question 9

What sort of motion do the external intercostals have?

Answer 9

Bucket handle motion

Question 10

Parasternal intercostal muscles

Answer 10

Inspiratory pump muscles

contract and pull sternum forward, increasing anterior posterior dimension of the rib cage

Question 11

What sort of motion is the parasternal intercostal muscles?

Answer 11

pump handle motion

Question 12

What are the abdominal muscles involved in respiration?

Answer 12

abdominals

• External oblique
• internal oblique
• transversus abdominis
• rectus abdominis

Question 13

abdominal muscle activity

Answer 13

Expiratory pump muscles

Passive during inspiration and not active during expiration at rest but are recruiting in expiration when really making an effort to breathe in and out

• Relaxed at rest. Involved in other physiological functions (Coughing, vomiting, defecation, posture)
• Deeper, faster breathing requires active contraction of abdominal & internal intercostal muscles to return the lung to its resting position (Exercise)

Question 14

Internal intercostal muscles activity

Answer 14

Expiratory pump muscles

• Relaxed at rest
• During exercise, internal intercostal muscles pull rib cage down, reducing the thoracic volume

Question 15

What are the accessory inspiratory muscles?

Answer 15

• scalenes
• sternocleidomastoids

Question 16

scalene and stercleidomastoids muscles activity

Answer 16

Scalenes → elevate upper ribs

Sternocleidomastoids → raise the sternum

Scalenes and sternocleidomastoids contribute little to quiet breathing (At rest)

They contract vigorously during exercise or forced respiration