anatomy of the respiratory system

Question 1

Accessory muscles of inspiration

Answer 1

[Contract only during forceful inspiration]

• Sternocleidomastoid
• Scalenus

Question 2

Muscles of active expiration

Answer 2

[Contract only during active expiration]

• internal intercostal muscles
• Abdominal muscles

Question 3

Major muscles of inspiration

Answer 3

[Contract every inspiration; relaxation causes passive expiration]

• Diaphragm
• External intercostal muscles

[as-well as the sternum and ribs]

Question 4

Recess provides space for pulmonal expansion

Answer 4

As the volume of the lung changes with the thoracic cavity, the entire bronchial tree moves within the lung.
These structural movements are more pronounced in portions of the bronchial tree distant from the pulmonar hilum.

Question 5

Diaphragm

Answer 5

Major inspiratory muscle

Innervated by phrenic nerve

Question 6

Activated by intercostal nerves

Answer 6

External intercostal muscles

Question 7

flattening of the diaphragm

Answer 7

• 75 % of the enlargement of the thoracic cavity
  during quiet respiration is due to the
  contraction and flattening of the diaphragm.
• This expansion decreases the intrapleural
  pressure (down to 754).
• The lungs are drawn into this area of lower
  pressure.
• They expand.
• This increase in volume lowers the intra-
  alveolar pressure to a level below
  atmospheric pressure.
• By this difference, air enters the lungs.
• The action of accessory inspiratory muscles
  can further enlarge the thoracic cavity.