Ventilation and Perfusion

Question 1

How is the spine divided?

Answer 1

The spine is divided into cervical, thoracic, and lumber sections:
- C1 - 7
- T1 - 12
- L1 - 5

Question 2

True Ribs

Answer 2

• 1 - 7, the ribs are attached directly, distally to the sternum by cartilage

Question 3

False ribs

Answer 3

• ribs 8 - 10
• distal attachment via cartilage to superior neighbour (thoracic vertebra rather than sternum)

Question 4

Floating ribs

Answer 4

• 11 - 12
• no distal attachment to sternum

Question 5

What effect on diameter does movement of the ribs have?

Answer 5

• increased in transverse and anteroposterior diameter
• thorax gets deeper and wider

Question 6

Muscles used in inspiration (contraction along zone of apposition)

Answer 6

• external intercostal muscles contract
• diaphragm contracts (primary)
• sternocleidomastoid is accessory muscle of inspiration
• scalene muscles are accessory muscles that elevate ribs during forced inspiration
• abdomen becomes compressed, increasing in lateral diameter, pushing out lower ribs as diaphragm contracts and pulls downwards

Question 7

Muscles used on expiration

Answer 7

• internal intercostal muscles contract
• abdominal muscles contract

Question 8

What is the pleura

Answer 8

• membranes forming a continuous cover of the lung and inside chest wall

Question 9

Function of pleural membranes

Answer 9

• lubricates organs to minimise friction

Question 10

What is the zone of apposition? and relation to inspiration

Answer 10

• the space where the diaphragm is directly attached to the lower ribcage (this is where contraction occurs during inspiration)

Question 11

Explain how the scalene muscles and sternocleidomastoid are used during inspiration

Answer 11

scalene: helps elevate first and second ribs to increase intrathoracic volume
sternocleidomastoid: also elevates ribcage