Respiration

Question 1

Muscles of normal inspiration

Answer 1

• Diaphragm

- External intercostal muscles

Question 2

Muscles of normal expiration

Answer 2

• Passive

Question 3

Muscles of forced inspiration

Answer 3

• Scalene

- Sternocleidomastoid

Question 4

Muscles of forced expiration

Answer 4

• Internal intercostal muscles

- Abdominal muscles (rectus abdominis, external/internal obliques and transverses abdominis)

Question 5

Diaphragm function

Answer 5

Main muscle of respiration

- Forms boundary between thoracic and abdominal cavities

Question 6

Diaphragm structure

Answer 6

• Left and right domes
• Central tendon
• Left and right crus
• Hiatuses
• Superior surface covered by parietal pleura

Question 7

Right dome vs left dome

Answer 7

Right is more superior
- accommodate heart and liver

L1-2 on left
L1-3 on right

Question 8

Diaphragm attachments (4)

Answer 8

• Central (membranous) tendon: fibrous pericardium
• Ribs 7-12 costal cartilages
• Xiphoid process
• L1-3 vertebrae

Question 9

Diaphragm hiatuses

Answer 9

• T8: vena cava
• T10: oesophagus, vagal nerves
• T12: aorta, thoracic duct, azygous vein

Question 10

Innervation

Answer 10

• Phrenic nerves: motor and sensory

- Intercostal nerves (T5-12): sensory to peripheral

Question 11

Phrenic nerve: nerve roots

Answer 11

Anterior rami of C3,4 and 5

Question 12

Phrenic nerves: sensory function

Answer 12

• Central part of diaphragm
• Pericardium
• Mediastinal parietal pleura

Question 13

Phrenic nerves: anatomical course

Answer 13

• Arises: lateral border of anterior scalene
• Between subclavian vessels
• Enters thoracic inlet
• Descends anterior to lung root
• Along pericardium
• Pierces diaphragm and innervates inferior surface

Question 14

Normal radiographic position of the diaphragm

Answer 14

• “Take a deep breath and hold it for several seconds”

- Flattens diaphragm