Respiratory system anatomy

Question 1

At what level does the trachea originate?

Answer 1

C6 (larynx C3 - C6)

Question 2

At what level is the tracheal bifurcation (carina)

Answer 2

T5 - T6

Question 3

How long is the trachea in adults and what is its length above the suprasternal notch?

Answer 3

15cm long
5cm of trachea above the suprasternal notch
8 cm of trachea above the suprasternal notch when neck is in full extension

Question 4

What is the diameter of the trachea?

Answer 4

Its about the width of the base of the patients index finger

Question 5

What makes up the anterior and posterior aspects of the trachea

Answer 5

Anteriorly - C-shaped cartilage rings

Posteriorly - Trachealis muscle

Question 6

Which tracheal rings are covered by the thyroid isthmus?

Answer 6

2nd to the 4th tracheal ring (percutaneous tracheostomy tube sited in the space between the 2nd and 3rd tracheal ring)

Question 7

What type of cartilaginous rings are contained within the bronchi?

Answer 7

Complete cartilaginous rings

Question 8

Describe the right main bronchus compared to the left main bronchus

Answer 8

Shorter wider and more vertically positioned

Question 9

How far from the origin of the bronchi do the left and right upper lobe bronchi originate from the left main bronchi and right main bronchi respectively

Answer 9

Right upper lobe bronchi originates 2.5 cmm from the carina

The left upper lobe bronchi originates > 5 cm from carina

Clinically implications for one lung intubation/ventilation

Question 10

How many lobes in the right and left lung?

Answer 10

Right lung: 3 lobes (upper, middle, lower)

Left lung: 2 lobes plus lingula

Question 11

During which common procedures may the pleural cavity be inadvertently opened to cause a pneumothorax?

Answer 11

CVL insertion
Supraclavicular brachial plexus block
Intercostal nerve block
Surgery on the kidney/adrenal gland

Question 12

How many functionally separate bronchopulmonary segments does each main bronchus divide into and what is the clinical relevance of these bronchopulmonary segments?

Answer 12

10
Relevant for the surgeon in lung resection surgery as each bronchopulmonary segment has its own bronchus, blood supply and distinct lung parenchyma.

Question 13

Name the bronchopulmonary segments

Answer 13

Both lungs

Upper lobe

• Apical
• Posterior
• Anterior

Middle Lobe

• Medial (in the left lung this is the superior lingular)
• lateral (in the left lung this is inferior lingula)

Lower lobe

• Apical
• Medial basal
• Lateral basal
• Posterior basal
• Anterior basal

Question 14

Which lung segment is most commonly affected by aspiration during anaesthesia

Answer 14

Right lower lobe apical segment is the first segmental bronchus to arise posteriorly and is the most commonly affected in the supine patient.

Question 15

What is a primary lung lobule?

Answer 15

Each bronchiole with its further subdivision (into respiratory bronchioles, alveolar ducts and alveoli) is called a primary lung lobule

Question 16

What is contained within the bronchiolar wall

Answer 16

No cartilage
Smooth muscle
ciliated cuboidal epithelium

Question 17

Describe the cells in the alveoli

Answer 17

Type 1 pneumocytes - specialised squamous epithelium seperated from surounding endothelium of the blood capillary network by the thin basement membrane

Type 2 pneumocytes - produce surfactant to counter surface tension and atelectasis

Question 18

Define and describe the mediastinum

Answer 18

The space between the two plural cavities consisting of 4 compartments

SUPERIOR MEDIASTINUM

Superior mediastinum

INFERIOR MEDIASTINUM
Anterior inferior mediastinum (mass here is significant anaesthetic risk due to potential compression of heart, great vessels, major airways especially when muscle tone is lost in anaesthesia)

Posterior inferior mediastinum

Middle inferior mediastinum (containing the pericardium)

Question 19

Name the spinal levels that permit function of the diaphragm

Answer 19

C3 4 and 5 keep the diaphragm alive –> via the phrenic nerve

Question 20

Which muscles contributes to the lower oesophageal sphincter mechanism?

Answer 20

Diaphragm - mechanism disrupted in patients with a hiatus hernia –> GORD - risk for aspiration

Question 21

What is the range of diaphragm movement?

Answer 21

1.5 cm during quiet breathing

13 cm during deep breathing

Question 22

When can the phrenic nerve be damaged?

Answer 22

During cardiac surgery

Question 23

What effect does a damaged phrenic nerve have on the diaphragm

Answer 23

Paradoxical movement of the diaphragm on the affected side during inspiration diagnosed by fluoroscopy

Question 24

What conditions may limit diaphragm movement

Answer 24

1. Pregnancy (Fetus)
2. Obesity (Fat)
3. Ascites (Fluid)
4. Large abdominal tumours (Fucking cancer)
5. Pneumoperitoneum (Flatus) – Diaphragmatic impairment caused by gastric distension following BVM can be a particular problem in children

Question 25

Describe the orientation and function of the external intercostal muscles

Answer 25

Slope downward and forward –> contraction leads toupward and outward movement increasing the AP diameter of the thorax

Question 26

Describe the orientation and function of the internal intercostals

Answer 26

Slope downward and backward –> contraction leads to downward and inward movement of the ribs to decrease the volume of the thoracic cavity during forced expiration.

Question 27

What is the function of the innermost intercostal muscles?

Answer 27

Link ribs together and stabilize chest wall

Question 28

What is the nerve supply to the intercostal muscles and what is the effects of intercostal nerve blocks (Spinal/epidural anaesthesia for abdominal surgery) on respiration

Answer 28

Intercostal nerves T1 -T11

Minimal effects on respiration as the diaphragm is the more important muscle of respiration

Question 29

Name the four accessory respiratory muscles

Answer 29

Scalene
Sternomastoids
Alae nasi
Small muscles of the head and neck

Question 30

Name the scalene muscles and their function

Answer 30

Medial and anterior Scalene muscles - elevate the first 2 ribs

Question 31

Sternocleidomastoid muscle function?

Answer 31

Elevate the sternum (multiple movements of the head - flex, rotate)

Question 32

Alae nasi function?

Answer 32

Flare nostrils

Question 33

Small muscles of head and neck function?

Answer 33

‘Head bobbing’ in infants

Question 34

What is the ideal placement of the ETT

Answer 34

cuff inflated just beyond the vocal cords in the immediate sub-glottic area with the tip of the tube midway between the vocal cords and the carina.

Males - 23 cm at the lips
Females - 21 cm at the lips

Question 35

ETT too far –> which areas of the lung are prone to collapse

Answer 35

The left lung and the right upper lobe

Question 36

On a CXR which spinous process is visible directly between the clavicles

Answer 36

T4

Question 37

What is the correct site for emergency needle thoracocentesis in tension pneumothorax

Answer 37

2nd ICS MCL

Question 38

What is the correct site for the insertion of an ICD

Answer 38

5th intercostal space MAL in the safe triangle (Bordered by lat, pec major and axilla)

Question 39

What are the vertebral levels for the diaphragmatic hiatuses?

Answer 39

The word vena cava has 8 letters - T8

Oesophagus has 10 letters - T10

Aortic hiatus has 12 letters - T12

Question 40

Summarizes the course of the left and right phrenic nerve

Answer 40

Originates: C3, C4, C5

Emerge and pass over the anterior scalene muscles
Descend through the thorax over the heart
Left through aortic hiatus but motor innervation to superior and inferior surfaces
Right goes through vena cava hiatus