Thorax 2 - Tracheobronchial tree

Question 1

what is the tracheobronchial tree?

Answer 1

the system of the trachea, bronchi and bronchioles/airways that allow the passage of air into the lungs for gas exchange

Question 2

what are the contents of the tracheobronchial tree in order (from the trachea to alveoli)?

Answer 2

trachea
primary/main bronchi
secondary bronchi
tertiary bronchi
terminal bronchioles
respiratory bronchioles
acinus - clusters of alveoli
alveoli sacs - lined with ducts

Question 3

what does the branching of bronchi into bronchioles allow for?

Answer 3

allows for more precise control of airflow and distribution of air throughout the lungs

Question 4

the respiratory system consists of a CONDUCTING part & RESPIRATORY part - what does each part do?

Answer 4

conducting part = conducts air from the outside into the lungs

respiratory part = where gas exchange occurs (in the alveoli with the bloodstream)

Question 5

where does the trachea originate? at what vertebral level?

Answer 5

originates at the lower border of the cricoid cartilage - C6/7

Question 6

where does the trachea end? at what vertebral level?

Answer 6

at the carina - T4/5

Question 7

what is the carina?

Answer 7

a cartilaginous ridge at the level of T4/5 - marks the end of the trachea & bifurcation into the right and left main bronchi

Question 8

what happens at the carina?

Answer 8

trachea ends & bifurcates into the right and left main bronchi

Question 9

what is the shape of the hyaline cartilage rings in the trachea?

Answer 9

hyaline cartilage rings are C-shaped with an open posterior portion (covered by trachealis smooth muscle)

Question 10

why is the posterior portion of the tracheal cartilage rings open?

Answer 10

prevents pressure on the oesophagus which lies immediately posterior to the trachea

Question 11

why is the C-shape of the tracheal hyaline cartilage rings important?

Answer 11

shape maintains the patency of the trachea - prevents it from collapsing whilst balancing structural stability & flexibility

Question 12

what fills the open posterior portion of the tracheal cartilage rings?

Answer 12

smooth muscle called the trachealis muscle

Question 13

what is the purpose of the trachealis muscle?

Answer 13

• allows flexibility
• prevents compression of the oesophagus
• adjusts the tracheal diameter during coughing/ forced expiration

Question 14

what is the anatomical significance of the carina during bronchoscopy?

Answer 14

appears as a sharp distinct ridge at the tracheal bifurcation (T4/5 level - also at the sternal angle & level of 2nd rib)

Question 15

how does the right main bronchus differ from the left main bronchus in terms of structure?

Answer 15

right main bronchus is wider, shorter & more vertical

left main bronchus is narrower, more horizontal & appears more as a branching structure

Question 16

why are foreign objects more likely to enter the right main bronchus in adults?

Answer 16

right main bronchus is wider, shorter & more vertical - is more of a direct continuation of the trachea and thus more prone to foreign objects entering

Question 17

what are the characteristics of an abnormal carina during bronchoscopy? what can this indicate?

Answer 17

abnormal carina is blunted, widened or distorted maybe with underlying bumps - can indicate metastatic cancer spread to the inferior tracheobronchial lymph nodes

Question 18

what is the clinical importance of the inferior tracheobronchial lymph nodes in relation to the carina?

Answer 18

enlargement of the tracheobronchial LNs causes widening/distortion of the carina - indicates metastatic cancer

Question 19

in children, how do foreign objects tend to distribute between the right and left bronchi compared to adults?

Answer 19

in children = tend to distribute equally between both bronchi

in adults = more likely to enter the right main bronchus

Question 20

what are the secondary bronchi? how do they differ between the right & left lungs?

Answer 20

secondary bronchi - branches of the primary/main bronchi

right lung has 3 secondary bronchi (corresponding to its 3 lobes)

left lung has 2 secondary bronchi (corresponding to its 2 lobes)

Question 21

how many tertiary bronchi are there per lung? what is their function?

Answer 21

right lung - approx. 10
left lung - approx. 8-10

ensure efficient airflow to all parts of the lungs

Question 22

what structural change occurs in the walls of terminal bronchioles compared to earlier bronchi?

Answer 22

terminal bronchioles no longer have hyaline cartilage in their walls - makes them more susceptible to collapse

Question 23

role of respiratory bronchioles in the bronchial tree?

Answer 23

lead to the respiratory portion of the lungs and terminate in clusters of alveoli (acinus) - facilitate gas exchange.

Question 24

what is the primary function of alveoli in the respiratory system?

Answer 24

alveoli are the sites of gas exchange (O₂ and CO₂) during breathing - maximise surface area for efficient gas exchange between air & blood

Question 25

what happens to the structure of the bronchial tree as it progresses from tertiary bronchi to terminal bronchioles?

Answer 25

airways become smaller & hyaline cartilage isn’t present in the walls - makes them more susceptible to collapse

Question 26

what arteries supply the upper two-thirds of the trachea? where do they arise from?

Answer 26

inferior thyroid arteries - branch from the subclavian artery

Question 27

what arteries supply the lower one-third of the trachea? where do they arise from?

Answer 27

bronchial arteries - branches of the thoracic aorta (sometimes arise from the internal thoracic artery instead)

Question 28

what is an anatomical variation in the origin of the bronchial artery?

Answer 28

the bronchial artery may arise from the internal thoracic artery instead of the thoracic aorta

Question 29

which lymph nodes are involved in the lymphatic drainage of the tracheobronchial tree? (3)

Answer 29

pretracheal LNs
paratracheal LNs
deep cervical LNs

Question 30

what nerves provide sensory innervation to the trachea?

Answer 30

the vagus nerve & recurrent laryngeal nerve (a branch of the vagus nerve)

Question 31

what cranial nerve number is the vagus nerve?

Answer 31

10

Question 32

what is the motor nerve supply to the trachealis muscle? what is its function?

Answer 32

supplied by sympathetic nerves - regulate tracheal diameter

Question 33

how is the upper 2/3 of the trachea drained?

Answer 33

upper 2/3 is drained by inferior thyroid veins - to the superior vena cava

Question 34

what is the venous drainage pathway for the lower two-thirds of the trachea and bronchial tree on the RIGHT side?

Answer 34

bronchial veins > azygos vein > superior vena cava

Question 35

what is the venous drainage pathway for the lower two-thirds of the trachea and bronchial tree on the LEFT side?

Answer 35

bronchial veins > accessory hemiazygos vein > hemiazygos vein > crosses midline & into azygos vein > superior vena cava

Question 36

what is the significance of the recurrent laryngeal nerve in tracheal innervation?

Answer 36

it’s a branch of the vagus nerve - provides sensory innervation to the trachea

Question 37

how does the venous drainage of the trachea and bronchial tree reflect its arterial supply?

Answer 37

venous drainage follows a similar pattern to the arterial supply:

upper 2/3s of the trachea are supplied by the inferior thyroid arteries & drained by the inferior thyroid veins

lower 1/3 of the trachea is supplied by the bronchial arteries & drained by the bronchial veins - differing venous drainage on the left and right sides

Question 38

how does venous drainage of the lower 1/3 of the trachea differ between the left & right sides?

Answer 38

left side: bronchial veins > accessory hemiazygos vein > hemiazygos vein > azygos vein > superior vena cava

right side: bronchial vein > azygos vein > superior vena cava

Question 39

at which vertebral level does the trachea terminate and the carina begin?
A. T2/T3
B. T4/T5
C. T6/T7
D. T8/T9

Answer 39

B: T4/5

Question 40

which of the following is true about the right main bronchus compared to the left?
A. It is narrower and more horizontal.
B. It is wider, shorter, and more vertical.
C. It is longer and less vertical.
D. It is less likely to be obstructed by foreign objects.

Answer 40

B: it’s wider, shorter, and more vertical (more likely to be obstructed by foreign objects)

Question 41

which arteries supply the lower one-third of the trachea?
A. Bronchial arteries
B. Internal thoracic arteries
C. Inferior thyroid arteries
D. Subclavian arteries

Answer 41

A: bronchial arteries

Question 42

during bronchoscopy, what finding would most likely indicate metastatic cancer in the inferior tracheobronchial lymph nodes?
A. A sharp, well-defined carina
B. A blunted, widened carina
C. A normal, thin carina
D. A carina with no visible ridges

Answer 42

B: a blunted, widened carina

Question 43

which of the following is true about the venous drainage of the tracheobronchial tree?
A. The upper two-thirds of the trachea are drained by the bronchial veins.
B. The left bronchial veins drain directly into the superior vena cava.
C. The right bronchial veins drain into the azygos vein.
D. The inferior thyroid veins drain the lower one-third of the trachea.

Answer 43

C: the right bronchial veins drain into the azygos vein

(RIGHT bronchial veins > azygos vein > SVC)

Question 44

what is the significance of the disappearance of hyaline cartilage in terminal bronchioles?
A. It increases resistance to airflow.
B. It makes the airways less susceptible to collapse.
C. It increases susceptibility to collapse.
D. It enhances gas exchange efficiency.

Answer 44

C: it increases susceptibility to collapse

Question 45

which of the following nerves provides motor innervation to the trachealis muscle?
A. Vagus nerve
B. Recurrent laryngeal nerve
C. Sympathetic nerves
D. Phrenic nerve

Answer 45

C: sympathetic nerves (allows control over tracheal diameter)

Question 46

which of the following is true about the lymphatic drainage of the tracheobronchial tree?
A. Lymph fluid drains directly into the thoracic duct.
B. The deep cervical lymph nodes are not involved in tracheobronchial drainage.
C. Pretracheal and paratracheal lymph nodes filter lymph from the tracheobronchial tree.
D. Lymphatic drainage is primarily through the bronchial lymphatic vessels.

Answer 46

C: pretracheal and paratracheal lymph nodes filter lymph from the tracheobronchial tree (and deep cervical LNs)

Question 47

during a surgical procedure, a surgeon notices an abnormality in the venous drainage of the left bronchial tree. Which of the following pathways correctly describes the venous drainage of the left bronchial tree?
A. Bronchial veins → azygos vein → superior vena cava
B. Bronchial veins → accessory hemiazygos vein → hemiazygos vein → azygos vein → superior vena cava
C. Bronchial veins → inferior thyroid veins → brachiocephalic vein
D. Bronchial veins → internal thoracic vein → subclavian vein

Answer 47

B: bronchial veins → accessory hemiazygos vein → hemiazygos vein → azygos vein → superior vena cava

Question 48

A patient undergoes surgery for a tracheal tumour located in the lower one-third of the trachea. Which artery is most likely responsible for supplying blood to this region, and what is its origin?
A. Inferior thyroid artery – branch of the subclavian artery
B. Superior thyroid artery – branch of the external carotid artery
C. Internal thoracic artery – branch of the subclavian artery
D. Bronchial artery – branch of the thoracic aorta

Answer 48

D: bronchial artery – branch of the thoracic aorta