Lungs & Trachea

Question 1

Bronchopulmonary segments

Answer 1

1. Structurally separate; functionally independent units of lung tissue related to each segmental bronchus
2. Surrounded by connective tissue; has a separate pulmonary arterial supply
3. Pyramidal shape; apex towards hilum and base towards surface of lung
4. Separate respiratory units that can be removed w/o affecting others; if blocked only that segment will lose ventilation
5. Important in certain diseases as there won’t be spreading due to separation of each segment

Question 2

Bronchopulmonary segment names

Answer 2

RIGHT LUNG:
1. Superior lobe: Apical, POST, ANT
2. Middle lobe: Lat, Medial
3. Inferior lobe: Sup (apical), Med, ANT basal, Lat, POST basal

LEFT LUNG:
1. Superior lobe: Apical, POST, ANT, Sup, Inf. lingual
2. Inferior lobe: Sup (apical), Med, ANT basal, Lat, POST basal

Question 3

Features of bronchopulmonary segments

Answer 3

1. Separate pulmonary arterial supply
2. Own segmental bronchi
3. Surrounded by connective tissue continuous with visceral pleura
4. Pyramidal shape; apex towards hilum, base towards surface or lung
5. Can be removed w/o affecting the others

Question 4

Explain the anatomical basis of the aspiration of a foreign body

Answer 4

1. In supine; most likely to move towards right main bronchus
2. Right bronchus is shorter, broader, more vertical than left main bronchus
3. Carina is slightly elevated towards the left
4. In supine: deviates towards apical segment of right lower lobe due to gravity, as it is highest to arise from POST aspect of lung
5. In standing: it is gravity dependent
6. Enters right lung, gravitates towards the lowest segment of right lower lobe
7. i.e. POST basal segment of right lower lobe

Question 5

Mediastinum

Answer 5

1. Space b/w 2 parietal pleura
2. Boundaries:
   → ANT = sternum
   → POST = mediastinal pleura
   → LAT = vertebral column (12 thoracic vertebrae)
   → SUP = thoracic inlet
   → INF = diaphragm
3. Divided into 2 by a plane traveling @ sternal angle + intervertebral disc b/w T4 & T5
4. @ this plane contents:
   → Trachea bifurcates
   → Pulmonary trunk bifurcates just below
   → Ascending aorta ends
   → Arch of aorta
5. Divisions @ T4 level: Sup + Inf
6. Inf. mediastinum divided into 3 by fibrous pericardium: ANT, middle, POST

Question 6

Explain how a neck infection can spread into the mediastinum

Answer 6

1. 2 main fasciae of neck: prevertebral fascia + pretracheal fascia
2. Pretracheal fascia = ANT to trachea & blends with aortic arch
3. } Infections in front of trachea can spread through sup. mediastinum
4. Cannot enter middle mediastinum because of pericardium
5. Can spread down to ANT mediastinum as far as diaphragm