Lung Segments: Total Count
The total number of bronchopulmonary segments in both lungs is 19: 10 segments in the right lung (3 in the upper lobe, 2 in the middle lobe, and 5 in the lower lobe) and 9 segments in the left lung (5 in the upper lobe and 4 in the lower lobe). 1
Anatomic Distribution
Right Lung (10 segments):
- Upper lobe: 3 segments
- Middle lobe: 2 segments
- Lower lobe: 5 segments
Left Lung (9 segments):
- Upper lobe: 5 segments (includes the lingula)
- Lower lobe: 4 segments
Clinical Relevance
This anatomic knowledge is fundamental for surgical planning, particularly when calculating predicted postoperative (PPO) lung function for lobectomy procedures. The anatomic method uses the formula: PPO FEV₁ = preoperative FEV₁ × (1 - y/z), where y represents the number of functional segments to be removed and z is the total number of functional segments (19) 1.
The asymmetry between right and left lungs (10 vs 9 segments) reflects the anatomic accommodation for the heart on the left side, which results in the left lung having one fewer segment than the right.
Understanding segmental anatomy is increasingly important as segmentectomy emerges as an alternative to more radical lobectomy, especially for early-stage lung cancer, allowing preservation of maximal pulmonary function 2. Modern three-dimensional CT imaging now allows detailed visualization of these segments and their anatomical variations, which is critical for surgical planning 2.