What is Lung Lobar and Segmental Anatomy?
Lung lobar and segmental anatomy describes how each lung is divided by fissures into lobes, and each lobe is further subdivided into bronchopulmonary segments. This hierarchical organization matters clinically for localizing disease and planning surgical resections.
The right lung has 3 lobes (superior, middle, inferior) separated by an oblique and a horizontal fissure, while the left lung has 2 lobes (superior, inferior) separated by only an oblique fissure; each lobe subdivides into bronchopulmonary segments, each supplied by its own segmental bronchus.
- •Superior lobe
- •Middle lobe
- •Inferior lobe
- •Oblique + horizontal fissures
- •~10 bronchopulmonary segments
- •Superior lobe (with lingula)
- •Inferior lobe
- •Only an oblique fissure
- •No middle lobe — lingula is its equivalent
- •~8-9 bronchopulmonary segments
Step-by-step worked examples
A patient has a pneumonia isolated to the right middle lobe. Which fissures border this lobe?
The right middle lobe sits between the horizontal (minor) fissure above and the oblique (major) fissure below The horizontal fissure separates it from the superior lobe The oblique fissure separates it from the inferior lobe Because the left lung has no horizontal fissure, it has no anatomical middle lobe
A surgeon needs to resect a single bronchopulmonary segment rather than a whole lobe. Why is this possible?
Each bronchopulmonary segment has its own segmental (tertiary) bronchus Each segment has its own independent artery supply Segments are separated by connective tissue septa with only shared venous drainage This independence allows a segmentectomy without removing the entire lobe
Why does the left lung have fewer lobes and segments than the right lung?
The heart and pericardium occupy space in the left thoracic cavity (cardiac notch) The left lung compensates by having only 2 lobes instead of 3 The lingula on the left lung is the developmental/functional equivalent of the right middle lobe Left lung typically has 8-9 segments versus about 10 on the right
Flashcards
Quick quiz
Q1.How many lobes does the right lung have?
Q2.Which fissure is unique to the right lung?
Q3.What is the smallest surgically resectable functional unit of the lung?
Q4.Approximately how many bronchopulmonary segments does the right lung have?
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Common mistakes
Both lungs have 3 lobes. — Correct: Only the right lung has 3 lobes; the left lung has 2, due to space taken by the heart.
The left lung has a middle lobe. — Correct: The left lung has no middle lobe — the lingula is its functional counterpart, part of the superior lobe.
Bronchopulmonary segments share bronchi with neighboring segments. — Correct: Each bronchopulmonary segment has its own dedicated segmental (tertiary) bronchus and artery.
Lobes and segments are the same structure at different scales, with no clinical difference. — Correct: Segments are clinically distinct because they can be surgically removed individually (segmentectomy) without sacrificing the whole lobe.
FAQ
What is lung lobar and segmental anatomy?
It's the hierarchical division of each lung — first into lobes by fissures, then into bronchopulmonary segments each with its own bronchus and artery.
What is the formula for how many lobes each lung has?
Right lung = 3 lobes (superior, middle, inferior); left lung = 2 lobes (superior, inferior) plus the lingula.
What are examples of bronchopulmonary segments?
The right lung's apical, posterior, and anterior segments of the superior lobe are classic examples, each independently resectable.
How is lung segmental anatomy used clinically?
Radiologists localize pneumonia or tumors to a specific segment, and surgeons can remove just that segment (segmentectomy) instead of an entire lobe.