Bronchopulmonary segmental anatomy

Last revised by Craig Hacking on 27 Mar 2024

Bronchopulmonary segmental anatomy describes the division of the lungs into segments based on the tertiary or segmental bronchi.

The trachea divides at the carina forming the left and right main stem bronchi which enter the lung substance to divide further. This initial division is into secondary or lobar bronchi, but subsequent divisions give rise to smaller and smaller bronchi and bronchioles until the smallest bronchioles connect to the innumerable alveoli.

Each segment has its own pulmonary arterial branch and thus, the bronchopulmonary segment is a portion of lung supplied by its own bronchus and artery. Each segment is functionally and anatomically discrete allowing a single segment to be surgically resected without affecting its neighboring segments.

There is some form of segmental symmetry between the right and left lungs, even though the left lung is smaller and only contains two lobes. In general, each lung has 10 segments: the upper lobes contain 3 segments, the middle lobe / lingula 2 and the lower lobes 5. Bilaterally, the upper lobes have apical, posterior and anterior segments and the lower lobes superior (apical) and 4 basal segments (anterior, medial, posterior and lateral). With this basic symmetric anatomy shared between the lungs, there are a few differences that can be described:

The right lung is subdivided into three lobes with ten segments. The notation in brackets refers to the Boyden classification of bronchi.

The left lung is subdivided into two lobes and thereby, into eight segments. The notation in brackets refers to the Boyden classification of bronchi.

Useful mnemonic to remember the bronchopulmonary segments are:

  • A PALM Seed Makes Another Little Palm (right lung)
  • ASIA ALPS (left lung)

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