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Bronchopulmonary segmental anatomy

Dr Frank Gaillard and Dr Jeremy Jones et al.

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

Gross anatomy

The trachea divides at the carina where the left and right main stem bronchi are formed and 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 meaning that a single segment can be surgically removed without affecting its neighbours.

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 3, 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 symmetric anatomy shared between the lungs, there are a few differences that can be described:

  • the middle lobe has 2 segments, medial and lateral (easy to remember - middle lobe, medial and lateral).
  • the lingula on the left is part of the left upper lobe and is the equivalent of the middle lobe on the right, and hence has 2 segments, but in this case it is divided into superior and inferior.
  • there are 2 parts of the left lung which are 2 segments joined as 1:
    • left upper lobe apicoposterior segment
    • left lower anteromedial

Right lung

The right lung is subdivided into three lobes with ten segments:

Left lung

The left lung is subdivided into two lobes and thereby, into eight segments:

Variant anatomy

Related articles

Thoracic anatomy

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