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Lung

General

Anatomy

Author: Elliot Weisenberg, M.D.

Last author update: 1 August 2011

Last staff update: 7 July 2022

Copyright: 2003-2024, PathologyOutlines.com, Inc.

PubMed search: normal anatomy [title] pulmonary

Table of Contents

Definition / general | Embryology | Diagrams / tables | Gross images | Microscopic (histologic) images

Cite this page: Weisenberg E. Anatomy. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungnontumoranatomy.html. Accessed December 25th, 2024.

Definition / general

Main function of lungs is gas exchange
Trachea divides into right and left mainstem bronchi
Right lung has 3 lobes (upper, middle and lower); left lung has 2 lobes (upper and lower) lobes; lingual is part of left upper lobe and is somewhat analogous to right middle lobe
Right bronchus is more vertical and in line with trachea than left; thus aspirated material tends to enter right lung
Each main bronchus divides into lobar bronchi, then into segmental bronchi
Lobar bronchi are usually called secondary bronchi and segmental bronchi are called tertiary bronchi, except in Japan, where they are called first order and second order, respectively
Bronchial walls contain cartilage and submucosal glands
Bronchioles are generally < 3 mm in diameter and lack cartilage and submucosal glands in their walls; their diameter varies
Bronchioles are generally divided into nonrespiratory bronchioles (all bronchioles proximal to respiratory bronchioles, including terminal bronchioles that are proximal to respiratory bronchioles) and respiratory bronchioles (airways with alveoli budding from their walls)
Alveoli are "dead ends" of airways; their walls are composed only of alveoli, where gas exchange takes place
Lung has double arterial supply - pulmonary and bronchial arteries that accompany airways; in general, diameter of airway is similar to that of accompanying pulmonary artery
Lungs are surrounded by visceral pleural membrane; inner chest cavity is lined by parietal pleural membrane; these membranes define pleural space, which normally has minimal volume
Regional lymph nodes: paratracheal, pre- and retrotracheal, aortic, subcarinal, periesophageal, inferior pulmonary ligament, hilar, peribronchial and intrapulmonary

Embryology

The lungs develop from the ventral wall of the foregut
The midline trachea develops two lateral outpouchings, the right and left lung buds
The lung buds extend into primitive thoracic mesenchyme that becomes bronchial cartilage and other connective tissue
The right lung bud develops three branches that become mainstem bronchi, the left lung bud develops two branches that become mainstem bronchi
The phases of lung development are embryonic (3 1/2 to 6 weeks), pseudoglandular (6 to 16 weeks), canalicular (16 to 28 weeks), saccular (28 to 36 weeks) and alveolar (36 weeks to term)

Diagrams / tables

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