Lung

General

Anatomy



Topic Completed: 1 August 2011

Minor changes: 9 August 2020

Copyright: 2003-2021, PathologyOutlines.com, Inc.

PubMed search: normal anatomy [title] pulmonary

Elliot Weisenberg, M.D.
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Cite this page: Weisenberg E. Anatomy. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungnontumoranatomy.html. Accessed October 25th, 2021.
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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Gross images

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Microscopic (histologic) images
Contributed by Grigory Demyashkin, M.D.
Lung, glandular stage

Lung, glandular stage

Lung, glandular stage; top: spine

Lung, glandular stage; top: spine

Top: spine; lower left: trachea and esophagus; center: lung, glandular stage

Top: spine; lower left: trachea and esophagus; center: lung, glandular stage

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