What are the main functions and basic characteristics of the lungs?

The lungs are the primary organs of respiration, responsible for gas exchange between air and blood. They are conical, spongy organs located on either side of the mediastinum, with the right lung typically weighing about 700 g and having 3 lobes, and the left lung weighing about 650 g with 2 lobes.

How do the lobes and fissures differ between the right and left lungs?

The right lung has 3 lobes (superior, middle, inferior) separated by two fissures: an oblique fissure and a horizontal fissure. The left lung has 2 lobes (superior, inferior) separated by only an oblique fissure.

What structures are found in the hilum and lung root?

The lung root connects the lung to the mediastinum and contains key structures entering and exiting at the hilum, including bronchi (2 in the right, 1 in the left), pulmonary artery, 2 pulmonary veins, bronchial arteries and veins, lymphatics, and nerve plexuses.

How is the blood supply to the lungs organized?

The lungs have a dual blood supply: bronchial arteries provide nutritional blood, with branches from the descending aorta or intercostal arteries, while pulmonary arteries carry deoxygenated blood for gas exchange, following the bronchial tree. Venous drainage includes bronchial veins to the azygos system and pulmonary veins for oxygenated blood.

What is the nerve supply to the lungs and its effects?

The lungs receive autonomic innervation: parasympathetic fibers from the vagus nerve cause bronchoconstriction, vasodilation, and increased secretions, while sympathetic fibers from T2–T5 spinal segments cause bronchodilation, vasoconstriction, and decreased secretions.

What are the key surface markings and clinical relevance of lung anatomy?

Surface markings help locate lung structures: the anterior border has a cardiac notch on the left at the 4th–5th intercostal space, the inferior border extends to the 6th rib at the midclavicular line and 10th rib posteriorly, and fissures are used for auscultation. Clinically, incomplete fissures can lead to air leaks after surgery.

How does lymphatic drainage of the lungs relate to disease spread?

Lymphatic drainage occurs via superficial and deep plexuses that converge at hilar nodes, then to tracheobronchial and bronchomediastinal nodes, eventually reaching the thoracic duct. This pathway is clinically significant because lung cancer often metastasizes through these lymphatics.

Lungs Anatomy – Lobes, Fissures, Hilum & Blood Supply

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