Human Anatomy: The Lungs

Lungs

• Lungs are soft, spongy, and elastic and would shrink to one-third or less in volume if the thoracic cavity were opened.
• Lungs are pink in children, but become dark and mottled with age due to the inhalation of dust particles that become trapped in the phagocytes of the lung.

Location and Structure

• The lungs are separated from each other by the heart and great vessels in the mediastinum.
• Each lung is conical, covered with visceral pleura, and suspended free in its own pleural cavity, attached to the mediastinum only by its root.

Borders

• The lungs have three borders: inferior, anterior, and posterior.
• The inferior border separates the base from the costal surface.
• The anterior border separates the costal surface from the medial surface.
• The posterior border separates the costal surface from the medial surface.

Parts of the Lung

• Each lung has a half-cone shape, with a base, apex, two surfaces, and three borders.
• The base sits on the diaphragm.
• The apex projects above rib I and into the root of the neck.
• The two surfaces are the costal surface and mediastinal surface.
• The costal surface lies adjacent to the ribs and intercostal spaces of the thoracic wall.
• The mediastinal surface lies against the mediastinum anteriorly and the vertebral column posteriorly and contains the comma-shaped hilum of the lung.

Lobes

• The right lung has three lobes: upper, middle, and lower.
• The left lung has two lobes: upper and lower.
• The lobes are separated by the horizontal and oblique fissures.

Hilum

• The hilum is the point where the bronchus, pulmonary artery, and pulmonary veins enter the lung.
• Each lung has a hilum.