What are the Lungs? Lobes, Segments and Hilum
Each lung is subdivided by fissures into lobes, and each lobe into bronchopulmonary segments — a modular anatomy that surgeons rely on to remove diseased tissue precisely. All the vessels, airways, and nerves reach the lung through a single gateway, the hilum.
The lungs are divided by fissures into lobes — three on the right, two on the left — and further into bronchopulmonary segments, with the hilum marking where the bronchus, vessels, and nerves enter each lung.
- •3 lobes: superior, middle, inferior
- •Oblique + horizontal fissures
- •~10 bronchopulmonary segments
- •Shorter, wider (liver sits below)
- •2 lobes: superior, inferior
- •Oblique fissure only
- •Lingula (middle-lobe equivalent)
- •Cardiac notch accommodates the heart
Step-by-step worked examples
A CT scan shows a mass in the right lung between the horizontal and oblique fissures. Which lobe is it in?
The right lung's 3 lobes are separated by 2 fissures The horizontal fissure separates the upper lobe from the middle lobe The oblique fissure separates the middle/upper from the lower lobe A mass between both fissures lies in the middle lobe.
Why does the left lung have a cardiac notch but the right lung does not?
The heart is tilted leftward in the thorax The left lung's anterior border indents to accommodate it This notch, plus the lingula, replaces the middle lobe seen on the right.
During lung transplant surgery, which structures must be reconnected at the hilum?
The hilum is the lung's root, where vessels and airway enter Structures include the main bronchus, pulmonary artery, and two pulmonary veins Plus bronchial vessels, lymphatics, and autonomic nerves All must be anastomosed for the transplant to function.
Flashcards
Quick quiz
Q1.How many bronchopulmonary segments does the right lung typically have?
Q2.What structure occupies the anterior indentation of the left lung?
Q3.The hilum of the lung is located on which surface?
Q4.Which fissure is unique to the right lung?
The full card deck, worked steps and AI-tutor support for “What are the Lungs? Lobes, Segments and Hilum” are in Notek — study by hand before your exam.
Common mistakes
Assuming both lungs have 3 lobes. — Correct: Only the right lung has 3; the left has 2 to make room for the heart.
Confusing the hilum with the fissures. — Correct: The hilum is where vessels/bronchus enter the lung; fissures divide the lung's surface into lobes.
Thinking the lingula is a separate lobe. — Correct: It's part of the left superior lobe, not an independent lobe.
Believing the right and left lungs are mirror images with identical segment counts. — Correct: They differ in lobes, fissures, and typically segment count (right ~10, left ~8-10 due to fusions).
FAQ
What are the lobes of the lungs?
The right lung has three lobes (superior, middle, inferior); the left lung has two (superior, inferior) to make room for the heart.
How many segments does each lung have?
The right lung typically has 10 bronchopulmonary segments; the left has about 8-10 due to some segments fusing.
What is the hilum of the lung?
The hilum is the region on each lung's mediastinal surface where the bronchus, pulmonary vessels, lymphatics, and nerves enter and exit.
Why does the left lung have fewer lobes than the right?
The heart's leftward position creates a cardiac notch, so the left lung is smaller with just two lobes instead of three.