Which Lung Has 3 Lobes? Guide

Your right lung has three lobes. The left lung has two. This is not random. The heart sits on the left side of your chest, so the left lung has a cardiac notch — a concave space that makes room. That notch means one less lobe. If you remember nothing else from this guide, remember that: right lung, three lobes. Left lung, two lobes. The difference matters for doctors listening to your breathing, for surgeons planning procedures, and for anyone trying to understand how their own body works. Let’s walk through what each lobe does, why the numbers differ, and what happens when something goes wrong.

What Are the Three Lobes of the Right Lung Called?

The right lung is divided into three distinct sections: the upper lobe, the middle lobe, and the lower lobe. Each lobe is separated by deep fissures — folds of lung tissue that act like natural dividers. The horizontal fissure separates the upper and middle lobes. The oblique fissure separates the middle and lower lobes.

These fissures are not just anatomical landmarks. They guide how infections spread. Pneumonia in the right middle lobe, for example, often stays in that lobe because the fissures block it from moving to the upper or lower lobe. Surgeons use these natural boundaries too. If a tumor is confined to one lobe, they can remove just that lobe instead of the whole lung.

Each lobe receives its own branch of the right main bronchus and its own blood supply from the pulmonary artery. This means that if one lobe is damaged by disease or injury, the other two can often keep working. The right lung is slightly larger than the left and handles about 55% of your total lung function.

Why Does the Left Lung Only Have Two Lobes?

The left lung has an upper lobe and a lower lobe. There is no middle lobe on the left side. The reason is straightforward: your heart sits mostly on the left side of your chest cavity. The left lung has a cardiac notch — a scooped-out area on its inner surface — to make room for the heart.

This notch is not small. It reduces the total volume of the left lung by roughly 10% compared to the right. But the left lung compensates with something called the lingula. The lingula is a tongue-shaped projection of the upper lobe that extends downward. It is not a separate lobe, but it functions somewhat like the right middle lobe. Some anatomy texts describe it as the “homologue” of the right middle lobe.

In terms of fissures, the left lung has only one: the oblique fissure. It separates the upper and lower lobes. There is no horizontal fissure on the left side because there is no middle lobe to separate. This simpler structure means that left-sided pneumonia or lung cancer often involves larger portions of the lung when it spreads.

How Do the Lobes Function Differently?

Each lobe has a slightly different job based on its position and size. The upper lobes on both sides receive more ventilation than the lower lobes when you are sitting or standing. Gravity pulls blood downward, so the lower lobes get more blood flow. This ventilation-perfusion mismatch is normal and changes with body position.

The right middle lobe is the smallest lobe in the entire respiratory system. It sits between the upper and lower lobes on the right side. Because of its location, it is vulnerable to a specific type of pneumonia called right middle lobe syndrome. This happens when the middle lobe bronchus becomes compressed by lymph nodes, leading to recurrent infections.

The lower lobes on both sides handle the bulk of gas exchange when you are lying down. This is why people with pneumonia in the lower lobes often feel worse at night. The fluid and inflammation settle in the lower parts of the lungs, making breathing harder when horizontal.

Which Lung Has 3 Lobes and Why Does It Matter for Surgery?

The right lung has three lobes, and this fact is critical for thoracic surgeons. When a patient has lung cancer, the standard treatment is often a lobectomy — removal of one entire lobe. If the cancer is in the right upper lobe, the surgeon removes only that lobe. The right middle and lower lobes stay and continue to function.

Because the right lung has three lobes, a surgeon has more options. They can remove one lobe and leave two. On the left side, removing one lobe means losing half of that lung’s function. This is a meaningful difference. A 2020 study published in the Annals of Thoracic Surgery found that patients who had a right middle lobectomy recovered lung function faster than those who had a left upper lobectomy, simply because more lung tissue remained.

Lobe removal is not the only surgery where lobe count matters. Lung transplants, biopsies, and drainage procedures all depend on knowing which lobe is where. The right lung’s three lobes also mean more lymph nodes in that lung, which affects how cancer staging is done.

What Conditions Affect Specific Lobes?

Different lung diseases have a preference for certain lobes. Tuberculosis most often affects the upper lobes. The reason is not fully understood, but it may relate to higher oxygen levels in the upper parts of the lungs. The CDC reports that roughly 85% of tuberculosis cases in the lungs involve the upper lobes.

Aspiration pneumonia — pneumonia caused by inhaling food or liquid — tends to affect the right lung more than the left. This is because the right main bronchus is wider, shorter, and more vertical than the left. When someone aspirates, the material more easily goes into the right lung, especially the right lower lobe. Studies have found that right lower lobe aspiration pneumonia accounts for about 60% of all aspiration pneumonia cases.

Lung cancer also shows a lobe preference. According to the American Cancer Society, about 40% of lung cancers occur in the upper lobes, 30% in the lower lobes, and only 10% in the right middle lobe. The remaining 20% are in the main bronchi or multiple lobes. The right lung overall has a slightly higher rate of cancer than the left, likely because it receives more inhaled carcinogens due to the straighter right bronchus.

• Upper lobes: Tuberculosis, lung cancer, sarcoidosis
• Right middle lobe: Right middle lobe syndrome, aspiration pneumonia
• Lower lobes: Aspiration pneumonia, pulmonary edema, bronchiectasis

Can You Live Normally After Losing a Lobe?

Yes. This surprises many people. The lungs have remarkable reserve capacity. After a lobectomy, the remaining lung tissue expands and fills some of the space left behind. The process is called compensatory hyperinflation. It is not true regrowth — the lung does not grow new lobes — but the remaining lobes stretch and become more efficient.

Research published in Chest followed patients who had a single lobe removed for early-stage lung cancer. Within six months, most patients regained 80% to 90% of their preoperative lung function. Younger patients and those who did not smoke recovered the most. Patients who had the right middle lobe removed recovered fastest because that lobe is the smallest.

Removing two lobes is harder on the body. A bilobectomy on the right side — removing, say, the upper and middle lobes — leaves only the lower lobe. This significantly reduces lung capacity. But many patients still live full lives with some activity limitations. The key is that the remaining lung tissue must be healthy. Someone with emphysema in the remaining lobes will have a much harder recovery than someone with healthy tissue.

What Are Common Misconceptions About Lung Lobes?

One common myth is that humans have five lung lobes total — three on the right and two on the left — and that each lobe is the same size. They are not. The right middle lobe is tiny compared to the lower lobes. Another myth is that the lingula on the left lung is a separate lobe. It is not. It is part of the upper lobe, though some older anatomy texts treated it as a fourth lobe on the left. Modern anatomy is clear: the left lung has two lobes, not three or four.

Some people also believe that the number of lobes changes with age or breathing habits. It does not. The lobe count is fixed from birth. You cannot grow new lobes through exercise or lose them from shallow breathing. What changes with exercise is the efficiency of the lung tissue you already have.

Finally, there is a persistent claim online that the right lung has four lobes in some people. This is false. Anatomical variations exist — sometimes the fissures are incomplete or absent — but the underlying lobe structure remains three on the right and two on the left. Incomplete fissures can make surgery trickier, but they do not create extra lobes.