Lung Lobes

What are the Lobes of the Lungs

The two human lungs are divided into multiple smaller sections by fissures. These sections are called the lobes of the lungs ^[1].

How Many Lobes are There in the Lungs

The number of lobes varies between the right and left lungs in a normal human being:

How Many Lobes Does the Right Lung Have

The right lung has three lobes, namely, the superior (upper), middle and inferior (lower) lobes ^[2].

How Many Lobes Does the Left Lung Have

Unlike the right lung, there are only two lobes in the left lung: the superior (upper) and inferior (lower) lung lobes ^[3].

Why does the right lung have three lobes and the left lung has two

The left lung is a little smaller than the right lung because it has to make space for the heart (the cardiac notch) in the left side of the thoracic cavity. As a result, the right lung is larger, having three lobes, while the left one only has two ^[4].

Lung Lobe Anatomy

The lobes are further separated into smaller segments, with the right lung having 10 segments and the left lung having 9 ^[2].

Lung Lobes

Segments of the Lobes

In the Right Lung

Right superior (upper) lobe

• Apical segment
• Posterior segment
• Anterior segment

(Right) middle lobe

• Lateral segment
• Medial segment

Right inferior (lower) lobe

• Superior segment
• Medial basal segment
• Anterior basal segment
• Lateral basal segment
• Posterior basal segment ^[5]

In the Left Lung

Although the left lung has only two lobes, there is an evident projection from the upper lobe, referred to as lingula which has two segments ^[6].

Left superior (upper) lobe

• Apicoposterior segment
• Anterior segment

Lingula:

• Superior lingular segment
• Inferior lingular segment

Left inferior (lower) lobe

• Superior segment
• Anteromedial segment
• Lateral segment
• Posterior segment ^[7]

The lingula serves as the equivalent to the right lung’s middle lobe in the left lung ^[8].

Lung Fissures

Oblique Fissures: Separates the superior or upper lobe from the lower lobes of both lungs ^[9].

Horizontal Fissure: Present only in the right lung, separates the middle lobe from the upper and lower right lung lobes ^[1].

Air Supply to the Lung Lobes

After entering the lungs, the right bronchus divides into three lobar bronchi, while the left bronchus divides into two lobar bronchi ^[10] – one for each of the lung lobes. These lobar bronchi then divide into tertiary or segmental bronchi. There are 10 tertiary bronchi in the right lung and 9 in the left, so each of the lung segments is supplied by one of these bronchial branches ^[11]. The tertiary bronchi further branch into bronchioles to finally lead the inhaled air into the alveoli ^[12].

Function of the Lobes of the Lungs

All the lung lobes have the same primary function – receiving oxygen-rich air as it travels down the airways and housing the oxygen-carbon dioxide exchange in the alveoli ^[13].

It is possible to remove one of the lobes surgically (lobectomy) in a life-threatening situation, like in a severe case of tuberculosis or lung cancer. This does affect the lung’s capacity, but in most cases, the person is still able to lead a normal lifestyle ^[14].