Lung Lobes: Definition, Anatomy, Functions, Picture | The Respiratory System
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Published on November 13th 2017 by under

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].

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