Lobes of the Lungs

The lungs are one of the most important organs present in the body. These are the organs of the respiratory system that are responsible for helping us breathe and thus, actually form the main part of the respiratory system. The nose leads into the trachea, which then splits into two bronchi, which in turn branch into various bronchioles. These bronchioles then lead into small alveoli, which is where the exchange of air takes place. The lungs are basically made up of parenchymatous tissue that is present in this form on the right and left, which thus, constitutes the right and the left lungs. Each lung has a specific number of lung lobes.

Right Lung
The right lung has three lung lobes. These are the superior, middle and inferior lobes. These are separated from each other by the interlobular fissures. One of these fissures, the oblique fissure, separates the inferior lobe of the lung from the middle and superior lobes. This fissure corresponds closely with the fissure in the left lung. However, its direction is more vertical and it cuts the lower border around 7.5 cm behind its anterior extremity. The other fissure, which is the horizontal fissure, separates the superior from the middle lobe. This fissure begins in the previous fissure near the posterior border of the lung and running horizontally forward, cuts the anterior border on a level with the sternal end of the fourth costal cartilage. On the mediastinal surface of the lung, it may be traced backwards to the hilum.

The middle lobe is the smallest of all the lung lobes of the right lung. It is wedge-shaped and includes the lower part of the anterior border and the anterior part of the base of the lung. The right upper lobe is one of the largest lobes of the lungs and is located on the anterior surface of the chest, taking up most of the space here. One the other hand, the inferior right lobe is primarily located towards the posterior surface of the chest and very little is projected onto the anterior chest. The right lung is shorter than the left lung by about five centimeters. This is due to the diaphragm rising higher on the right side so as to accommodate the liver. However, the right lung is broader due to the inclination of the heart on the left side. Due to this reason, the total capacity, volume and weight of the right lung is more than that of the left lung.

Left Lung
The left lung is divided into two lobes, an upper and a lower lobe. This upper and lower lobe is divided by a fissure known as oblique fissure. This fissure extends from the costal to the mediastinal surface of the lung, both above and below the hilum. This fissure begins on the mediastinal surface of the lung at the upper and posterior part of the hilum and then runs backwards and upwards to the posterior border which it crosses at a point about six centimeters below the apex of the left lung.

The superior lobe, which is the smaller of the two lobes of the lungs, lies above and in front of this fissure and includes the apex, the anterior border and a part of the costal surface and the greater part of the mediastinal surface of the lung. The inferior lobe is larger of the two lung lobes and is situated below and behind the fissure and comprises almost the entire base, a large portion of the costal surface and a greater part of the posterior border. The lobe that is missing or is not present in the left lung when compared to the right lung is the middle lobe. Instead there is a small projection of the upper lobe of the left lung which is known as lingula. The reason why there is no middle lobe, which makes the left lung smaller than the right, is to make room for the human heart.

All the lung lobes have the same function of aiding in respiration and exchange of gases. Thus, all are susceptible to suffering from lung diseases due to smoking or other internal and external factors.