The human right lung is divided into three lobes (as opposed to two lobes on the left), superior, middle, and inferior, by two interlobular fissures:

Fissures

• One of these, the oblique fissure
  Oblique fissure
  In the lung, the oblique fissure separates the inferior lobe of either lung from the remainder of the lung. The oblique fissure extends from the spinous process of T2...
  
  , separates the inferior from the middle and superior lobes, and corresponds closely with the fissure in the left lung
  Left lung
  The human left lung is divided into two lobes, an upper and a lower, by the oblique fissure, which extends from the costal to the mediastinal surface of the lung both above and below the hilum....
  
  . Its direction is, however, more vertical, and it cuts the lower border about 7.5 cm. behind its anterior extremity.

• The other fissure, the horizontal fissure
  Horizontal fissure of right lung
  The horizontal fissure of right lung is a fissure separating the superior lobe from the middle lobe.The left lung has no middle lobe, so there is no horizontal fissure on that lung....
  
  , separates the superior from the middle lobe. It 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 it may be traced backward to the hilum
  Hilum of lung
  Above and behind the cardiac impression is a triangular depression named the hilum, where the structures which form the root of the lung enter and leave the viscus. These include the pulmonary artery, superiormost on the left lung, the superior and inferior pulmonary veins, lymphatic vessels and...
  
  .

Lobes

The middle lobe, the smallest lobe of the right lung, is wedge-shaped, and includes the lower part of the anterior border and the anterior part of the base of the lung. (There is no middle lobe on the left lung

Left lung

The human left lung is divided into two lobes, an upper and a lower, by the oblique fissure, which extends from the costal to the mediastinal surface of the lung both above and below the hilum....

, though there is a lingula

Lingula of left lung

The human left lung, unlike the right, contains no middle lobe. However, the term lingula is used to denote a projection of the upper lobe of the left lung that serves as the homologue. Some sources define the lingula as a distinct lobe...

.)

The superior and inferior lobes are similar to their counterparts on the left lung

Left lung

The human left lung is divided into two lobes, an upper and a lower, by the oblique fissure, which extends from the costal to the mediastinal surface of the lung both above and below the hilum....

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Difference in size

The right lung, although shorter by 5 cm. than the left, in consequence of the diaphragm

Thoracic diaphragm

In the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration...

 rising higher on the right side to accommodate the liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, is broader, owing to the inclination of the heart to the left side. Consequently, the volume, the total capacity and the weight of the right lung is higher than that of the left.

Impressions

On the mediastinal surface, immediately above the hilum, is an arched furrow which accommodates the azygos vein

Azygos vein

The azygos vein is a vein running up the right side of the thoracic vertebral column. It can also provide an alternate path for blood to the right atrium by allowing the blood to flow between the venae cavae when one vena cava is blocked.-Structure:...

; while running upward, and then arching lateralward some little distance below the apex, is a wide groove for the superior vena cava

Superior vena cava

The superior vena cava is truly superior, a large diameter, yet short, vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium...

 and right innominate vein; behind this, and nearer the apex, is a furrow for the innominate artery.

Behind the hilum and the attachment of the pulmonary ligament

Pulmonary ligament

The root of the lung is covered in front, above, and behind by pleura; at its inferior border, the investing layers come into contact. Here they form a sort of mesenteric fold, the pulmonary ligament, which extends between the inferior part of the mediastinal surface of the lung and the pericardium...

 is a vertical groove for the esophagus

Esophagus

The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...

; this groove becomes less distinct below, owing to the inclination of the lower part of the esophagus to the left of the middle line.

In front and to the right of the lower part of the esophageal groove is a deep concavity for the extrapericardiac portion of the thoracic part of the inferior vena cava

Inferior vena cava

The inferior vena cava , also known as the posterior vena cava, is the large vein that carries de-oxygenated blood from the lower half of the body into the right atrium of the heart....

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External links

• Lung Lobes - "Mediastinal surface of the right lung."
• Diagram and quiz at cancer.gov
• Cross section at univie.ac.at