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Topographic Anatomy · Topographic Anatomy of the Chest

Topography of the Lungs

Pulmo

The lungs are paired respiratory organs located in the thoracic cavity and separated by the mediastinum. They exhibit pronounced anatomical asymmetry, a complex segmental structure, and a unique root topography, which is extremely important for surgical practice.

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Segments10 bronchopulmonary segments in each lung
Fissures on the rightOblique and horizontal fissures
Fissures on the leftOblique fissure only
LandmarkLower border descends during inspiration
4 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

General characteristics and surfaces

Each lung is a voluminous organ with three main surfaces:

  • Outer (costal) surface — lies against the inner surface of the ribs.
  • Lower (diaphragmatic) surface — rests on the diaphragm.
  • Inner (mediastinal) surface — faces the mediastinal organs.

A clear asymmetry of the lungs is observed. Due to the higher position of the right dome of the diaphragm and the displacement of the heart to the left, the right and left lungs differ in shape and size. Inferiorly, where the visceral pleura transitions into the parietal pleura, the pulmonary ligament (lig. pulmonale) is formed, which descends to the diaphragm, fixing the organ and dividing the pleural cavity.

Lobes, fissures, and borders

The left lung consists of two lobes (superior and inferior) separated by the oblique fissure (fissura obliqua). The right lung has three lobes: superior, middle, and inferior. In addition to the oblique fissure, there is a horizontal fissure (fissura horizontalis) separating the superior and middle lobes.

Lung borders have specific features:

  • Anterior border: Generally coincides with the border of the pleura. On the left, there is a deep cardiac notch (incisura cardiaca), due to which the cartilages of the 4th and 5th ribs are not covered by lung tissue.
  • Lower border: Located above the pleural border. At rest, on the right along the parasternal line, it passes at the level of the 6th rib, and along the scapular line — at the level of the 10th rib. During a deep breath, the lower border shifts significantly downward.
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Segmental structure

Each lung is divided into 10 bronchopulmonary segments. A segment is a pyramid-shaped portion of lung tissue with its apex directed toward the hilum of the lung. It is ventilated by a 3rd-order bronchus (segmental bronchus).

At the apex of the segment, its "stalk" is formed, including the segmental bronchus, artery, and central vein. It is important to note that the primary venous drainage occurs not through the central veins, but via intersegmental veins passing in the connective tissue septa between the segments.

Hilum and root of the lung

The hilum of the lungs (hilum pulmonis) is a depression on the medial surface of the organ through which the elements of the root pass. They project at the level of the 5th–8th thoracic vertebrae posteriorly.

The root of the lung (radix pulmonis) includes the main bronchi, pulmonary and bronchial vessels, lymph nodes, and nerves. The elements of the root are covered by the mediastinal pleura.

The syntopy of the root elements varies (from top to bottom):

  • Right: Main bronchus $\rightarrow$ Pulmonary artery $\rightarrow$ Superior pulmonary vein.
  • Left: Pulmonary artery $\rightarrow$ Main bronchus $\rightarrow$ Pulmonary veins.

In addition, the root of the right lung is arched by the azygos vein, and the root of the left lung by the aortic arch.

Briefly: answers to topical questions

What is the anteroposterior syntopy of the elements of the lung root?

The anteroposterior syntopy of the lung root elements differs on the right and left, with the veins typically occupying an anterior position.

  • Right lung — the pulmonary artery (a. pulmonalis) lies anterior to the main bronchus (bronchus principalis). The superior pulmonary vein is located anterior and inferior to the pulmonary artery.
  • Left lung — the main bronchus lies posterior to the pulmonary artery. The superior and inferior pulmonary veins (vv. pulmonales) are adjacent to the anterior and inferior surfaces of the bronchus and artery.

At what level does the lower border of the right lung pass along the midclavicular and midaxillary lines?

At rest, the lower border of the right lung passes along the midclavicular line at the level of the upper edge of the 7th rib, and along the midaxillary line at the level of the 8th rib.

Which specific bronchopulmonary segments form the superior lobe of the right lung?

The superior lobe of the right lung is formed by three specific pyramid-shaped bronchopulmonary segments.

  • Apical segment — segment I.
  • Posterior segment — segment II.
  • Anterior segment — segment III.

Each of these segments is ventilated by a corresponding segmental bronchus originating from the superior lobar bronchus before it enters the lung hilum.

Which groups of regional lymph nodes are located in the region of the hilum and root of the lung?

In the region of the hilum and root of the lung, bronchopulmonary nodes participate in lymph drainage, receiving the efferent lymphatic vessels from the lung, followed by tracheobronchial nodes (superior and inferior), and subsequently paratracheal and mediastinal nodes.

How to memorize

Root syntopy (top to bottom): Right — BAV (Bronchus, Artery, Vein). Left — ABV (Artery, Bronchus, Vein).

Class and exam questions

What is the anatomical difference between the main bronchi?

The right main bronchus is shorter, wider (about 2 cm in diameter), and runs more vertically, acting almost as a continuation of the trachea. The left main bronchus is longer, narrower (about 1.2 cm), and departs at a wider angle.

Where does the main venous drainage from the segment occur?

The main collector is the intersegmental veins, which are located in the connective tissue between the segments, collecting blood from adjacent areas.

What is the pulmonary ligament and what is its surgical significance?

This is a pleural fold descending from the lung hilum to the diaphragm. In surgery, this ligament must be transected during mobilization of the inferior lobe of the lung.

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What else to study on this topic

  • Projection of interlobar fissures onto the chest wall
  • Detailed nomenclature of all segments of the right and left lungs
  • Features of bronchial tree branching and the intermediate bronchus
  • Lymphatic system of the lungs and pathways of lymph drainage
  • Blood supply and innervation of the bronchial wall

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Other topics in the section "Topographic Anatomy of the Chest"

Topographic Anatomy of the ThoraxTopographic Anatomy of the Mammary GlandTopographic Anatomy of the DiaphragmMediastinumPericardiumTopographic Anatomy of the HeartThymusMajor Vessels of the Thoracic CavityAzygos and Hemiazygos VeinsTopographic Anatomy of the Trachea and BronchiTopographic Anatomy of the EsophagusThoracic DuctNerves of the Thoracic CavityTopography of the Pleural Cavity
The entire section "Topographic Anatomy of the Chest"

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