Lobes of Right Lung

1. Overview

The right lung is divided into three distinct lobes: the superior (upper) lobe, the middle lobe, and the inferior (lower) lobe. These lobes are separated by two prominent fissures—the horizontal fissure and the oblique fissure. Each lobe contains multiple bronchopulmonary segments and functions independently in respiration, making the right lung highly compartmentalized and functionally efficient. The additional lobe in the right lung, compared to the left, accommodates the asymmetrical position of the heart.

2. Location

The right lung is located within the right pleural cavity of the thorax and is:

• Larger and shorter than the left lung due to the presence of the liver below the right hemidiaphragm

• Situated lateral to the mediastinum and heart

• Superiorly bounded by the thoracic inlet, and inferiorly rests on the diaphragm

Each lobe is oriented as follows:

• Upper lobe: Anterior and superior region

• Middle lobe: Anterior and inferior to the upper lobe, anterior to the lower lobe

• Lower lobe: Posterior and inferior region of the lung

3. Structure

The right lung is anatomically subdivided by two fissures:

Horizontal Fissure

• Separates the upper lobe from the middle lobe

• Extends from the oblique fissure to the anterior chest wall at the level of the 4th rib

Oblique Fissure

• Separates the lower lobe from both the upper and middle lobes

• Runs from the T2 vertebral level posteriorly to the 6th rib anteriorly

Bronchopulmonary Segments

Each lobe contains specific segments supplied by individual segmental bronchi and arteries:

• Superior (Upper) Lobe: Apical, Posterior, Anterior

• Middle Lobe: Lateral, Medial

• Inferior (Lower) Lobe: Superior, Medial basal, Anterior basal, Lateral basal, Posterior basal

4. Function

Each lobe of the right lung serves critical roles in:

• Gas exchange: Housing alveoli for the diffusion of oxygen and carbon dioxide

• Ventilation: Air passage and distribution through its own bronchi and segments

• Mucociliary clearance: Filtering and expelling particles and microbes via ciliated epithelium

The division into three lobes allows the right lung to contribute efficiently to pulmonary function and adapt to partial loss of lobe function when necessary.

5. Physiological Role(s)

Physiologically, the lobes of the right lung contribute to:

• Independent ventilation-perfusion matching: Segmented nature allows each lobe to match blood flow with airflow effectively

• Mechanical efficiency: Division allows for more controlled lung expansion during inspiration

• Adaptability: If one lobe is compromised (e.g., collapsed or resected), others can compensate

6. Clinical Significance

Right Middle Lobe Syndrome

The right middle lobe, due to its small size and long narrow bronchus, is prone to collapse or chronic infection, especially in:

• Asthmatic patients

• Bronchiectasis

• Granulomatous diseases

Manifests as recurrent pneumonia or atelectasis seen on imaging.

Lobar Pneumonia

Each lobe can be independently affected by pneumonia. The right lower lobe is particularly vulnerable to aspiration pneumonia due to the more vertical orientation of the right main bronchus.

Pulmonary Embolism

Segmental emboli can occlude blood flow to specific lobes. A right lower lobe infarct is not uncommon and may present with pleuritic chest pain and hemoptysis.

Lung Cancer

Tumors can arise in any lobe; precise localization helps determine:

• Surgical approach (e.g., lobectomy vs. segmentectomy)

• Staging and lymphatic drainage patterns

The upper lobe is a common site for primary bronchogenic carcinoma.

Surgical Resection

Right lung lobectomy is more common due to the number of lobes. Knowing the lobe anatomy is essential for:

• Minimizing lung tissue loss

• Preserving postoperative pulmonary function

Radiological Interpretation

Accurate knowledge of right lung lobes and fissures aids in interpreting imaging findings on:

• Chest X-ray

• CT scan

• Bronchoscopy