Lung Fissures and Accessory Structures

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Questions and Answers

Which condition is most likely to cause hyperexpansion of the affected side in children?

Pleural effusion

Pulmonary mass

Foreign object aspiration (correct)

Acute respiratory distress syndrome

What type of atelectasis is commonly associated with mucus obstruction of small airways following surgery?

Adhesive atelectasis

Subsegmental atelectasis (correct)

Obstructive atelectasis

Cicatricial atelectasis

In which of the following scenarios is mucus plugging least likely to occur?

Right upper lobe

Lower lobes

Left upper lobe (correct)

Right middle lobe

Which characteristic sign is associated with lobar atelectasis?

Displacement of the fissures Signup and view all the answers

What is the primary cause of adhesive atelectasis seen in neonatal respiratory distress syndrome?

Surfactant deficiency Signup and view all the answers

What effect does oxygen inhalation have on the rate of obstructive atelectasis development?

Accelerates the development Signup and view all the answers

Which of the following conditions is characterized by volume loss due to architectural distortion caused by fibrosis?

Cicatricial atelectasis Signup and view all the answers

During an acute episode of lobar atelectasis, what is the most likely underlying cause?

Mucus plugging Signup and view all the answers

What anatomical structure does the minor fissure separate on the right side?

Right upper lobe and right middle lobe Signup and view all the answers

Which type of fissure is typically seen only on lateral radiographs?

Major (oblique) fissures Signup and view all the answers

In which percentage of patients is the inferior accessory fissure typically found?

12% Signup and view all the answers

What condition is characterized by the loss of lung volume due to decreased aeration?

Atelectasis Signup and view all the answers

Which statement about obstructive atelectasis is true?

It involves absorption of alveolar gas by the blood. Signup and view all the answers

What is the primary cause of atelectasis when it's induced by bronchial obstruction?

Mucus plugging Signup and view all the answers

Which structure is separated from the left upper lobe by the left minor fissure?

Superior lingula Signup and view all the answers

What is a direct sign of atelectasis indicative of lobar volume loss?

Lateral displacement of fissures Signup and view all the answers

Study Notes

Lung Fissures

Interlobar fissures separate lobes in the lungs.
Minor fissure separates the right upper lobe (RUL) from right middle lobe (RML) and is seen on frontal and lateral views as a horizontal line.
Major (oblique) fissures seen only on lateral radiographs as oblique lines; if fluid-filled, they appear on frontal views as concave curvilinear opacities in the lateral hemithorax.
Major fissure separates the RUL/RML in the right lung from the right lower lobe (RLL). -Separates the left upper lobe (LUL) from the left lower lobe (LLL) in the left lung.
Accessory fissures include:
- Azygos fissure (less than 1%): present with an azygos lobe
- Superior accessory fissure (approximately 5%): separates superior and basal segments of RLL.
- Inferior accessory fissure (approximately 12%, more common in right lung): divides medial basal segment from other basal segments.
- Left minor fissure (approximately 8%): separates lingula from LUL.

Atelectasis Overview

Atelectasis: loss of lung volume due to decreased aeration (collapse).
Causes: bronchial obstruction, mucus plugging, external compression (e.g., small lung volumes or pleural effusions).
Direct signs: from lobar volume loss (e.g., displacement of fissures).
Indirect signs: due to volume loss on adjacent structures (e.g., vascular crowding, elevation of diaphragm).
Air bronchograms: not seen in central bronchial obstruction atelectasis but can be seen in external compression atelectasis.

Mechanisms of Atelectasis

Obstructive atelectasis: alveolar gas absorbed by blood, not replaced by inspired air due to bronchial obstruction.
Can cause lobar atelectasis (complete lobe collapse).
More rapid with supplemental oxygen (oxygen absorption faster than nitrogen).
In children, airway obstruction often due to aspirated foreign objects, causing hyperexpansion of affected side.
Subsegmental atelectasis: common after surgery or illness, due to mucus obstruction of small airways.
Relaxation (passive) atelectasis: lung relaxation adjacent to intrathoracic lesions (e.g., pleural effusion, pneumothorax, pulmonary mass).
Adhesive atelectasis: due to surfactant deficiency, common in neonatal respiratory distress syndrome and ARDS.
Cicatricial atelectasis: volume loss from architectural distortion by fibrosis.

Lobar Atelectasis

Usually caused by central bronchial obstruction (obstructive atelectasis), possibly due to mucus plugging or tumor.
Acute lobar atelectasis: likely due to mucus plugging (more common in lower lobes, less common in LUL).
Outpatient lobar atelectasis: must rule out obstructing central tumor.
Characteristic appearances depending on affected lobe:
- Displacement of fissures
- Plate-like/triangular opacity from collapsed lung.
- Vascular crowding
- Diaphragm elevation
- Rib crowding on affected side
- Mediastinal shift to affected side
- Overinflation of adjacent/contralateral lobes
- Hilar displacement

Patterns of Lobar Atelectasis

Illustrations show collapse direction of each lobe (RUL, LUL, RML, RLL, LLL) for frontal and lateral views.

Left Upper Lobe Atelectasis

Left upper lobe collapse & luftsichel sign: frontal radiograph shows veil-like opacity.

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Description

Explore the various lung fissures, including minor and major fissures that separate different lobes of the lungs. This quiz also covers accessory fissures and their anatomical significance in both the right and left lungs. Test your knowledge on these important aspects of pulmonary anatomy.