Space
Horizontal fissure
Usual boundary between right superior and middle lobes
High-yield
This fissure is part of the standard right-lung pattern. Accessory fissures can occur elsewhere, so it is not an absolute rule that no left transverse fissure exists.
Overview
The horizontal fissure separates the superior and middle lobes on the right. It extends toward the anterior lung surface from the oblique fissure and may be incomplete or absent.
Reference facts
- Boundaries
- Facing visceral pleural surfaces of the right superior and middle lobes
- Contents
- A narrow pleural interval containing a lubricating fluid film
- Communications
- Continuous with the pleural space at the lung surface and meeting the oblique fissure laterally
Clinical correlation
Its position can shift with lobar volume change. Fluid trapped between the pleural surfaces may produce a mass-like radiographic opacity.
Frequently asked questions
What are the boundaries of the horizontal fissure?
The horizontal fissure is bounded by the facing visceral pleural surfaces of the right superior and middle lobes.
What does the horizontal fissure contain?
A narrow pleural interval containing a lubricating fluid film.
What does the horizontal fissure communicate with?
The horizontal fissure communicates with the continuous with the pleural space at the lung surface and meeting the oblique fissure laterally.