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Topic

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Middle lobe of right lung

The middle lobe of the right lung is one of the three lobes of the right lung, positioned anteroinferiorly between the upper and lower lobes. It is relatively small and wedge-shaped and is uniquely bordered by both the horizontal and oblique fissures. Its anatomical position makes it particularly important in chest imaging interpretation.

The right middle lobe is a key region assessed on chest radiographs and cross-sectional imaging for normal lobar anatomy, fissural orientation, and segmental relationships.

Synonyms

  • Right middle lobe

  • Middle lobe of right lung

Location

  • Located in the right hemithorax

  • Positioned anteromedially within the right lung

  • Inferior to the right upper lobe

  • Anterior to the right lower lobe

  • Between the horizontal fissure superiorly and the oblique fissure inferiorly

  • Adjacent to the right cardiac border medially

Anatomical components

  • Two bronchopulmonary segments:

    • Medial segment (S5)

    • Lateral segment (S4)

  • Segmental bronchi:

    • Medial segmental bronchus

    • Lateral segmental bronchus

  • Segmental pulmonary arteries and veins following bronchial anatomy

Relations

Superiorly:

  • Horizontal fissure

  • Right upper lobe

Inferiorly:

  • Oblique fissure

  • Right lower lobe

Medially:

  • Right atrium

  • Right heart border

  • Mediastinum

Laterally:

  • Costal pleura

  • Chest wall

Anteriorly:

  • Anterior chest wall

Posteriorly:

  • Oblique fissure

  • Lower lobe structures

X-ray appearance

Chest radiograph (PA view):

  • Normally not seen as a separate lobe

  • Forms part of the right cardiac silhouette

  • Right heart border remains sharp when middle lobe is aerated

Lateral view:

  • Occupies the anteroinferior portion of the lung

  • Located between the horizontal and oblique fissures

  • Wedge-shaped opacity region corresponding to middle lobe location

CT appearance

Lung window:

  • Well-aerated lung parenchyma with uniform low attenuation

  • Clearly defined horizontal and oblique fissures bounding the lobe

  • Medial and lateral segments identifiable by bronchovascular anatomy

  • Middle lobe bronchus arising from the bronchus intermedius

  • Sharp interface with adjacent upper and lower lobes

MRI appearance

T1-weighted images:

  • Aerated lung: Low signal intensity

  • Bronchovascular structures: Intermediate signal

  • Middle lobe boundaries: Appreciated by fissural planes

T2-weighted images:

  • Lung parenchyma: Low signal due to air content

  • Vessels: Higher signal relative to lung

  • Fissures: Thin linear low-signal interfaces

STIR:

  • Lung parenchyma: Suppressed low signal

  • Bronchovascular structures: Relatively higher signal

CT image

Middle lobe of right lung of right lung CT anatomy image -img-00000-00000

X-Ray image

Middle lobe of right lung X RAY anatomy image -img-00000-00000

CT image

Middle lobe of right lung CT Anatomy, Location and Imaging Appearance CT anatomy image -img-00000-00000