Topics

Topic

design image
Left costophrenic angle

The left costophrenic angle is a sharp, acute recess formed at the junction of the left hemidiaphragm and the left lateral chest wall. It represents the most inferior lateral extent of the pleural cavity on the left side and is a key anatomic landmark in thoracic imaging.

This region is routinely evaluated on chest radiographs and cross-sectional imaging to assess pleural contour, lung expansion, and the interface between lung, pleura, and diaphragm.

Synonyms

  • Left costodiaphragmatic angle

  • Left pleurodiaphragmatic recess

Location

  • Situated at the inferolateral margin of the left hemithorax

  • Formed by the junction of the left hemidiaphragm and left chest wall

  • Lateral to the left cardiophrenic angle

  • Inferior to the left lower lobe of the lung

  • Corresponds roughly to the level of the 8th–10th ribs laterally (position varies with respiration)

Anatomical components

  • Left hemidiaphragm

  • Parietal pleura (costal and diaphragmatic pleura)

  • Visceral pleura of the left lung

  • Inferolateral margin of the left lower lobe

Relations

Superiorly:

  • Left lower lobe of the lung

Inferiorly:

  • Left hemidiaphragm

  • Upper abdominal structures (spleen, stomach fundus – indirectly)

Laterally:

  • Left lateral chest wall and ribs

Medially:

  • Left cardiophrenic region

X-ray appearance

Chest radiograph (PA view):

  • Left costophrenic angle: Sharp, acute V-shaped angle

  • Margins: Clearly defined interface between lung and diaphragm

  • Comparison: Typically slightly higher than the right due to cardiac position

Lateral chest radiograph:

  • Posterior costophrenic recess: Appears as a sharp posterior angle

  • Overlap: Visualized behind the cardiac silhouette

CT appearance

Lung window:

  • Left costophrenic angle: Clear triangular interface between aerated lung and diaphragm

  • Lung parenchyma: Normal aeration extending to the pleural margin

  • Pleural surface: Smooth contour along the diaphragm and chest wall

  • Recess visualization: Posterolateral extension of the pleural space well demonstrated

Mediastinal window:

  • Diaphragm: Well-defined muscular density

  • Pleura: Thin, normally imperceptible line

MRI appearance

T1-weighted images:

  • Lung: Low signal intensity due to air content

  • Diaphragm: Intermediate signal intensity muscle

  • Fat planes: High signal subdiaphragmatic and chest wall fat outlining the angle

T2-weighted images:

  • Lung: Very low signal

  • Diaphragm: Intermediate signal

  • Pleural interface: Thin low-signal line between lung and diaphragm

STIR:

  • Fat suppression: Suppresses chest wall and subdiaphragmatic fat

  • Diaphragm: Intermediate signal muscle clearly outlined

  • Costophrenic recess: Sharply delineated pleural boundary

CT image

Left costophrenic angle ct Anatomy, Location and Imaging Appearance

X-Ray image

Left costophrenic angle x ray Anatomy, Location and Imaging Appearance -img-00000-00000