Costophrenic Ligament

ligamentum costophrenicum

The costophrenic ligament refers to the fibrous attachment of the peripheral diaphragm to the costal margin, creating the costophrenic recess of the pleural cavity. The sharpness of the costophrenic angle on chest radiograph indicates pleural space integrity — blunting requires at least 200-300 ml of pleural fluid to develop.

Region: Chest

Anatomical Data

Origin, Insertion & Supply

Origin	Lower ribs (costal margin)
Insertion	Peripheral diaphragm

Biomechanics

Function & Actions

Actions	Anchors the peripheral diaphragm to the costal margin; defines the costophrenic sulcus visible on chest radiograph

Clinical Relevance

Clinical Notes

Costophrenic angle blunting on chest radiograph is the first radiographic sign of pleural effusion, requiring at least 200-300 ml of fluid to produce. Obliteration of the costophrenic angle on PA chest X-ray versus lateral views helps quantify effusion volume. The pleural recess at the costophrenic sulcus is the dependent position where effusions pool.

Pathology

Common Injuries & Conditions

Pleural Effusion

Fluid accumulation in the costophrenic recess blunting the costophrenic angle on chest radiograph from cardiac, hepatic, malignant, or infectious causes.