Costal Groove

sulcus costae

The costal groove is a groove on the inferior internal surface of each rib, running along most of the rib's posterior two-thirds from the rib angle to the costochondral junction. It houses the intercostal neurovascular bundle: the intercostal vein superiormost, the artery in the middle, and the nerve inferiormost (VAN from superior to inferior). The internal intercostal muscle forms the floor of the groove.

Region: Chest

Clinical Relevance

Clinical Notes

The costal groove dictates correct needle placement for intercostal nerve block: the needle is inserted just below the inferior rib margin at the posterior rib angle, where the groove is deepest and the neurovascular bundle most protected, advancing until the lower rib margin is contacted and then walking the needle just inferior. Anterior chest tube placement above the rib avoids the groove; however, the nerve may still be injured at the upper margin in some individuals where an accessory nerve runs superiorly. Thoracostomy tubes inserted too low risk the neurovascular bundle.

Pathology

Common Injuries & Conditions

Intercostal Neurovascular Bundle Injury in Chest Tube Placement

Chest tube or intercostal catheter placed at the lower rib margin or in the costal groove injures the intercostal vein, artery, and nerve, producing persistent haemothorax, intercostal neuropathic pain, and arterial haemorrhage; placement at the superior rib margin (avoiding the costal groove) prevents this complication.