Rib Angle

angulus costae

The rib angle is the posterior curvature point of the rib where it bends abruptly forward to form the lateral chest wall, located approximately 5-6 cm lateral to the tubercle. The erector spinae muscles attach to the rib posterior to the angle. In thoracic deformity assessment, the rib angle prominence on one side in forward bending (the Adam forward bend test) reveals thoracic scoliosis with rotational deformity.

Anatomical Data

Structure & Landmarks

Articulations	No joint; surface landmark of rib shaft
Landmarks	5-6 cm lateral to rib tubercle Erector spinae attachment posterior to angle Intercostal neurovascular bundle runs in inferior groove from this point Adam forward bend test: rib hump at angle

Clinical Relevance

Clinical Notes

The rib angle is the entry point for erector spinae plane (ESP) block, an increasingly used regional anaesthesia technique that deposits local anaesthetic in the fascial plane between erector spinae and the transverse process, providing multilevel thoracic analgesia. Intercostal nerve blocks are placed at the rib angle where the nerve has cleared the costal groove of the rib above and the local anaesthetic spreads reliably. In scoliosis, the rib angle hump on the convex side reflects vertebral rotation.

Pathology

Common Injuries & Conditions

Rib Fracture at Rib Angle

The rib angle is a stress concentration point where both traumatic and fatigue fractures most commonly occur; a fracture at this level displaces the lateral rib anteriorly from the medial posterior segment, and multiple rib angle fractures (flail chest) require positive pressure ventilation support.

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