lumbocostal triangle of diaphragm (vertebrocostal trigone or triangle, Bochdalek gap)

Introduction

A triangular area in the diaphragm between its lumbar & costal parts & superior to the lateral arcuate ligament that is devoid of muscle fibers.

• covered by pleura superiorly & peritoneum inferiorly
• a closure defect of the fetal pleuroperitoneal hiatus- if extensive, results in the most common site of diaphragmatic hernia of abdominal viscera

More general terms

• diaphragm muscle

Additional terms

• sternocostal triangle of diaphragm (sternocostal foramen)