Anatomy of the epidural space

Despite the importance of anatomical knowledge in the safe and effective conduct of thoraco-lumbar epidural anaesthesia there are widespread misunderstandings about the detailed anatomy of this complex region. Current textbooks and teaching continue to propagate misleading information.Much of the difficulty in studying the lumbar epidural region is that the epidural space is a ‘potential’ space occupying only a small volume at rest but capable of expanding to accommodate large volumes of injected solution. This results in considerable distortion during some anatomical studies. However new imaging and dissection techniques have given us a much clearer insight into the anatomy and the relationships of the dura, epidural fat, blood vessels and spinal canal.This article seeks to provide an up-to-date account of current knowledge to give the reader a clearer idea of the true anatomy and how it might influence their epidural practice.