The anatomy of the epidural space

Abstract 

The epidural space is important to the anaesthetist as the site for epidural block. It surrounds the spinal part of the dura and extends from the foramen magnum of the skull to the sacral hiatus. It contains the vertebral plexus of veins, small arteries, lymphatics and the epidural fat. This fat is loose and allows injected fluid to diffuse through it. The space projects through each intervertebral canal to lie behind the parietal pleura, whose negative pressure is transmitted to it. Anteriorly, the space lies against the posterior aspects of the vertebral bodies covered by the posterior longitudinal ligament. Also connecting the vertebral bodies are the anterior vertebral longitudinal ligament and the intervertebral discs, made up of the annulus fibrosus and the central nucleus pulposus. Posteriorly, the spines are connected by the weak interspinous and powerful supraspinous ligament (the ligamentum nuchae in the cervical region), while the elastic ligamentum flavum attaches adjacent laminae.

Keywords: anterior longitudinal ligaments, epidural space, interspinous ligaments, intervertebral disc, posterior ligaments, supraspinous ligaments, vertebral venous plexus