• Epidural space
• Dural sac ends at S2 and continues as the filum terminale
• Dural sac contains anterior and posterior spinal nerve roots
• Borders
• Superior
• Fusion of spinal and periosteal layers of dura at foramen magnum
• Inferior
• Sacrococcygeal membrane
• Anterior
• Posterior longitudinal ligament, vertebral bodies and discs
• Lateral
• Pedicles and intervertebral foraminae
• Locating the space
• Interlaminar
• Transforaminal
• Transsacral
• Direct vision with spinal endoscope
• Paravertebral
• Lymphatics
• Present mostly around nerve roots
• Nerve supply
• Posterior dura is sparsely supplied. Direct branches of sympathetic chain & sinu-vertebral nerves from the rami communicantes
• Blood supply
• Arterial
• Anterior and posterior arterial (and venous) arcade forms from spinal arteries entering through the intervertebral foraminae.
• Atery of Ademkevicz
• Venous
• Valveless venous plexus of Batson drains into thoracic and lumbar intervertebral foraminae into ascending lumbar and thoracic (hemiazygous and azygous veins). Higher venous channels can drain into cerebral plexuses