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Brain Structure Spine

Epidural Space

spatium epidurale

The epidural space (extradural space) is the potential space between the dura mater of the spinal cord and the periosteum of the vertebral canal. It contains epidural fat, the epidural venous plexus (Batson plexus), spinal nerve root sleeves, and small arteries. The space is widest in the lumbar region (approximately 5-6 mm posterior midline) and narrows in the thoracic and cervical regions.

Anatomical Data

Structure & Connections

LocationVertebral canal, between the spinal dura and the bone and ligaments of the canal, from the foramen magnum to the sacral hiatus
Parts
  • Epidural fat
  • Internal vertebral venous plexus
  • Dural sleeves of the spinal nerve roots
  • Spinal branches of segmental arteries
  • Lymphatic vessels
Connections
  • Intervertebral foramina
  • Sacral hiatus (lower end)
  • Closed at the foramen magnum, where the dura fuses with bone
Blood SupplySpinal branches of the vertebral, intercostal, lumbar and lateral sacral arteries
Biomechanics

Function & Actions

Cushions the dural sac and lets it move with the spine. It is where epidural anaesthesia and steroid injections are placed. Inside the skull the dura is fixed to bone, so the epidural space there is only potential.

Clinical Relevance

Clinical Notes

The epidural space is the target for epidural anaesthesia and analgesia, used in obstetric pain management, thoracic and abdominal surgery, and post-operative pain control. The loss-of-resistance technique (to air or saline) identifies entry into the space as the needle passes through the ligamentum flavum. The epidural venous plexus is valveless and connects the pelvis to the intracranial venous sinuses (Batson pathway for metastatic spread). Epidural haematoma from anticoagulation or spinal cord injury compresses the cord and requires emergency decompression. Epidural abscess from haematogenous or contiguous spread causes progressive cord compression.

Pathology

Common Injuries & Conditions

Spontaneous Epidural Haematoma

Spontaneous epidural haematoma in anticoagulated patients or those with coagulopathy produces rapid posterior cord compression with acute onset of back pain followed by ascending weakness and sensory loss; emergency MRI confirms the haematoma and surgical decompression within 12 hours is the determinant of neurological recovery.

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