Sagittal section of lumbar area of spinal column showing pertinent anatomy. Needle inserted between vertebrae into cerebral spinal fluid (CSF).

Two cross-sections of spinal area showing congenital defect in which part of vertebral column is absent (top) and more extreme case where spinal cord protrudes beyond vertebral absence (bottom).

Posterolateral view of a section of the spinal column showing the vertebrae and their corresponding spinal nerves (spinal column not shown).

Sagittal section of lumbar area of spinal column showing pertinent anatomy. Needle inserted into epidural space between L3 and L4 vertebrae.

Sagittal section of lumbar area of spinal column showing pertinent anatomy. Needle is removed leaving catheter in place between L3 and L4 vertebrae.

Sagittal section of lumbar area of spinal column showing pertinent anatomy. Left: needle inserted into epidural space between L3 and L4 vertebrae. Right: Needle is removed leaving catheter in place.

Cross-section of the spinal column through a vertebra.