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.

The spinal cord within the bony vertebral canal. Emergence of spinal nerves at various levels.

Cross-section of thorax at L3-L4 disc showing relevant lumbar anatomy; two spinal needles illustrate the medial and lateral approaches into the subarachnoid space where the cerebrospinal fluid is located.

Transverse sections of the cervical (top), thoracic (2nd), lumbar (3rd), and sacral (4th) portions of the spinal cord. (DF, dorsal funiculus; LF, lateral funiculus; VF, ventral funiculus).

Lumbar vertebra & spinal canal, cross section