Intrathecal injection pertains to injection of substances through the thecal membrane and into the subarachnoid space surrounding the spinal cord. Epidurals such as the analgesics used to control pain during childbirth and chemotherapeutic agents are administered in this manner.
Anterior view of the spinal cord
Lateral view of the spinal cord
Chabner, Davi-Ellen. 2007. The Language of Medicine. 8th ed. Saunders Elsevier, Missouri