Epidural administration (from Ancient Greek ἐπί, "on, upon" + dura mater) is a medical route of administration in which a drug or contrast agent is injected into the epidural space of the spinal cord. Techniques such as epidural analgesia and epidural anaesthesia employ this route of administration. The epidural route is frequently employed by certain physicians and nurse anaesthetists to administer diagnostic (e.g. radiocontrast agents) and therapeutic (e.g., glucocorticoids) chemical substances, as well as certain analgesic and local anaesthetic agents. Epidural techniques frequently involve injection of drugs through a catheter placed into the epidural space. The injection can result in a loss of sensation—including the sensation of pain—by blocking the transmission of signals through nerve fibers in or near the spinal cord.