Spinal anesthesia, also known as subarachnoid block or spinal block, is a medical procedure that involves injecting an anesthetic solution into the cerebrospinal fluid surrounding the spinal cord. This type of anesthesia is commonly used for surgery on the lower half of the body, such as the legs, hips, pelvic region, and lower abdomen. Synonyms for spinal anesthesia include neuraxial anesthesia, intrathecal anesthesia, and subdural block. Neuraxial anesthesia refers to an anesthetic technique that acts on the nerves that transmit sensory information to the brain and includes both spinal and epidural anesthesia. Intrathecal anesthesia involves injecting the anesthetic solution directly into the subarachnoid space, while subdural block targets the fluid-filled sac surrounding the spinal cord.