A spinal anesthesia is a anesthesia of the lower body. It consists of injecting an anesthetic directly into the cerebrospinal fluid (CSF), the fluid that surrounds the spinal cord, at the level of the lower back between two lumbar vertebrae. It is a type of anesthesia widely used in surgery.

Spinal anesthesia is similar toepidural anesthesia, but the injection of the anesthetic does not take place in the same “compartment”.

Indeed, there are 3 membranes around the central nervous system (these are the meninges):

• la dura mater
• thearachnoid
• la pia mater

These delimit two spaces: epidural space and subarachnoid space (between the arachnoid and the pia mater, which contains the CSF),

Spinal anesthesia involves injecting the anesthetic into the subarachnoid space, while the anesthetic, during an epidural, does not cross the dura (protective membrane of the cerebrospinal fluid).