Spinal anaesthesia. Close-up of an anaesthesiologist placing an epidural needle into a patient's spine. The syringe (containing saline) is used to apply pressure as the needle is inserted. A drop in pressure tells the anaesthesiologist that the epidural space has been reached. An epidural anaesthetic is injected into the extradural space outside the dura mater (spinal cord membrane). It will cause a loss of sensation and loss of pain in the lower half of the body, allowing surgery to be performed. For footage of the actual catheter being inserted, see clip K003/3589.