Spinal anaesthesia. Close-up of an anaesthesiologist threading a catheter (thin plastic tubing) into a needle that has been placed in the epidural space of a patient's spine. This is the extradural space outside the dura mater (spinal cord membrane). The catheter will be used to inject a local anaesthetic to numb the patient. The epidural anaesthetic 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 needle being inserted, see clip K003/3588.