Preparation for spinal anaesthesia. An anaesthetist prepares a patient for spinal anaesthesia, by covering them with a plastic sheet exposing only the area of the spine where the injection will be administered. The spinal anaesthetic is injected into the subarachnoid space (the space between the inner-most and middle membranes of the three membranes that surround the spinal cord). Spinal anaesthesia is commonly used both alone and in combination with either sedation or general anaesthesia, for surgical procedures below the waist. See clip K004 6227