Neck flexion with spinal block. X-ray of a section through the cervical (neck) spine of a 58-year-old patient, showing reduced flexion after administration of a spinal block at the level of the C6-C7 vertebrae. A spinal block is the injection of a spinal anaesthetic into the subarachnoid space (the space between the inner-most and middle membranes of the three membranes that surround the spinal cord). It is used in addition to general anaesthesia when the surgery is being performed below the waste. The spinal anaesthetic will provide longer-lasting pain-relief after the surgery than just a general anaesthetic alone.