This study evaluates whether combining two distinct pain-relief techniques-a peripheral nerve block called the Erector Spinae Plane Block (ESPB) and a low-dose spinal medication injection called Intrathecal Morphine (ITM)-provides better postoperative pain management for adult patients undergoing major midline abdominal surgery (laparotomy) compared to using either technique alone. The main goal is to see if this combination improves pain control and reduces the total amount of opioids required by patients within the first 48 hours after surgery.