Prof. Ashok Sundararaman, MS, FRCS, FICS,* Most diseases of the abdominal viscera are associated with pain sometime during their course. A brief review of abdominal embryology and pain physiology will assist the clinician in evaluating the patient with acute or chronic abdominal pain. The gastrointestinal tract comprises of Foregut, Midgut, Hindgut. Each segment has its own blood supply and innervation. Foregut: Oropharynx to duodenum up to the level of insertion of common bileduct including liver, biliary tree, pancreas and spleen. Midgut: Distal duodenum, jejunum, ileum, appendix, ascending colon, proximal 2/3rd of transverse colon. Hindgut: Remainder of colon and rectum up to dentate line. Peritoneum : Is a continuous visceral and parietal layer. Both are derived from mesoderm but develop separately. Nerve supply is different. Visceral layer : Autonomic nerve (sympathetic & parasympathetic). Parietal layer: Somatic innervation (spinal nerves). Pathways of pain for the visceral and parietal layer are different and the quality is different as well. Visceral pain: Dull, crampy and aching. Parietal pain: Sharp, secure and persistent. Pain map of the abdomen. Ant & Lat abdominal walls T7-T11. Posterior abdominal walls L2-L5. Pattern Recognition in abdominal pain. Referred pain: Right shoulder diaphragm, gall bladder, liver capsule, pneumoperitoneum. Left shoulder diaphragm, spleen, tail of pancreas, stomach, splenic flexure, pneumoperitoneum. Right scapula gall bladder, biliary tree. Left scapula spleen, tail of pancreas. Groin/genital kidney, ureter, aorta and iliac. Back _ midline pancreas, duodenum, aorta. Acute abdominal pain: Pain present for less than eight hours. Careful and thorough history important. Early diagnosis is the key to management.