Abdominal discomfort can arise from a multitude of sources. One of these is the vagus nerve, the main neural pathway along which impulses travel to and from parts of your digestive system. Its role in controlling the rate at which your stomach releases acid and enzymes makes it a possible culprit for indigestion, albeit an uncommon one.
Indigestion -- that bloated, uncomfortable sensation you have when a meal doesn't seem to move properly through your gastrointestinal tract -- arises from a broad variety of causes. Overeating, eating too quickly, food poisoning and food sensitivities are just a few likely causes of occasional indigestion. Chronic indigestion may arise from an undiagnosed food intolerance, an esophageal or peptic ulcer, GERD -- gastroesophageal reflux disorder -- or one of a number of neurological or muscular conditions. The cause of chronic indigestion can be quite serious, so it's important to discuss the condition with your doctor.
Nerves transmit impulses that your brain deciphers as sensations. In the case of pinched nerves -- nerves that transmit impulses imperfectly or incompletely because of a constriction on the nerve bundle -- these sensations may create burning or painful sensations where there is no corresponding cause for the discomfort. True pinched nerves usually occur where nerve bundles traverse narrow passages such as the carpal tunnel of the wrist or the sciatic groove of the pelvis, but any neural restriction due to damage also may be termed a pinched nerve. Irritation or constriction in the splanchnic nerves that transmit stomach discomfort can feel like indigestion even when your digestive processes are working normally.
A special case of nerve impairment, gastroparesis refers to a slowing or cessation of food moving through the digestive system. Damage to the vagus nerve from surgery, injury or complications arising from diabetes can cause partial or total gastroparesis. Some medications also cause temporary gastroparesis. Drugs that affect smooth muscle tissue such as muscle relaxants or narcotics can cause gastroparesis-related indigestion. Your doctor can diagnose gastroparesis after ultrasound testing, examining your upper gastrointestinal tract with an endoscope or performing other necessary tests.
Referred pain occurs when your brain perceives pain from an injury or illness in a healthy part of the body that may be far removed from the site of the pain. One classic example of referred or heterotopic pain is the left arm pain that occurs during a heart attack. Gall bladder illness may make itself known as shoulder pain. A pinched nerve in your back might cause the abdominal discomfort you associate with indigestion.