The area directly under the sternum, or breastbone, is known anatomically as the epigastric region. This central, upper abdominal space begins just beneath the xiphoid process, the small, pointed cartilage or bone at the very bottom of the sternum. This location is a junction where chest cavity structures meet the organs of the upper abdominal cavity. Discomfort felt here can originate from the digestive, muscular, and skeletal systems. Understanding the structures housed within this central zone is the first step toward determining the source of any sensation or pain.
The Primary Structures
The xiphoid process is the smallest and lowest segment of the sternum. This pointed structure is primarily cartilage in children but slowly ossifies into bone, often completing the process around age 40 or later. It provides an anchor point for several large muscles, most notably the diaphragm and the abdominal muscles.
The diaphragm is a dome-shaped sheet of muscle that sits directly beneath the ribcage, separating the thoracic and abdominal cavities. It attaches to the inner surface of the lower ribs and the xiphoid process, playing a mechanical role in respiration. The distal end of the esophagus, a muscular tube, passes through a small opening in the diaphragm called the esophageal hiatus. This tube connects the throat to the stomach, regulating the passage of swallowed food.
The stomach is the largest organ occupying the central upper abdomen, lying immediately below the diaphragm. It acts as a muscular reservoir for food, initiating digestion by mixing contents with strong acids and enzymes. Due to its central placement and function, the stomach is a frequent source of sensations felt in the epigastric region. The lower esophageal sphincter, a ring of muscle at the junction of the esophagus and stomach, controls the flow of contents between these two structures.
Neighboring Vital Organs
While the stomach occupies the center, several other major organs are tucked closely around it, influencing the epigastric region. The left lobe of the liver extends across the upper abdomen, often lying partially over the stomach and directly beneath the sternum. This lobe contributes to the central anatomy, though the liver’s bulk is predominantly located in the right upper quadrant.
The pancreas is positioned deeper within the abdominal cavity, situated horizontally behind the stomach. This gland secretes digestive enzymes into the small intestine and produces hormones like insulin. Because of its retroperitoneal location, pain originating from the pancreas can often be felt as a deep, radiating discomfort in the epigastric area.
The gallbladder stores and concentrates bile from the liver, situated slightly to the right of the midline. Although it is primarily associated with the right upper quadrant, pain from the gallbladder can sometimes be perceived in the central epigastrium due to shared nerve pathways.
Common Sources of Pain and Discomfort
A burning sensation in this area is frequently caused by Gastroesophageal Reflux Disease (GERD). GERD occurs when the lower esophageal sphincter weakens or relaxes, allowing acidic stomach contents to splash back into the esophagus. This acid irritates the sensitive lining, producing the sensation known as heartburn, often localized right behind the sternum. The resulting inflammation, or esophagitis, causes a sharp, burning discomfort that can mimic other conditions.
Peptic Ulcer Disease (PUD) involves open sores that form in the lining of the stomach (gastric ulcers) or the first part of the small intestine (duodenal ulcers). These ulcers develop when the protective mucosal barrier is damaged, allowing stomach acid and digestive juices to erode the tissue. The primary causes are infection with Helicobacter pylori bacterium or the prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs). Pain from a gastric ulcer typically occurs shortly after eating, while duodenal ulcer pain often presents a few hours later when the stomach is empty.
Musculoskeletal issues can also mimic organ pain, commonly involving the xiphoid process or the cartilage connecting the ribs to the sternum. Xiphoiditis is a localized inflammation of the xiphoid process that causes tenderness when pressure is applied to the bony tip. Costochondritis involves inflammation of the cartilage where the upper ribs attach to the breastbone. This inflammation results in sharp, localized chest wall pain that typically worsens with movement or deep breaths.