The area below the right rib cage is medically known as the right upper quadrant (RUQ) of the abdomen. This region houses several major internal structures protected by the lower ribs. Understanding the anatomy of the RUQ is important because discomfort or pain here can signal an issue with one of these organs.
The Primary Organ: The Liver
The largest organ occupying the right upper quadrant is the liver. It rests immediately beneath the diaphragm, contoured to fit the muscle separating the chest from the abdomen. The liver is substantial, generally weighing between 3 and 3.3 pounds (1.4 to 1.5 kilograms) in an adult. This significant mass makes it the heaviest internal organ in the body. The liver is secured by various ligaments and is divided anatomically into a larger right lobe and a smaller left lobe.
Essential Roles of the Liver
The liver performs numerous functions essential for survival. One recognized function is detoxification, where it filters blood passing through it. The liver uses specialized enzyme systems to break down potentially harmful substances, such as metabolic waste, alcohol, and medications. It converts these into water-soluble compounds that can be safely excreted through urine or bile.
Metabolism is another primary role, involving the processing of fats, carbohydrates, and proteins absorbed from the digestive tract. For instance, the liver converts excess blood glucose into glycogen for storage, releasing it later to maintain stable blood sugar levels. It also synthesizes cholesterol and specific proteins required for fat transport and blood plasma production.
The liver also produces bile, a fluid essential for digestion. Bile contains bile salts that emulsify dietary fats, breaking large globules into smaller droplets to aid absorption in the small intestine. Approximately 800 to 1,000 milliliters of bile are produced daily, which also helps carry waste products like bilirubin out of the body.
Other Structures in the Right Upper Quadrant
Several other organs are located within or overlap the right upper quadrant. Tucked into a depression on the underside of the liver is the gallbladder, a small, pear-shaped reservoir. Its primary function is to store and concentrate the bile produced by the liver, releasing it into the small intestine when fatty food is consumed.
The upper pole of the right kidney is situated toward the posterior aspect of the RUQ, partially protected by the lower back ribs. Additionally, the hepatic flexure of the colon—the bend where the ascending colon meets the transverse colon—is located here. The head of the pancreas also extends into the RUQ, contributing digestive enzymes and hormones.
Common Causes of Discomfort in the Region
Pain or discomfort below the right rib cage often points to an issue with the liver or gallbladder. Gallstones, which are hardened deposits of digestive fluid, can block the bile ducts, leading to sudden, sharp pain known as biliary colic. Inflammation of the gallbladder, or cholecystitis, can result from a blockage and causes persistent pain, sometimes accompanied by fever.
Conditions affecting the liver, such as non-alcoholic fatty liver disease (NAFLD) or hepatitis, can also cause a dull, continuous ache. NAFLD involves the accumulation of excess fat in the liver cells, which can progress to inflammation and scarring. Pain can also originate from the right kidney, often associated with kidney stones or an infection like pyelonephritis.
Kidney stones cause severe pain that can radiate toward the back or groin, sometimes alongside painful or bloody urination. Any persistent, severe, or recurring pain in the right upper quadrant should prompt a consultation with a healthcare professional, as symptoms could be related to various underlying conditions requiring medical attention.