The area beneath the right rib cage is anatomically known as the right upper quadrant (RUQ). This region contains several organs essential for digestion and metabolism. When people feel discomfort here, they are often feeling a sensation near the body’s largest solid organ, the liver. The liver occupies the majority of the space directly beneath the diaphragm on the right side.
The Liver: The Largest Occupant
The liver is a reddish-brown, wedge-shaped organ that typically weighs about three pounds in an adult. It is situated primarily in the right upper quadrant, with its lower edge tucked beneath the rib cage. The hepatocytes, or liver cells, perform over 500 different functions, regulating nearly all chemical levels in the blood. A primary role is detoxification, converting toxic substances, like ammonia from protein metabolism, into the less harmful urea, which is then excreted by the kidneys.
The liver synthesizes many proteins, including albumin, which regulates fluid balance, and various clotting factors necessary for blood coagulation. It is also a central hub for nutrient management, storing excess glucose as glycogen and releasing it back into the bloodstream to maintain stable blood sugar levels. The liver produces approximately 800 to 1,000 milliliters of bile each day, a greenish-yellow fluid crucial for fat digestion and waste removal.
The Gallbladder and Biliary System
Tucked into a shallow depression on the underside of the liver is the gallbladder, a small, pear-shaped, hollow organ. Its main purpose is to store and concentrate the bile fluid created by the liver. The gallbladder typically holds about 30 to 60 milliliters of bile, making it significantly more potent for fat emulsification.
The biliary system is a network of ducts connecting the liver, the gallbladder, and the small intestine. Bile flows from the liver through the hepatic ducts into the cystic duct, leading to the gallbladder for storage. When fatty food enters the small intestine, the gallbladder contracts to release the concentrated bile through the common bile duct into the duodenum. Issues affecting the gallbladder’s function, such as blockages, frequently cause sudden, intense pain in the RUQ.
Important Neighboring Structures
While the liver and gallbladder are the most prominent organs in the right upper quadrant, several other structures are situated nearby, and problems with them can mimic pain in the area. The diaphragm, the large dome-shaped muscle responsible for breathing, forms the roof of the RUQ, separating the abdomen from the chest cavity. Issues involving the diaphragm or the lower right lung can sometimes cause pain that feels like it originates under the ribs.
The Right Kidney
The right kidney sits lower and farther back in the abdominal cavity, partially protected by the lower ribs. A kidney infection or a stone high in the urinary tract can cause referred pain to the front of the abdomen.
The Hepatic Flexure
The hepatic flexure is the bend in the large intestine where the ascending colon meets the transverse colon, located directly beneath the liver. Trapped gas or inflammation in this section of the colon can also contribute to localized discomfort.
Common Sources of Pain in This Region
Pain originating in the right upper quadrant most often relates to the gallbladder or the liver. Inflammation of the gallbladder, known as cholecystitis, is a common source of acute pain, frequently occurring when gallstones block the cystic duct. These hardened deposits of cholesterol or bile salts cause sharp, cramping pain, particularly following a meal high in fat. Conditions affecting the liver, such as hepatitis, can also result in localized tenderness, stemming from viral infections, excessive alcohol consumption, or certain medications. Less common sources of pain include musculoskeletal issues, such as costochondritis, or a simple rib injury.