Which Organs Are Under the Right Breast?

Several organs sit directly beneath the right breast, spanning two major body compartments. Above the diaphragm, the right lung and its surrounding membrane fill most of the space behind the chest wall. Below the diaphragm, the liver dominates the right upper abdomen, with the gallbladder tucked against its underside and the right kidney sitting further back. Because these structures are layered at different depths and overlap one another, pain or discomfort “under the right breast” can originate from surprisingly different sources.

The Chest Wall Itself

Before reaching any organ, you pass through layers of tissue that make up the chest wall. The breast rests on top of the pectoralis major muscle, separated from the ribs by a layer of connective tissue called the pectoralis fascia. Beneath that lie the ribs, intercostal muscles running between them, and the thin pleural membrane that lines the inner surface of the rib cage. Each of these layers can be a source of discomfort on its own. Strained intercostal muscles, bruised ribs, or inflammation of the cartilage connecting a rib to the breastbone (costochondritis) can all produce sharp, localized pain that feels as though it is coming from inside the chest when it is really coming from the wall.

Running along the inner surface of the chest wall, just beside the breastbone, are the internal thoracic arteries and veins. These vessels send perforating branches outward through the upper intercostal spaces, supplying blood to the breast tissue and the skin over the sternum. An anatomical study found that large perforating branches emerged from the first and second intercostal spaces in roughly nine out of ten people, with the frequency dropping in the lower spaces.¹ This vascular architecture matters in breast surgery and reconstruction, but for everyday purposes it just means the chest wall beneath your breast is richly supplied with blood and therefore sensitive to inflammation or injury.

The Right Lung and Pleura

The right lung is the largest organ behind the right breast. It has three lobes (compared to two on the left side, where the heart takes up space), and the lower lobe extends surprisingly far down, reaching almost to the bottom of the rib cage when you take a deep breath. The lung itself has no pain nerves, but the pleura, the double-layered membrane surrounding it, is highly sensitive. When the pleural lining becomes inflamed (pleurisy) or when air or fluid collects in the pleural space, you can feel a stabbing pain in the chest wall that worsens with breathing. Because the lower right lung sits directly behind the right breast, this kind of pain often localizes there.

Conditions like pneumonia, a pulmonary embolism (a blood clot that travels to the lung), or a collapsed section of lung can all produce pain in this region. The pain tends to be sharp and linked to your breathing cycle, which usually helps distinguish it from pain arising in the abdomen below.

The Diaphragm

Separating the chest from the abdomen is the diaphragm, a dome-shaped sheet of muscle that flattens each time you inhale. On the right side, the diaphragm sits higher than on the left because the liver pushes it upward from below. This means the right dome of the diaphragm lies directly beneath the lower ribs, roughly at the level where the breast ends. Irritation of the diaphragm, whether from an abscess just below it, inflammation of the liver surface, or even trapped gas pressing upward from the abdomen, can cause pain that you feel under the right breast or at the tip of the right shoulder. That shoulder referral happens because the phrenic nerve, which controls the diaphragm, shares spinal cord roots with nerves that supply the shoulder skin.

The Liver

The liver is the single largest solid organ in the abdomen and the one most closely associated with the space under the right breast. It fills most of the right upper quadrant, wedge-shaped and tucked snugly beneath the diaphragm. Its upper edge reaches as high as the fifth rib in many people, which puts a substantial portion of the liver directly behind and below the right breast. The liver extends across the midline to the left as well, but its bulk is overwhelmingly on the right.

Because the liver is so large and sits so high, numerous conditions affecting it can produce discomfort under the right breast. Hepatitis (inflammation of the liver from infection, alcohol, or other causes), liver cysts, fatty liver disease, and liver tumors can all cause a dull ache or feeling of fullness in the right upper abdomen that radiates upward. The liver’s capsule, a thin layer of connective tissue surrounding it, is loaded with nerve endings, so anything that stretches or inflames that capsule, whether rapid swelling from heart failure or an abscess forming within the liver, tends to hurt.

The Gallbladder

Nestled against the undersurface of the liver, roughly at the point where the right rib cage meets the midline, the gallbladder is a small, pear-shaped sac that stores bile. It sits close enough to the surface that a doctor can sometimes detect tenderness there just by pressing under the right rib margin while you breathe in. Gallstones are one of the most common causes of sharp right upper quadrant pain, and because the gallbladder sits so high, the pain frequently radiates into the area under and around the right breast. Gallbladder attacks often involve intense, crampy pain after eating fatty food, sometimes accompanied by nausea. An ultrasound of the right upper quadrant is the standard first step when this kind of pain arises, and it can reveal conditions involving the liver, gallbladder, kidney, adrenal gland, and even parts of the gastrointestinal tract.²

The Right Kidney and Adrenal Gland

The right kidney sits behind the other abdominal organs, pressed against the muscles of the back wall, at roughly the level of the lowest two ribs. It is slightly lower than the left kidney because the liver pushes it down. Sitting on top of the kidney like a cap is the right adrenal gland, a small, triangular endocrine gland that produces hormones including cortisol and adrenaline. Both structures are far enough toward the back that pain originating from them tends to be felt in the flank or back, but kidney infections, large kidney stones, or adrenal tumors can sometimes cause pain that wraps around toward the front, reaching the area under the right breast.

The kidney’s position relative to the ribs changes with your posture. Research using imaging in both lying-down and seated positions found that the right kidney’s rib coverage changed significantly between the two postures, meaning the lower ribs shielded more or less of the kidney depending on whether a person was sitting up or lying flat.³ This matters for understanding why kidney pain can feel slightly different depending on your position, and it also matters clinically when imaging these organs or assessing vulnerability to blunt trauma.

Parts of the Digestive Tract

Several segments of the gastrointestinal tract pass through the right upper quadrant, putting them in the neighborhood of the right breast. The duodenum, the first stretch of the small intestine just past the stomach, curves in a C-shape around the head of the pancreas, and the upper portion of that C sits high in the right abdomen. The hepatic flexure of the colon, the sharp bend where the ascending colon turns to become the transverse colon, sits just below and slightly in front of the liver. A case report of right upper quadrant pain traced the cause to an inflammatory condition at this exact spot, with imaging showing an inflamed mass wedged between the hepatic flexure and the lower edge of the liver.⁴

Even the stomach, which is predominantly a left-sided organ, has its outlet (the pylorus) pointing toward the right, connecting to the duodenum in the upper right quadrant. So while stomach pain is classically felt in the upper center or left side of the abdomen, conditions affecting the pylorus or duodenum can produce discomfort that is felt further to the right than most people expect.

Why Pain Under the Right Breast Can Fool You

One of the trickier aspects of this region is referred pain, where a problem in one organ produces a sensation you feel somewhere else. The nervous system is partly to blame. Internal organs do not have the same precise nerve mapping that your skin does, so pain signals from the gut, liver, or diaphragm get routed through spinal cord segments that also serve the chest wall and skin. Your brain interprets the signal as coming from the surface, even though the source is deep inside.

A striking example involves the duodenum. A case study described a patient with a duodenal ulcer whose primary complaint was persistent pain in the right side of the chest, specifically along the mid-chest wall. Nociceptive signals from the duodenum travel to the spinal cord through nerve roots spanning from roughly the mid-back down, which means duodenal pain can genuinely radiate into the chest wall rather than just the belly.⁵ The pain was not recognized as a gut problem for some time because it did not match the textbook expectation of abdominal pain from an ulcer. This kind of mismatch between where something hurts and where the problem actually is explains why doctors sometimes cast a wide diagnostic net for right-sided chest pain, checking organs in both the chest and the abdomen.

Gallbladder pain can similarly radiate to the right shoulder blade or right mid-back, and liver surface irritation can send pain up toward the right shoulder via the phrenic nerve. The lesson for someone experiencing persistent or severe pain under the right breast is that the cause may not be in the most obvious spot. A pulled muscle in the chest wall, a lung problem, a liver or gallbladder condition, a kidney stone, or even an ulcer in the duodenum could all be responsible.

How Body Size, Posture, and Pregnancy Shift Things Around

The organs under your right breast are not bolted in place. Body size, posture, and life circumstances all move them. Taller people tend to have longer torsos, which means the liver sits slightly lower relative to the ribs compared to shorter individuals. In people with a larger body habitus, the abdominal organs can be pushed upward against the diaphragm by visceral fat, making the liver feel even more prominent beneath the right rib cage.

Posture makes a measurable difference. Moving from lying flat to sitting up shifts the kidneys, spleen, and liver downward relative to the ribs. The same imaging study that found changes in rib coverage for the right kidney also documented shifts in organ location and shape between postures.³ This is why a physical exam sometimes involves different positions: what a doctor can feel under your ribs changes depending on whether you are standing, sitting, or lying down.

Pregnancy is the most dramatic example. As the uterus expands, it pushes abdominal organs upward and to the sides. The liver and gallbladder get displaced superiorly and laterally, and the intestines are crowded into the upper abdomen. This helps explain why gallbladder disease is relatively common during pregnancy and why the symptoms can present in an unusual location, sometimes higher or more lateral than a textbook description would predict. The diaphragm is also pushed upward by up to several centimeters in late pregnancy, which reduces lung capacity and can contribute to a feeling of breathlessness or chest tightness.

Conditions That Commonly Cause Pain in This Area

Given the number of organs stacked under and behind the right breast, the list of conditions that can cause pain there is long. Some of the most common include:

Costochondritis: Inflammation of the cartilage joining a rib to the sternum. Produces localized, reproducible tenderness that worsens with movement or pressure. It is benign but can be alarming because the pain feels like it is inside the chest.
Gallstones: Solid deposits in the gallbladder that can block the bile duct, causing intense, episodic pain in the right upper quadrant, often after meals.
Pleurisy: Inflammation of the pleural lining around the lung, causing sharp pain that worsens with each breath.
Hepatitis or liver swelling: Viral hepatitis, alcoholic liver disease, or congestive heart failure can enlarge the liver and stretch its capsule, producing a deep ache under the right rib cage.
Kidney stones: Stones in the right kidney or ureter can cause flank pain that radiates forward to the area under the breast.
Peptic ulcer disease: Ulcers in the duodenum can refer pain to the right chest wall, sometimes mimicking a chest or breast problem.⁵
Pneumonia: Infection in the right lower lobe of the lung can cause pain in the lower right chest, particularly if the infection irritates the pleura.

Less common causes include pulmonary embolism, rib fractures (sometimes stress fractures that develop gradually), shingles affecting the thoracic nerves, and, rarely, tumors in any of the organs in this region. Heart-related causes are less typical on the right side than the left, but they are not impossible, which is why unexplained chest pain always warrants medical evaluation.

Right Side Versus Left Side

The anatomy under the left breast is noticeably different from the right. The heart sits mostly behind and slightly to the left of the sternum, so the left breast overlies the heart and left lung. The stomach and spleen occupy the left upper quadrant of the abdomen rather than the right. This asymmetry means that the differential diagnosis for pain under the right breast barely overlaps with the differential for pain on the left. Right-sided pain is far more likely to involve the liver, gallbladder, or right kidney, whereas left-sided pain raises concerns about the heart, spleen, or stomach.

The liver’s dominance of the right upper quadrant is the biggest anatomical difference. There is no comparably large solid organ on the left side. The spleen, which sits in the left upper quadrant, is much smaller and more posteriorly located. This is one reason that right upper quadrant ultrasound is such a common and informative diagnostic test: the region is dense with organs that can be visualized through that acoustic window, including hepatic, biliary, renal, adrenal, and gastrointestinal structures.²

When Breast Tissue Itself Is the Source

Not every pain felt “under the right breast” comes from the organs beneath it. The breast itself can hurt. Cyclical breast pain tied to hormonal fluctuations is common and tends to affect both sides, but it can be one-sided or more pronounced on the right. Noncyclical breast pain, which is unrelated to the menstrual cycle, can sometimes be traced to a cyst, fibroadenoma, or localized area of inflammation within the breast tissue. Infections like mastitis, while most common during breastfeeding, can occasionally occur outside of lactation and cause localized pain, redness, and swelling.

Musculoskeletal pain originating from the chest wall is frequently misattributed to the breast because the two are so closely layered. If pressing on a specific spot on the rib cage reproduces the pain, the cause is more likely in the chest wall than in the breast tissue or any deeper organ. Knowing whether the pain changes with breathing, eating, movement, or pressure helps narrow down which layer is involved, and that distinction often determines whether you end up seeing a pulmonologist, a gastroenterologist, or a surgeon.