Your abdomen is divided into four quadrants by two imaginary lines that cross at your belly button: one vertical line running down the middle of your body and one horizontal line across it. This creates the right upper quadrant (RUQ), left upper quadrant (LUQ), right lower quadrant (RLQ), and left lower quadrant (LLQ). Each quadrant contains a distinct set of organs, and knowing which organs sit where helps explain why pain in a specific area often points to particular conditions.
Note that “right” and “left” refer to the patient’s own right and left sides, not a mirror image.
Right Upper Quadrant (RUQ)
The right upper quadrant is dominated by the liver, specifically its large right lobe. Tucked just beneath the liver is the gallbladder, a small sac that stores bile used in fat digestion. This quadrant also contains the first section of the small intestine (the duodenum), the head of the pancreas, and the lower end of the stomach where it empties into the intestine.
Behind these organs, deeper in the back of the abdomen, sit the right kidney and its small cap of adrenal gland tissue. Part of the large intestine runs through here too: the upper portion of the ascending colon makes a sharp turn (the right colic flexure) and continues as the right half of the transverse colon.
Pain in the RUQ is commonly linked to gallbladder problems like gallstones or gallbladder inflammation. Liver conditions such as hepatitis or a liver abscess can also produce RUQ pain. Kidney stones on the right side often cause pain that radiates from this area toward the back and flank.
Left Upper Quadrant (LUQ)
The left upper quadrant houses the stomach (the main body of it), the spleen, and the tail of the pancreas. The spleen sits tucked under the lower ribs on the left side and filters blood. Behind these organs, the left kidney and left adrenal gland occupy the deeper retroperitoneal space. The left half of the transverse colon and the beginning of the descending colon pass through this quadrant as well.
LUQ pain has a broader list of possible causes. Gastritis and stomach ulcers are common culprits. Inflammation of the pancreas (pancreatitis) can produce severe pain here that often radiates to the back. Because of the quadrant’s proximity to the chest, heart-related conditions like angina or even a heart attack can sometimes present as upper left abdominal pain, which is why clinicians take LUQ pain seriously even when the cause seems digestive.
Right Lower Quadrant (RLQ)
The right lower quadrant is best known for the appendix, a small finger-shaped pouch attached to the cecum, which is the very beginning of the large intestine. The cecum and the lower portion of the ascending colon also sit here, along with a section of the small intestine. The surface landmark used to locate the appendix is called McBurney’s point, found about one-third of the way along a line drawn from the right hip bone to the belly button.
In women, the right ovary and right fallopian tube are located in this quadrant. A small portion of the bladder and, in women, part of the uterus also extend into this region. The right iliac artery, a major blood vessel supplying the leg, runs through here as well.
RLQ pain is the classic presentation for appendicitis, which often starts as vague discomfort around the belly button before migrating to the lower right. Other conditions that cause pain here include inflammatory bowel disease, irritable bowel syndrome, and colon inflammation. In women, ovarian cysts, ovarian torsion, ectopic pregnancy, and pelvic inflammatory disease are all possible causes of right lower quadrant pain.
Left Lower Quadrant (LLQ)
The left lower quadrant contains the lower portion of the descending colon and the sigmoid colon, an S-shaped segment that connects to the rectum. Like the right side, this quadrant also holds a section of small intestine and, in women, the left ovary and left fallopian tube. Part of the bladder and uterus can extend into this region as well.
Diverticulitis is the condition most closely associated with LLQ pain. It occurs when small pouches in the colon wall become inflamed or infected, and in Western populations these pouches form most often in the sigmoid colon. Colitis, irritable bowel syndrome, and kidney stones on the left side also cause pain here. In women, the same gynecologic conditions that affect the RLQ (ectopic pregnancy, ovarian cysts, torsion) can mirror on the left side.
Structures That Span Multiple Quadrants
Several organs don’t fit neatly into one quadrant. The small intestine loops extensively through all four quadrants but is most concentrated in the central and lower abdomen. The transverse colon crosses the upper abdomen from right to left. The pancreas stretches from the RUQ (its head) through the midline to the LUQ (its tail). The bladder and uterus sit low and central, straddling the line between the two lower quadrants.
Major blood vessels also run through the center. The abdominal aorta travels along the spine, slightly left of the midline, before splitting into two branches (the common iliac arteries) near the level of the belly button. The inferior vena cava, the body’s largest vein, runs along the right side of the spine, carrying blood back to the heart. Because these vessels sit behind the organs, they aren’t typically associated with quadrant-specific pain, but conditions like an aortic aneurysm can produce deep abdominal or back pain.
The Nine-Region Alternative
Doctors sometimes use a more detailed map that divides the abdomen into nine regions instead of four. This grid is created by four lines: two vertical lines dropping from the midpoint of each collarbone, and two horizontal lines, one at the bottom of the ribs and one at the top of the hip bones. The result is nine boxes with names like the epigastric region (upper center, over the stomach), the umbilical region (around the belly button), and the hypogastric region (lower center, over the bladder).
The nine-region system is more precise for pinpointing organ locations, but the four-quadrant model remains the standard shorthand in emergency and primary care settings because it’s faster and easier to communicate. If you’re describing pain to a doctor, pointing to the correct quadrant is a useful first step that immediately narrows the list of likely causes.