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Abdominal quadrants and organs: the four quadrants and nine regions

The four quadrants cross at the navel, which Gray's Anatomy places level with the disc between the third and fourth lumbar vertebrae.

The four abdominal quadrants are the right upper, left upper, right lower and left lower. One vertical line down the midline and one horizontal line through the navel make them. The liver and gallbladder lie in the right upper quadrant, and the stomach and spleen in the left upper. The appendix lies in the right lower quadrant and the sigmoid colon in the left lower. The nine abdominal regions divide the same area more finely, with two horizontal and two vertical lines.

How the four quadrants are drawn

Basic Human Anatomy divides the abdomen into four quadrants using the median plane and the umbilicus, the navel. The median plane is a vertical plane through the midline of the body that divides it into right and left halves (SEER training modules). One horizontal line through the navel completes the cross.

The navel is a variable landmark. Gray's Anatomy (1918 edition) places it level with the disc between the third and fourth lumbar vertebrae. Basic Human Anatomy, the Dartmouth medical textbook, says it usually lies between the L3 and L5 levels and that its position is highly variable.

Right and left are the patient's own (Open RN, Medical Terminology 2e). The right upper quadrant is on the patient's right, which is the left side of the picture for someone facing them. The same rule applies to every list of organs on the right and left side of the body. The organ locator shows which organ sits where on a 3D body, by side and by region.

Organs in each of the four quadrants

The liver marks the right upper quadrant, the stomach the left upper, the appendix the right lower and the sigmoid colon the left lower.
Quadrant Organs
Right upper (RUQ) Right lobe of the liver, gallbladder, right kidney, head of the pancreas, most of the duodenum, right bend of the colon
Left upper (LUQ) Stomach, spleen, body and tail of the pancreas, left kidney, left lobe of the liver, left bend of the colon
Right lower (RLQ) Cecum, appendix, start of the ascending colon, loops of ileum, right ureter, right ovary and uterine tube
Left lower (LLQ) Lower end of the descending colon, sigmoid colon, loops of small intestine, left ureter, left ovary and uterine tube

The transverse colon crosses the abdomen on the line between the epigastric and umbilical regions, and it reaches the left bend under the spleen (Gray's). An empty bladder lies entirely within the pelvis, and a full one rises past the top of the pubic bone into the lower abdomen (Gray's). The National Institute of Diabetes and Digestive and Kidney Diseases places the gallbladder in the upper right abdomen, under the liver, and the appendix in the lower right. The SEER training modules place the spleen in the upper left abdominal cavity. The organ locator can open the 3D view on the appendix.

Why quadrant lists differ between textbooks

Several organs cross a line or lie deep at the back, so two correct lists can differ.

Open RN's Medical Terminology 2e leaves the kidneys out of its quadrant lists and lists the ureters in the lower quadrants. The kidneys sit at the back of the abdomen. Gray's puts the upper end of each kidney level with the upper border of the twelfth thoracic vertebra and the lower end level with the third lumbar vertebra. Both ends are higher than the navel, so the kidneys belong to the upper quadrants.

Open RN lists the pancreas in the left upper quadrant. Gray's places its head in the curve of the duodenum, to the right of the midline, and its tail in the upper left. The gland therefore spans both upper quadrants.

The liver crosses the midline too. Open RN lists its right lobe in the right upper quadrant and its left lobe in the left upper.

One organ in both systems: the stomach

SEER, the training program of the US National Cancer Institute, places the stomach in the upper left quadrant. In the nine-region grid, Gray's spreads it across three regions: the epigastric, the umbilical and the left hypochondriac.

Gray's also gives the two ends of the stomach in numbers. The inlet lies about 2.5 cm to the left of the breastbone, behind the seventh rib cartilage. The outlet, the pylorus, lies about 1 cm to the right of the midline. A "left side" organ therefore ends just on the right.

How the nine regions are drawn

Two horizontal lines and two vertical lines make a grid of nine squares. Gray's describes two ways of setting the lines.

The older method uses the subcostal line, level with the lowest points of the tenth rib cartilages. Its lower line passes through the tubercles on the crests of the hip bones.

The second method, Addison's, starts with the transpyloric line. That line lies halfway between the notch at the top of the breastbone and the top of the pubic bone. It is level with the first lumbar vertebra. The lower line, the transtubercular, lies midway between the transpyloric line and the pubic bone, level with the fifth lumbar vertebra. Addison's vertical lines run halfway between the midline and the front point of each hip bone.

The top row holds the right hypochondriac, epigastric and left hypochondriac regions. The middle row holds the right lumbar, umbilical and left lumbar regions. The bottom row holds the right iliac, hypogastric and left iliac regions. Gray's also calls the hypogastric region pubic and the iliac regions inguinal.

Organs in each of the nine regions

Gray's Anatomy spreads the stomach over three of the nine regions and the cecum over two, the right iliac and the hypogastric.
Region Position Organs
Right hypochondriac Upper right Right lobe of the liver, gallbladder, right bend of the colon
Epigastric Upper middle Liver, stomach, pancreas, upper end of the spleen
Left hypochondriac Upper left Stomach, spleen, tail of the pancreas, left bend of the colon, tip of the liver's left lobe
Right lumbar Middle right Ascending colon, loops of ileum
Umbilical Center Part of the stomach, transverse colon, duodenum, loops of jejunum and ileum
Left lumbar Middle left Descending colon, loops of jejunum
Right iliac Lower right Cecum, appendix, loops of ileum
Hypogastric Lower middle Loops of ileum, part of the cecum, top of a full bladder
Left iliac Lower left End of the descending colon, loops of jejunum

The organs follow the regions Gray's assigns under Addison's lines.

The kidneys sit behind the grid and straddle its lines. In Gray's surface outline, the transpyloric line crosses each kidney at its hilum, the notch on its inner edge, 5 cm from the midline. Two thirds of each kidney lies on the inner side of the vertical line.

Why two systems exist

Gray's says the nine regions exist for convenience in describing the organs and in referring to disease in them. Basic Human Anatomy treats the quadrants as the customary system and notes that the older region names may still be encountered.

A quadrant or a region only names a place. Linking a pain there to an organ takes an examination by a doctor or nurse.

Try it on a figure

Organs of the bodyWhich organ sits where, by side and by region.3D human anatomyEvery system of the body, one part at a time.Organs on the right and left side of the body, level by levelThe liver, gallbladder, cecum and appendix sit on the right; the stomach, spleen and sigmoid colon on the left. Each side by level, front and back.Where is the liver located? Under the right ribs, mostly right of the midlineThe liver sits under the right ribs, from the fifth rib cartilage to the rib margin, and ends about 5 cm left of the midline. Size, weight and lobes.

Questions people ask

What organs are in each of the four abdominal quadrants?

The right upper quadrant holds the liver's right lobe, the gallbladder and the right kidney. The left upper holds the stomach, the spleen, the body and tail of the pancreas and the left kidney. The right lower holds the cecum, the appendix and the ascending colon. The left lower holds the descending and sigmoid colon. Each lower quadrant also holds a ureter and, in females, an ovary and uterine tube.

What are the nine regions of the abdomen?

From the patient's right to left, the top row is the right hypochondriac, epigastric and left hypochondriac regions. The middle row is the right lumbar, umbilical and left lumbar regions. The bottom row is the right iliac, hypogastric and left iliac regions.

Where is the line between the upper and lower quadrants?

At the navel. Gray's Anatomy places the navel level with the disc between the third and fourth lumbar vertebrae. Basic Human Anatomy says it usually lies between the L3 and L5 levels and that its position is highly variable.

Which quadrant is the pancreas in?

Open RN's Medical Terminology 2e lists the pancreas in the left upper quadrant. Gray's Anatomy places its head in the curve of the duodenum, to the right of the midline, so the gland spans both upper quadrants.

Which quadrant are the kidneys in?

The upper quadrants, at the back of the abdomen. Gray's Anatomy puts the upper end of each kidney level with the twelfth thoracic vertebra and the lower end level with the third lumbar vertebra, the right kidney usually slightly lower. That is higher than the navel, which Gray's Anatomy places at the disc between the third and fourth lumbar vertebrae.

Why are there two ways to divide the abdomen?

Gray's Anatomy says the nine regions exist for convenience in describing the organs and in referring to disease in them. Basic Human Anatomy treats the quadrants as the customary system and notes that the older region names may still be encountered.

8 sources
  1. Medical Terminology 2e, section 2.4: Body Regions, Open RN, WisTech Open. Accessed 14 November 2026.
  2. SEER Training Modules: Anatomical Terminology, National Cancer Institute, US National Institutes of Health. Accessed 14 November 2026.
  3. SEER Training Modules: Spleen, National Cancer Institute, US National Institutes of Health. Accessed 14 November 2026.
  4. Definition & Facts for Appendicitis, National Institute of Diabetes and Digestive and Kidney Diseases. Accessed 14 November 2026.
  5. Symptoms & Causes of Gallstones, National Institute of Diabetes and Digestive and Kidney Diseases. Accessed 14 November 2026.
  6. SEER Training Modules: Stomach, National Cancer Institute, US National Institutes of Health. Accessed 14 November 2026.
  7. Anatomy of the Human Body, 20th edition (1918): The Abdomen, The Pancreas, The Large Intestine, The Urinary Organs, The Urinary Bladder, and Surface Markings of the Abdomen, Henry Gray, revised by Warren H. Lewis; Lea and Febiger (scan held by the Internet Archive). Accessed 14 November 2026.
  8. Basic Human Anatomy, chapter 25: Abdominal walls, O'Rahilly, Müller, Carpenter and Swenson; Dartmouth Medical School. Accessed 14 November 2026.

By the Body Visualizer 3D team. The dividing lines, their landmarks and the organ lists were taken from the anatomy references listed and matched against each reference's own wording. Where the books draw a line or list an organ differently, each version is shown with its source.

First published 14 November 2026. Last updated 14 November 2026. How pages here are made is in the editorial policy.