Abdominal regions and quadrants: what lies under each !

Topic

Imaginary lines divide the abdomen into four quadrants or nine regions, so you can say where it hurts and which organ may be involved.

Updated 2026-11-01

See it in 3D: Liver · Stomach · Appendix · Sigmoid colon · Gallbladder · Spleen · Pancreas · Kidneys · Cecum · Ascending colon · Transverse colon · Descending colon · Duodenum · Urinary bladder

What it is

To describe a pain, a mass or a finding precisely, the abdominal wall is divided by imaginary lines. The four-quadrant system, with two lines crossing at the umbilicus, is the one most used in practice; the nine-region system is more detailed. Knowing which organs project onto each zone shapes the differential diagnosis from the first touch.

Key facts

Right upper quadrant: liver, gallbladder, duodenum, head of pancreas, hepatic flexure, right kidney.
Left upper quadrant: stomach, spleen, tail of pancreas, splenic flexure, left kidney.
Right lower quadrant: cecum, appendix, terminal ileum, right ureter; in women, the right ovary and tube.
Left lower quadrant: sigmoid and descending colon, left ureter; in women, the left ovary and tube.
Lower midline: bladder and, in women, the uterus.

Structure

Vertical lines: the midclavicular lines, continued down to about the midpoint of the inguinal ligament.
Upper horizontal line: the subcostal line joining the lowest points of the costal margin; the lower one joins the tubercles of the iliac crests.
Top row: right hypochondrium, epigastrium, left hypochondrium. Middle row: right flank (lumbar), umbilical region, left flank. Bottom row: right iliac fossa, hypogastrium, left iliac fossa.
The kidneys and pancreas are retroperitoneal: they project onto the front wall, but their pain is often felt in the flank or back.

The nine regions and the organs that project onto each (adult, lying supine).

Region	Main organs	Examples of pain here
Right hypochondrium	Right lobe of liver, gallbladder, hepatic flexure, upper pole of right kidney	Cholecystitis, biliary colic, hepatitis
Epigastrium	Stomach, left lobe of liver, duodenum, pancreas, abdominal aorta	Peptic ulcer, pancreatitis, early appendicitis
Left hypochondrium	Spleen, gastric fundus, tail of pancreas, splenic flexure, upper pole of left kidney	Splenomegaly, splenic infarct or rupture
Right flank (lumbar)	Ascending colon, right kidney, small bowel loops	Renal colic, pyelonephritis
Umbilical	Jejunum and ileum, transverse colon, horizontal duodenum, aorta	Bowel obstruction, early appendicitis, aortic aneurysm
Left flank (lumbar)	Descending colon, left kidney, small bowel loops	Renal colic, diverticulitis
Right iliac fossa	Cecum, appendix, terminal ileum, right ureter, right ovary and tube	Appendicitis, ectopic pregnancy, ovarian torsion
Hypogastrium (suprapubic)	Bladder, uterus, sigmoid colon, rectum	Urinary retention, cystitis, pelvic inflammatory disease
Left iliac fossa	Sigmoid colon, left ureter, left ovary and tube	Diverticulitis, ectopic pregnancy

Test yourself

Think of the answer, then tap the question to see it.

Which lines define the nine abdominal regions?

Two vertical midclavicular lines and two horizontal lines: the subcostal line below the costal margin and the line joining the tubercles of the iliac crests.

In which region do the cecum and appendix project?

The right iliac fossa (right lower quadrant), where McBurney point lies.

Why is early appendicitis pain felt around the umbilicus?

At first it is visceral pain, poorly localized to the midline according to the gut's embryonic segment; it settles in the right iliac fossa only once the parietal peritoneum is irritated.

Which retroperitoneal organs project onto the flanks?

The kidneys, together with the ascending colon on the right and the descending colon on the left; their pain often spreads to the back.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: 1.6 Anatomical Terminology - Anatomy and Physiology 2e | OpenStax (OpenStax, Rice University, 2022); Abdominal examination (Wikipedia, 2026); Evaluation of the Gastrointestinal Patient - Gastroenterology - Merck Manual Professional Edition (Merck & Co., Inc., 2025).

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Representative model, for educational purposes only.