Underlying organs under abdomen quadrants
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Organs Under the Abdominal Quadrants
The abdomen is divided into 4 quadrants by two planes that intersect at the umbilicus:
- Vertical (median) plane - runs down the midline
- Horizontal (transumbilical) plane - passes through the umbilicus and the L3/L4 intervertebral disc
Organs by Quadrant
Right Upper Quadrant (RUQ)
| Organ | Notes |
|---|---|
| Liver (right lobe, most of it) | Sits under the right dome of the diaphragm; palpable below the costal margin on deep inspiration |
| Gallbladder | Tucked under the inferior surface of the liver |
| Right kidney (upper pole) | Retroperitoneal |
| Duodenum (parts 1-3) | Wraps around the head of the pancreas |
| Head of pancreas | Lies in the curve of the duodenum |
| Right adrenal gland | Retroperitoneal, on top of the right kidney |
| Hepatic flexure of colon | Right colic flexure where ascending colon turns |
| Part of the ascending colon | |
| Part of the transverse colon |
Left Upper Quadrant (LUQ)
| Organ | Notes |
|---|---|
| Stomach | Most of it sits here |
| Spleen | Under the left dome of the diaphragm, protected by ribs 9-11 |
| Left kidney (upper pole) | Retroperitoneal |
| Left adrenal gland | Retroperitoneal |
| Body and tail of pancreas | Retroperitoneal, extending toward the spleen |
| Splenic flexure of colon | Left colic flexure |
| Part of the transverse colon | |
| Part of the descending colon | |
| Liver (left lobe - small portion) |
Right Lower Quadrant (RLQ)
| Organ | Notes |
|---|---|
| Cecum | Beginning of the large intestine |
| Appendix | McBurney's point = 1/3 of the way from the right ASIS to the umbilicus |
| Terminal ileum | The last part of the small intestine |
| Right ureter (mid-section) | Retroperitoneal |
| Right ovary & fallopian tube | In females |
| Right spermatic cord | In males |
| Part of ascending colon |
Left Lower Quadrant (LLQ)
| Organ | Notes |
|---|---|
| Sigmoid colon | S-shaped loop connecting descending colon to rectum |
| Descending colon (lower part) | |
| Left ureter (mid-section) | Retroperitoneal |
| Left ovary & fallopian tube | In females |
| Left spermatic cord | In males |
Midline structures (span multiple quadrants)
- Aorta and inferior vena cava - span upper and lower quadrants along the midline
- Uterus and bladder - when enlarged, project into the lower quadrants
- Small intestine (jejunum & ileum) - fills all four quadrants, predominantly lower
Bonus: Nine-Region Pattern
Clinicians sometimes use a more detailed 9-region system for localizing pain. The abdomen is divided by two horizontal planes (subcostal and intertubercular) and two midclavicular vertical planes:
| Region | Pain Origin |
|---|---|
| Epigastric | Foregut (stomach, duodenum, liver, pancreas) |
| Umbilical | Midgut (small intestine, appendix) |
| Pubic (hypogastric) | Hindgut (sigmoid, rectum, bladder, uterus) |
| Right/Left Hypochondrium | Under the ribs (liver right; spleen left) |
| Right/Left Flank | Kidneys, ureters, ascending/descending colon |
| Right/Left Groin (inguinal) | Appendix/cecum right; sigmoid left; gonads bilaterally |
Clinical relevance: Knowing which organs occupy each quadrant is the foundation of localizing abdominal pain. For example, RUQ pain points toward gallbladder/liver pathology, RLQ pain toward appendicitis, and LLQ toward diverticulitis.
Source: Gray's Anatomy for Students, Fig. 4.185 & 4.186
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