| Quadrants and regions of abdomen | |
|---|---|
 Side-by-side comparison of the regions (left) and quadrants (right) of the abdomen. | |
| Anatomical terminology |
The human abdomen is divided into quadrants and regions by anatomists and physicians for the purposes of study, diagnosis, and treatment.[1][2] The division into four quadrants allows the localisation of pain and tenderness, scars, lumps, and other items of interest, narrowing in on which organs and tissues may be involved. The quadrants are referred to as the left lower quadrant, left upper quadrant, right upper quadrant and right lower quadrant. These terms are not used in comparative anatomy, since most other animals do not stand erect.
The left lower quadrant includes the left iliac fossa and half of the flank. The equivalent in other animals is left posterior quadrant. The left upper quadrant extends from the umbilical plane to the left ribcage. This is the left anterior quadrant in other animals. The right upper quadrant extends from umbilical plane to the right ribcage. The equivalent in other animals is right anterior quadrant. The right lower quadrant extends from the umbilical plane to the right inguinal ligament. This in other animals is the right posterior quadrant.
The nine regions offer more detailed anatomy and are delineated by two vertical and two horizontal lines.
- ^ Elsevier, Dorland's Illustrated Medical Dictionary, Elsevier.
- ^ Wolters Kluwer, Stedman's Medical Dictionary, Wolters Kluwer.