Quadrants and regions of abdomen

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The humanabdomen is divided into quadrants and regions byanatomists andphysicians for the purposes of study,diagnosis, andtreatment.^[1]^[2] The division into four quadrants allows the localisation ofpain andtenderness,scars, lumps, and other items of interest, narrowing in on whichorgans andtissues 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 incomparative anatomy, since most other animals do not stand erect.

Quadrants and regions of abdomen
Side-by-side comparison of the regions (left) and quadrants (right) of theabdomen
Anatomical terminology [edit on Wikidata]

The left lower quadrant includes the leftiliac fossa and half of theflank. The equivalent in other animals isleft posterior quadrant. The left upper quadrant extends from theumbilical plane to the leftribcage. This is theleft anterior quadrant in other animals. The right upper quadrant extends from umbilical plane to the right ribcage. The equivalent in other animals isright anterior quadrant. The right lower quadrant extends from the umbilical plane to the rightinguinal ligament. This in other animals is theright posterior quadrant.

The nine regions offer more detailed anatomy and are delineated by two vertical and two horizontal lines.

Quadrants

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Quadrants of the abdomen

Diagram showing which organs (or parts of organs) are in each quadrant of the abdomen

Theleft lower quadrant (LLQ) of thehuman abdomen is the area left of the midline and below theumbilicus. The LLQ includes the leftiliac fossa and half of the leftflank region. The equivalent term for animals isleft posterior quadrant.Important organs here are:

Theleft upper quadrant (LUQ) extends from themedian plane to the left of the patient, and from theumbilical plane to the left ribcage. The equivalent term for animals isleft anterior quadrant. Important organs here are:

Theright upper quadrant (RUQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right ribcage. The equivalent term for animals isright anterior quadrant. Important organs here are:

Theright lower quadrant (RLQ) extends from the median plane to the right of the patient, and from the umbilical plane to the rightinguinal ligament. The equivalent term for animals isright posterior quadrant. Important organs here are:

Regions

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Regions of abdomen

Regions shown on left in side-by-side comparison with quadrants

Nine regions of the abdomen can be marked using two horizontal and two vertical dividing lines. The vertical lines are themid-clavicular lines taken from the mid-point of eachclavicle. The upper horizontal line is thesubcostal line taken from the inferior parts of the lowest costal cartilages. The lower horizontal line is theextoturbular line connecting thetubercles of the pelvis.^[3]^[4]

The three main centrally positioned regions are theepigastric region, theumbilical region, and thehypogastric region also known as thepubic region.

On the sides of the abdomen the other six regions are the left and righthypochondriac regions, on either side of the epigastrium; the left and rightlumbar flank regions, on either side of the umbilical region, and the left and right iliac oringuinal regions on either side of the hypogastrium.^[3]^[4]

("Hypo-" means below; "epi-" means above; "chondron" means cartilage (in this case, the cartilage of the rib) and "gaster" means stomach. The reversal of "left" and "right" is intentional, because the anatomical designations reflect the patient's own right and left.)

Clinical significance

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Ifabdominal pain or signs ofperitonitis are localised in the LLQ,colitis,diverticulitis,ureteral colic or pain due toovarian cysts orpelvic inflammatory disease may be suspected. Examples of tumors in the left lower quadrant includecolon cancer andovarian tumor.

The LUQ may be painful or tender in the case ofintestinal malrotation. The RUQ may be painful or tender inhepatitis,cholecystitis, andpeptic ulcer. The RLQ, in particular the right inguinal region orright iliac fossa may be painful and tender in conditions such asappendicitis.