The human abdomen is divided into quadrants and regions by anatomists and physicians for the purposes of study, diagnosis, and treatment. The division into four quadrants allows the localisation of

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

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 Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny (the evolution of species). The science began in the classical era, continuing in t ...

, 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 The transumbilical plane or umbilical plane, one of the transverse planes in human anatomy, is a horizontal line that passes through the abdomen at the level of the navel (or umbilicus). In physical examination, clinicians use the transumbilical p ...

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 The inguinal ligament (), also known as Poupart's ligament or groin ligament, is a band running from the pubic tubercle to the anterior superior iliac spine. It forms the base of the inguinal canal through which an indirect inguinal hernia may dev ...

. 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.

Quadrants

The left lower quadrant (LLQ) of the human abdomen is the area left of the midline and below the umbilicus. The LLQ includes the left iliac fossa and half of the left flank region. The equivalent term for animals is ''left posterior quadrant''. Important organs here are: *the

descending colon In the anatomy of humans and homologous primates, the descending colon is the part of the colon extending from the left colic flexure to the level of the iliac crest (whereupon it transitions into the sigmoid colon). The function of the descendin ...

and

sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...

*the left

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

and

fallopian tube The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In ot ...

*the left ureter The left upper quadrant (LUQ) extends from the median plane to the left of the patient, and from the

to the left ribcage. The equivalent term for animals is ''left anterior quadrant''. Important organs here are: * Stomach * Spleen *Left lobe of liver *Body of pancreas *Left kidney and adrenal gland *Splenic flexure of Colon (anatomy), colon *transverse colon, Parts of transverse and

The right 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 is ''right anterior quadrant''. Important organs here are: *Liver *Gall bladder with biliary tree *Duodenum *Head of pancreas *Right kidney and adrenal gland *Hepatic flexure of Colon (anatomy), colon The right lower quadrant (RLQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right

. The equivalent term for animals is ''right posterior quadrant''. Important organs here are: *Cecum *Vermiform appendix, Appendix *Ascending colon *Right

and Fallopian tube *Right ureter

Regions

Nine regions of the abdomen can be marked using two horizontal and two vertical dividing lines. The vertical lines are the mid-clavicular lines taken from the mid-point of each clavicle. The upper horizontal line is the subcostal line taken from the inferior parts of the lowest costal cartilages. The lower horizontal line is the intertubercular line connecting the iliac tubercles, tubercles of the pelvis. The three main centrally positioned regions are the Epigastrium, epigastric region, the umbilical region, and the Hypogastrium, hypogastric region also known as the pubic region. On the sides of the abdomen the other six regions are the left and right hypochondrium, hypochondriac regions, on either side of the epigastrium; the left and right Flank (anatomy), lumbar flank regions, on either side of the umbilical region, and the left and right iliac or Groin, inguinal regions on either side of the hypogastrium. ("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

If abdominal pain or signs of peritonitis are localised in the LLQ, colitis, diverticulitis, ureteral colic or pain due to ovarian cysts or pelvic inflammatory disease may be suspected. Examples of tumors in the left lower quadrant include colon cancer and ovarian tumor. The LUQ may be painful or tender in the case of intestinal malrotation. The RUQ may be painful or tender in hepatitis, cholecystitis, and peptic ulcer. The RLQ, in particular the right inguinal region or iliac fossa, right iliac fossa may be painful and tender in conditions such as appendicitis.

Differential diagnosis

Children *gastroenteritis, mesenteric adenitis, Meckel's diverticulum, Meckel's diverticulitis, intussusception (medical disorder), intussusception, Henoch–Schönlein purpura, lobar pneumonia Adults *regional enteritis, renal colic, perforated peptic ulcer, testicular torsion, rectus sheath hematoma, pelvic inflammatory disease, ectopic pregnancy, endometriosis, torsion/rupture of ovarian cyst, appendicitis Elderly *diverticulitis, intestinal obstruction, colon cancer, colonic carcinoma, mesenteric ischemia, leaking aortic aneurysm

References

{{Superficial abdominopelvic anatomy Abdomen

Quadrants

Regions

Clinical significance

Differential diagnosis

See also

References