ABDOMINAL CAVITY: ANATOMY AND ORGANS, FUNCTIONS - ANATOMY AND PHYSIOLOGY - 2025

The abdominal cavity is the body space that the region of the abdomen occupies, located between the diaphragm and the opening of the pelvis. It is the largest cavity in the human body and contains the main organs of the digestive, urinary and genital systems.

For its study and clinical evaluation in the field of medicine, the abdomen must be topographically divided externally into 9 quadrants or regions, using four imaginary lines, two vertical and two horizontal.

There are nine clearly delimited quadrants, each with its own name for your reference, which are from top to bottom and from right to left:

• Upper quadrants (3): Right hypochondrium, epigastrium, left hypochondrium.
• Middle quadrants (3): right flank, mesogastrium, left flank.
• Lower quadrants (3): right iliac fossa, hypogastrium, left iliac fossa.

Anatomy and organs

The abdominal cavity is separated from the thorax by the thoracic diaphragm muscle.

Each quadrant has a content that facilitates the study of symptoms to establish a diagnosis.

Right hypochondrium

It is the quadrant that is under the ribs or the costal margin on the right side.

In this quadrant are located the liver with its gallbladder, part of the large intestine called the hepatic flexure of the colon, as well as the right kidney backwards with its respective adrenal gland.

The cystic point, one of the most clinically important points in terms of localized pain in the right upper quadrant, is the site where it intersects with the lower right costal margin, an imaginary diagonal line that runs from the umbilicus.

When pressing the cystic point, if you wake up intense pain and stop breathing when trying a deep inspiration. It is called a positive Murphy's sign, which consists of an inflammation of the gallbladder.

Epigastrium

This quadrant that occupies the superomedial part of the abdomen, goes from the xiphoid process to the navel and includes part of the stomach, duodenum, pancreas and the solar plexus.

Epigastralgia is one of the most frequent abdominal pain, and its main causes are gastric in origin.

Indigestion, gastroesophageal reflux, dyspepsia, peptic or duodenal ulcer, are pathologies whose symptoms are based on a burning sensation, the patient reports that the epigastrium "burns".

Its evaluation consists mainly of anamnesis of the patient, palpation and auscultation.

Left hypochondrium

Like its contralateral namesake, it is located under the ribs on the left side. The viscera contained in this quadrant are the spleen, the tail of the pancreas, the splenic flexure of the colon, and the left kidney with the adrenal gland on the same side.

Kidney pain is one of the most frequent reasons for consultation for pain in the hypochondria or the lumbar region.

Bimanual palpation, or Guyon's method, is performed with the patient in a supine position with the knees slightly bent. One hand is placed in the lumbar fossa and the other at the level of the flank in front.

Next, pressure is applied with the hand placed on the flank and an attempt is made to feel the "ball" between the lumbar region and the flank.

The percussion fist maneuver, on the other hand, consists of a light tapping with the fist in the lumbar region, on the site where the kidney is located.

Right side

The ascending portion of the colon, the right ureter, and part of the thin intestinal loops are located in this space, which is also called the “vacuum region”.

Pain in this area mainly represents colon inflammations due to various causes, as well as ureteral pain due to descending stones.

Mesogastrium

Refers to the center of the abdomen. Its content consists mainly of the transverse colon, and part of the small intestinal loops.

Mesogastric pains are generally deferred from other abdominal visors and structures, however, colicky pain in the periumbilical region indicates small bowel pathology.

Left flank

Like its contralateral namesake, the left flank is also known as the "abdominal void region." The descending portion of the colon, part of the intestinal loops, and the left ureter are located in this space.

The clinical implications are similar from one flank to the other, being important to correctly delimit the evaluated spaces to establish an adequate diagnosis.

Right lower quadrant

Acute pain in the right iliac fossa is one of the quadrants that represents one of the main reasons for consultation in the emergency service.

Its content is represented by the cecum with its cecal appendix and in female patients the uterine annexes (ovaries and fallopian tubes).

McBurney's appendicular point is located on an imaginary line drawn from the umbilicus to the right iliac crest at the exact point where the upper two thirds of that line meet with the lower third.

The MCBurney point is considered a positive maneuver for acute appendicitis, when pressing on it produces a sharp pain that makes the patient scream.

Hypogastrium

In the hypogastrium is the urinary bladder, and part of the thin loops and in female patients the uterus is also located.

Hypogastric pain is mainly consulted in the area of ​​gynecology, however, in cases of decreasing kidney stones it can also be consulted with hypogastric pain.

Left iliac fossa

In the left iliac fossa, like the contralateral homonymous quadrant, the sigmoid colon is located and in female patients the left uterine annexes (ovaries and fallopian tubes).

Function of the abdominal cavity

Its function is to contain and hold the abdominal viscera, without being rigid like the thorax, to allow peristaltic and diaphragmatic movements in the functions of swallowing, digestion and respiration.

The peritoneum, a serous membrane with two sheets, a parietal sheet that covers the abdominal cavity and a visceral sheet that covers each of the organs, forming folds and compartments for each one of them, supports the organs without limiting them to allow a optimal irrigation and innervation.

References

1. Agustín Caraballo. Clinical examination manual. University of the Andes. Publications Council. Examination of the abdomen. P. 119-133.
2. Latarjet Ruiz Liard. Human anatomy. 4th Edition. Volume 2. Editorial Médica Panamericana.
3. William C. Shiel Jr. Abdominal Pain: Symptoms & Signs. Recovered from: medicinenet.com
4. Roger Sherman. Chapter 86. Abdominal pain. Clinical methods: The history, physical, and laboratory examinations. 3rd Edition. Recovered from: ncbi.nlm.nih.gov
5. Alexandra Stanislavsky. Abdominal cavity. Recovered from: radiopaedia.org