Abdominal Regions, Quadrants, and Body Cavities

Abdominal Quadrants and Planes

The abdomen is divided into quadrants for descriptive and diagnostic purposes. These quadrants are defined by two intersecting planes:

  • Median Plane: A vertical plane that divides the body into right and left halves.
  • Transumbilical Plane: A horizontal plane that passes through the umbilicus (navel).

These planes create four quadrants:

  • Right Upper Quadrant (RUQ)
  • Left Upper Quadrant (LUQ)
  • Right Lower Quadrant (RLQ)
  • Left Lower Quadrant (LLQ)

Abdominal Regions

The abdomen can also be divided into nine regions. These regions provide more specific locations for anatomical structures and pain referral patterns:

  • Right Hypochondriac Region: Located on the upper right side of the abdomen, below the ribs.
  • Epigastric Region: The central region of the abdomen, located above the umbilical region and between the right and left hypochondriac regions.
  • Left Hypochondriac Region: Located on the upper left side of the abdomen, below the ribs.
  • Right Lumbar Region: Located on the right side of the abdomen, lateral to the umbilical region.
  • Umbilical Region: The central region of the abdomen, surrounding the umbilicus.
  • Left Lumbar Region: Located on the left side of the abdomen, lateral to the umbilical region.
  • Right Iliac Region: Located on the lower right side of the abdomen, also known as the right inguinal region.
  • Hypogastric Region: Located in the lower central part of the abdomen, below the umbilical region and between the right and left iliac regions.
  • Left Iliac Region: Located on the lower left side of the abdomen, also known as the left inguinal region.

Body Cavities

The body contains several cavities that house and protect internal organs. These cavities can be broadly classified into:

  • Dorsal Body Cavity: Located on the posterior aspect of the body. It consists of:
    • Cranial Cavity: Encloses the brain.
    • Vertebral Cavity: Encloses the spinal cord.
  • Ventral Body Cavity: Located on the anterior aspect of the body. It is further divided into:
    • Thoracic Cavity: Superior to the diaphragm. Contains:
      • Superior Mediastinum
      • Pleural Cavities: Each surrounds a lung.
      • Pericardial Cavity: Located within the mediastinum and surrounds the heart.
    • Abdominopelvic Cavity: Inferior to the diaphragm; sometimes described as two continuous cavities:
      • Abdominal Cavity: Contains the stomach, intestines, liver, and other abdominal organs.
      • Pelvic Cavity: Contains the bladder, reproductive organs, and rectum.