The medical community often uses an organized system of anatomical division to accurately pinpoint the location of internal structures, especially within the torso. This system divides the abdomen into four imaginary quadrants created by a vertical and a horizontal line crossing at the navel. The four sections are the Right Upper Quadrant (RUQ), Left Upper Quadrant (LUQ), Right Lower Quadrant (RLQ), and Left Lower Quadrant (LLQ). While this categorization is helpful for diagnosis and communication, it is important to understand that many organs do not fit neatly into one box. This overview will focus specifically on the organs whose primary or significant bulk resides on the right side of the body cavity, offering a detailed look at the structures located in the right upper and lower quadrants, as well as the deeper posterior and pelvic regions.
The Right Upper Quadrant: Liver and Gallbladder
The Right Upper Quadrant (RUQ) is largely defined by the presence of the liver, which is the body’s largest internal organ and gland. This massive organ is situated directly beneath the diaphragm and is mostly shielded by the lower right rib cage. The liver is divided into two primary lobes, with the much larger right lobe dominating the space within this quadrant. The liver performs over 500 distinct functions, including the regulation of most chemical levels in the blood and the metabolism of drugs. One of its main digestive roles is the production of bile, an alkaline fluid that helps break down fats in the small intestine.
Tucked into an indentation underneath the right lobe of the liver is the gallbladder, a small, hollow organ. The gallbladder’s primary function is to store and concentrate the bile produced by the liver. When fats enter the small intestine, the gallbladder contracts, forcing the concentrated bile into the first part of the small intestine, the duodenum, to aid in digestion. Other structures partially located in the RUQ include the right kidney, the right adrenal gland, and the head of the pancreas. The initial segment of the small intestine, the duodenum, curves around the head of the pancreas in this region. A segment of the large intestine known as the transverse colon also crosses through the upper part of this quadrant.
Lower Abdominal Structures: Appendix and Colon
Shifting to the Right Lower Quadrant (RLQ), the primary structures here are significant components of the gastrointestinal tract, specifically the large intestine. The very beginning of the large intestine, a pouch known as the cecum, is located within the RLQ. The terminal end of the small intestine, the ileum, empties its contents into the cecum through a muscular valve. Attached to the cecum is the vermiform appendix, a narrow, cylindrical tube.
Although the appendix was once considered a vestigial organ, current understanding suggests it may play a role in the immune system and may house beneficial gut flora. The appendix’s location makes it a common source of medical emergencies, as inflammation (appendicitis) often presents with pain localized to the RLQ. Continuing upward from the cecum is the ascending colon, the second part of the large intestine. This segment travels superiorly along the right side of the abdomen toward the liver, absorbing water and electrolytes from the remaining food waste. The RLQ also contains the right ureter and, in biological females, the right ovary and fallopian tube.
Posterior and Pelvic Organs
The full picture of the right side involves organs situated deeper within the body cavity, particularly those in the retroperitoneal space behind the abdominal lining. The right kidney and the right adrenal gland are located in this posterior space. The kidney is a bean-shaped organ responsible for filtering blood and producing urine, and it sits against the back wall of the abdomen.
Capping the superior pole of the right kidney is the right adrenal gland, a small endocrine organ that secretes hormones regulating metabolism, immune function, and blood pressure. Connecting the kidney to the bladder is the right ureter, a muscular tube that transports urine and is also located in the retroperitoneal space before descending into the pelvis. In biological females, the right ovary and right fallopian tube are situated deep within the pelvic cavity on the right side. The ovary is responsible for producing eggs and reproductive hormones, while the fallopian tube provides the pathway for the egg toward the uterus. Finally, structures of the upper body, such as the right lung and the right main bronchus, occupy the right thoracic cavity above the abdomen. The right lung is divided into three lobes.