Organs Located on the Left Side of the Body
The left side of the body contains the spleen, left kidney, stomach, pancreatic tail, descending colon, splenic flexure, and the left lung (with two lobes), while the heart's apex points leftward. 1, 2
Upper Left Quadrant Organs
- Spleen: The primary solid organ in the left upper quadrant, significantly smaller than the liver and providing a limited sonographic window compared to its right-sided counterpart 1
- Left kidney: Located retroperitoneally in the left flank, with its inferior pole anterior and lateral to the superior pole, positioned obliquely along the intercostal spaces 1
- Stomach: Positioned in the left upper abdomen as part of the gastrointestinal tract 2, 3
- Pancreatic tail: The distal portion of the pancreas extends toward the splenic hilum on the left side 4, 5
- Splenic flexure: The bend where the transverse colon transitions to the descending colon, filled with gas and located in the left upper quadrant 1
Lower Left Quadrant Organs
- Descending colon: Runs along the left side of the abdomen, often gas-filled 1
- Left paracolic gutter: A potential space continuous with the splenorenal space, representing the most lateral peritoneal recess on the left 1
Thoracic Structures
- Left lung: Contains only two lobes (versus three on the right) due to space restrictions from the heart 2
- Heart apex: Points to the left, with the heart itself being asymmetrically built and positioned 1, 2, 6
Key Anatomical Spaces on the Left
The left upper quadrant contains four critical potential spaces examined during ultrasound: the pleural space, subphrenic space, splenorenal space, and the inferior pole of the kidney continuing as the left paracolic gutter 1
Clinical Significance
The left-sided organ arrangement (situs solitus) represents the normal biased asymmetry found in vertebrates, with organ positioning being highly conserved and essential for proper function 2, 6. This asymmetric arrangement allows for optimal organ function, such as efficient nutrient retrieval from the long coiled intestine 2.