Organs Located Under the Left Rib Cage
The left rib cage protects several vital organs including the spleen, the left kidney, the stomach (fundus and body), the tail of the pancreas, the splenic flexure of the colon, and the left lung with its pleural space.
Primary Anatomical Structures
Spleen
- The spleen is the most prominent solid organ under the left rib cage, positioned in the left upper quadrant and serving as a key sonographic landmark 1
- It is significantly smaller than the liver and provides a more limited acoustic window for ultrasound imaging 1
- The spleen has multiple ligamentous attachments including the gastrosplenic, colicosplenic, phrenocolic, and phrenosplenic (splenorenal) ligaments 2
- A normal spleen is not palpable below the left costal margin; palpability indicates splenomegaly 3
Left Kidney
- The left kidney is located retroperitoneally in the left upper quadrant, typically above the costal margin in the costovertebral angle region 1
- The kidney's inferior pole is anterior and lateral to its superior pole, lying oblique to standard anatomic planes 1
- The left kidney lacks a hepatic acoustic window for imaging, requiring an intercostal approach between the anterior axillary line and midline posteriorly 1
Stomach
- The fundus and body of the stomach occupy space under the left rib cage 1
- The stomach receives vascular supply from short gastric vessels that run through the gastrosplenic ligament 2
Pancreatic Tail
- The tail of the pancreas extends into the left upper quadrant near the splenic hilum 4
- Pancreatic injuries in this region may be difficult to detect initially and require serial enzyme monitoring 4
Additional Structures
Splenic Flexure of Colon
- The gas-filled splenic flexure and descending colon are positioned under the left rib cage 1
- These structures must be avoided during ultrasound examination by placing the probe on the posterior axillary line or more posteriorly 1
Left Pleural Space
- The left pleural space lies above the diaphragm and can be visualized with superior angulation during ultrasound 1
- This space is examined for hemothorax by looking for anechoic or hypoechoic fluid collections above the diaphragm 1
Anatomical Spaces for Clinical Assessment
The left upper quadrant contains four potential spaces that are clinically significant for fluid accumulation 1:
- Pleural space - above the diaphragm
- Subphrenic space - below the diaphragm, above the spleen
- Splenorenal space - between the spleen and left kidney
- Left paracolic gutter - continuation from the inferior pole of the kidney 1
Clinical Relevance
- The spleen is the most commonly injured organ in blunt abdominal trauma affecting the left upper quadrant 5
- Left upper quadrant injuries may involve the spleen, left kidney, pancreatic tail, or left-sided rib fractures 4
- The left kidney's relationship with the diaphragm, ribs, pleura, and spleen is critical for understanding intrarenal access during minimally invasive procedures 6