Addison's Plane vs Transpyloric Plane
Addison's plane and the transpyloric plane are the same anatomical landmark. Both terms refer to the horizontal plane that passes through the body at the level of the lower border of the first lumbar vertebra (L1), midway between the suprasternal notch and the pubic symphysis.
Anatomical Definition and Location
- The transpyloric plane (also known as Addison's plane) is a horizontal plane that typically lies at the level of the lower border of L1 or the upper border of L2 1, 2.
- In modern CT imaging studies of living adults, this plane is most commonly found between lower L1 and upper L2 in approximately 75% of individuals 2.
Key Anatomical Structures at This Level
The transpyloric plane is clinically significant because several important structures are located at or near this level:
- Portal vein formation is within this plane in approximately 53-56% of individuals 1, 2.
- Superior mesenteric artery is found at this level in about 56% of cases 2.
- Tip of the ninth rib intersects this plane in approximately 60% of individuals 2.
- Left renal hilum is located at this plane in 54% of cases, though the right renal hilum is typically below it 2.
- The gallbladder fundus is more often below this plane rather than at it 2.
Clinical Considerations and Common Pitfalls
- Age-related variations exist: In pediatric populations, the vertebral levels of major vascular structures vary with age, with younger children showing higher positions for some structures 3.
- Ethnic differences matter: Surface anatomy studies from different populations (Turkish vs. other populations) show some variations in the exact relationships of structures to anatomical planes 1.
- Imaging technique affects measurements: These landmarks are best assessed using CT imaging in supine patients at end-tidal inspiration, as cadaveric studies may not accurately reflect living anatomy 2.
- Individual variation is substantial: The classical textbook descriptions derived from cadaveric studies often do not match the anatomy found in living patients using modern cross-sectional imaging 1, 2.
Practical Application
When using the transpyloric plane (Addison's plane) as a clinical reference:
- It serves as a useful landmark for locating abdominal structures during physical examination and procedures 1, 2.
- The plane is located approximately midway between the xiphoid process and the umbilicus on surface anatomy 4.
- Clinicians should be aware that individual anatomical variation means that structures may not always be exactly at the level described in classical anatomy texts 2.