Expansion
At L1, halfway between the suprasternal notch and the pubic symphysis
Mnemonic
Transpyloric plane of Addison, at L1, halfway between the jugular notch and the pubic symphysis, roughly a hand’s breadth below the xiphisternum.
Structures at this level:
- Pylorus of the stomach
- Neck of the pancreas, and the origin of the portal vein behind it
- Fundus of the gallbladder, at the tip of the ninth costal cartilage
- Hila of both kidneys, the left slightly above and the right slightly below
- Origin of the superior mesenteric artery
- Duodenojejunal flexure
- End of the spinal cord (conus medullaris)
- Second part of the duodenum, and the root of the transverse mesocolon
“L1 is the busiest plane in the abdomen”, which is why it is worth learning as a single list rather than as separate facts.
Expansion
Located at the level of L1, midway between the suprasternal notch and the pubic symphysis (or roughly a hand’s breadth below the xiphisternum). Structures at this level:
- Pylorus of the stomach
- Fundus of the gallbladder, at the tip of the ninth costal cartilage
- Neck of the pancreas
- Origin of the superior mesenteric artery
- Formation of the portal vein, behind the neck of the pancreas
- Hila of the kidneys - right just below, left just above
- Duodenojejunal flexure
- Termination of the spinal cord (conus medullaris) in the adult
- Root of the transverse mesocolon
Like the sternal angle in the thorax, it is worth learning this as a single list because it answers many questions at once.