Transpyloric plane

Anatomical plane

The transpyloric plane, also known as Addison's plane, is an imaginary horizontal plane, located halfway between the suprasternal notch of the manubrium and the upper border of the symphysis pubis at the level of the first lumbar vertebrae, L1. It lies roughly a hand's breadth beneath the xiphisternum or midway between the xiphisternum and the umbilicus.

The transpyloric plane is clinically notable because it passes through several important abdominal structures. It also divides the supracolic and infracolic compartments, with the liver, spleen and gastric fundus above it and the small intestine and colon below it.

The transpyloric plane passes through the pylorus of the stomach, despite it being suspended by the lesser and greater omentum and being relatively mobile.

The horizontal part of the duodenum slopes upwards to the left of the vertical midline, following which the vertical ascending part of the duodenum reaches the transpyloric plane. It ends in the duodenojejunal junction, which lies approximately 2.5 cm to the left of the midline and just below the transpyloric plane.

The fundus of the gallbladder projects from the liver's inferior border at the intersection of the transpyloric plane and the right lateral midline.

The lower border of the spleen lies near the transpyloric plane. Addison reported his findings in a paper titled, "On the anatomical topography of the abdominal viscera in man, especially the gastro intestinal canal" in which he established a baseline for the anatomy of the abdomen based on the arrangement of the map of the Earth. Using the suprasternal notch as the North Pole of the trunk, and the upper border of the pubic symphysis as the South Pole, he drew a vertical line joining these two points as his meridian. At the meridian's midpoint, he then drew a perpendicular line corresponding to the Equator. As this transverse plane crossed the pylorus, he called it the transpyloric plane.