Umbilical plane

The umbilical plane is the transverse plane passing through the umbilicus.

Umbilical plane
The main anatomical planes of the human body, including median (red), parasagittal (yellow), frontal or coronal plane (blue) and transverse or axial plane (green). In this case, the transverse plane is an umbilical plane because it passes through the navel.
umbilicus
Anatomical terminology

This is similar to the location of the mid-transverse plane, which is the transverse plane made through the waist, into roughly two halves: the torso, arms and head on the top, and the pelvis and legs (including hands if arms are held vertically) at the bottom. That is the plane seen in the picture.