Standard anatomical position

In medical disciplines, all references to a location on or in the body are made based upon the standard anatomical position.

This is a good approximation to the position in which the skull would be if the subject were standing upright and facing forward normally.

It was decided that a plane passing through the inferior margin of the left orbit (the point called the left orbitale) and the superior margin of each ear canal or external auditory meatus, a point called the porion, was most nearly parallel to the surface of the earth at the position the head is normally carried in the living subject.

The formal definition specifies only the three points listed above, sufficient to describe a plane in three-dimensional space.

For dogs, the standard anatomical position is having the abdomen ventral by each paw standing on the supporting surface.