Vitruvian Man

Shortly after the creation of the zeigot, the hips form. Very shortly after, when the hips form the front of the hip the pelvis becomes a universal fixed point. no matter what happens in the body the center of the front of the pelvis remains in the same place, the rest of the bones move and expand but the front of the pelvis remains the same.

That fixed point from a few dozen cells to the last breath remain in the same position. No matter if the person weights very little of is the heaviest human to ever live, the front of the pelvis stays the same.

That means the front of the pelvis is a fixed point to measure to and from for the rest of the cells in the body from when it forms forward to the body no longer exists

Male or female the location of the front of the pelvis remains the same. Even trans, hermaphrodite, etc. that bone remains.

Use the Compass and identify the location of the body fixed location body parts based on the compass and its associated letters.

That is how to read with the compass the bumps and fixed points.