median sagittal plane
A vertical plane passing through the center of the body (including the navel
and spine), dividing it into equal right and left halves. Planes situated
to one or the other side of the median sagittal plane and parallel to it
are known as sagittal planes or paramedians.
A structure situated nearer to the median plane of the body than another
is said to be medial. Similarly, a structure
that lies farther away from the median plane than another is said to be
lateral to the other.