The ‘axial plane’ is always perpendicular to the longitudinal and the frontal plane of an organism, extremity or organ, dividing it into a dorsal, superior, above or top part, and a ventral, inferior, below or bottom part.
The ‘frontal plane’ is always perpendicular to the axial and longitudinal plane of an organism, extremity or organ, dividing it into an anterior, rostral or front part, and a posterior, caudal or back part.
The ‘longitudinal plane’ is always perpendicular to the axial and frontal plane of an organism, extremity or organ, running parallel to the ‘median plane’ and dividing it into a left and right part.