Body planes are defined as a two-dimensional surface. Any two whose points can be joined by a straight line that lies entirely in the surface.
From Your Instructor: In describing and discussing human anatomy, we use the terms superior to indicate towards the head, inferior to indicate towards the ground, anterior to indicate towards the front and posterior to indicate towards the back. Since dogs and cats are quadrupeds (therefore “horizontal” to the ground), these terms can get confusing. You may find yourself wondering “Is superior towards the sky (dorsal), or towards the head (cranial)?” Thus, we rarely use superior and inferior, and when we use anterior or posterior, it ends up being equivalent to cranial (towards the head) and caudal (towards the tail).