What is the medical term meaning from front to back?

It could be ventral to dorsal, anterior to posterior, or even rostral to caudal, depending on the orientation.

I believe the preceding answer is the most correct however, if you're looking for one medical term it could be anteroposterior but that means "relating to both the front and back" and not "front to back".
You can use Anterior/Posterior or Ventral/Dorsal
A posteroanterior