The word "
dorsal" originates from
Old French dorsalis, which in turn is from
Latin , meaning "the
back". This is as opposed to the term "
ventral", which is
etymologically from Latin or meaning "
belly,
stomach". In
anatomical and
embryological nomenclatures, "dorsal" refers to structures more towards the side of the embryonic
epiblast, and "ventral" more towards the
hypoblast side,
regardless of the organism's posture and physical orientation. Other terms such as "
anterior", "
posterior", "front", "back" and so on are
body relative directions that are also often used, sometimes to describe a ventral-dorsal relationship among an organism's structures. Such terms are based on an
frame of reference of where the subject is facing, and their meanings are
dependent on the organism's current posture and orientation. • In
bipedal organisms with
upright posture, "dorsal" is often
synonymous with "posterior", "back" or "rear", and "ventral" with "anterior" or "front", in reference to the direct the organism is facing. • In
quadrupedal organisms that walk and stand on four limbs, the dorsal surface is often the top surface, and the ventral surface is the bottom (or lower) surface, as their torso is often orientated in a horizontal (or slightly slanted)
prone position. The term "anterior" is synonymous with "
rostral" (towards the
nose) or "
cranial" (towards the
head), while "posterior" means "
caudal" (towards the
tail). ==See also==