Toward, on, in, or near the back or upper surface or part of an organism.2. Botany Of or on the outer surface, underside, or back of an organ.
3. Relatively near the back as compared with other structures or parts of the same kind which are closer to the front or belly side: In human anatomy, the dorsalis normally equivalent to the posterior area of the body.
4. Etymology: from Middle French dorsal, from Late Latin dorsalis, corresponding to Latin dorsualis, "of the back" from dorsum, "back", dors, "back of the body" + -al, "pertaining to, referring to".
It contains organs of the nervous system that coordinate body functions and is divided into two parts: the cranial cavity and the spinal cavity; both of which are defined in this unit.