In fields of anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species. While these terms are standardized within specific fields of biology, they can differ dramatically from one discipline to another.

The problem in consistency of naming occurs when ambiguous terms like "top" are used, which would be considered the head of a human, whereas for a flounder, the "top" would be the left or right side. In human anatomy, all naming is based on positions relative to the body in a standing (standard anatomical) position with arms at the side and palms facing forwards (thumbs out). In veterinary anatomy, many terms are given relative to the parts of the body, often in relation to the spine, which allows for consistency in terminology between vertebrate species that naturally assume a variety of positions. While the ears would be superior to (above) the shoulders in a human, this terminology fails when describing the armadillo, where the shoulders are above the ears. In veterinary terminology, the ears would be cranial to (towards the head) the shoulders in the armadillo, the dog, the kangaroo, or any other vertebrate. Similarly, while the belly is considered anterior to (in front of) the back in humans, this terminology fails for the flounder, the armadillo and the dog (although it could work for the kangaroo). In veterinary terms, the belly would be ventral to (towards the abdomen) in all vertebrates. While the universal vertebrate terminology used in veterinary medicine would work in human medicine, the human positional terms are too well established to change.

In invertebrates, locational terminology becomes more complicated, as many species are not bilaterally symmetrical. In these species, terminology depends on the type of symmetry present (if any).

Purpose

In the sciences dealing with the anatomy of animals, precise anatomical terms of location are necessary for a variety of reasons. General Definition: located on or affecting the same side of the body Two major problems arise with common usage, however. First, they tend to be language-specific, requiring translation into equivalent, or almost-equivalent, terms in other languages. They are not universal terms that may be readily understood by zoologists speaking other languages. Differences in terminology remain a problem that, to some extent, still separates the fields of zoological anatomy (sometimes called zootomy) and human (medical) anatomy (sometimes called androtomy).

The second, and larger, problem is caused by the very nature of animals. Most animals are capable of moving relative to their environment (see Fig. 1). So while "up" might refer to the top of someone's head when they are standing upright, the same term ("up") would describe their belly while they are lying down.