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Regional directional terms include anterior and posterior, dorsal and ventral, and lateral and medial. LEARNING OBJECTIVE [ edit ] Explain the need for standardized anatomical terms KEY POINTS [ edit ] In most vertebrate animals, the nose is referred to as the anterior end. The opposite to the anterior end, towards the tail, is the posterior end. The direction of the back of an animal is termed dorsal, while the direction of the belly is termed ventral. The directional term lateral is used as a modifier for both left and right, yielding the left lateral and right lateral sides. As an opposite to lateral, the term median is used to define a point in the center of the organism. TERMS [ edit ] ventral On the front side of the human body, or the corresponding surface of an animal, usually the lower surface. posterior Nearer the back end; nearer the caudal end of the body in quadrupeds or the dorsal end in bipeds. Give us feedback on this content: FULL TEXT [edit ] The Purpose of Anatomical Terminology Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation. They are universal terms that may be readily understood by zoologists who speak any language. While these terms are standardized within specific fields of biology, they can differ dramatically from one discipline to another. Differences in terminology remain a problem that, to some extent, still separates the fields of zoological anatomy (sometimes called zootomy) and Register for FREE to stop seeing ads human (medical) anatomy (sometimes called androtomy). The Need for Greater Standardization The Craniata (vertebrates) share a substantial heritage of common structure, allowing much of the same terminology to be used for all of them. It is necessary for this terminology to be based on the anatomy of the animal in a standard way to avoid ambiguities such as might occur if a word such as "top" were used, which might designate the head of a human but the left or right side of a flounder. Most animals, furthermore, are capable of moving relative to their environment. So while "up" might refer to the direction of a standing human's head, the same term ("up") might be used to refer to the direction of the belly of asupine human. It is also necessary to employ some specific anatomical knowledge in order to apply the terminology unambiguously. For example, while the ears would be superior to (above) the shoulders in a human, this fails when describing the armadillo, where the shoulders are above the ears. Thus, in veterinary terminology, the ears would be cranial to (i.e., "toward the head from") the shoulders in the armadillo, the dog, the kangaroo, or any other vertebrate, including the human. Likewise, 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. In veterinary terms, the belly would be ventral ("toward the abdomen") in all vertebrates. In human anatomy, as will be explained below, all naming is based on positions relative to the body in a standing (standard anatomical) position with arms at the side and palms facing forward (thumbs out). While the universal vertebrate terminology used in veterinary medicine would work in human medicine, the human terms are thought to be too well-established to change. The most obvious end-points are the "nose" and the "tail. " In terms of anatomy, the nose is referred to as the anterior end. The polar opposite to the anterior end is the posterior end. Another term for posterior is caudal, which is a term that strictly applies only to vertebrates, and therefore is less preferred, except in veterinary medicine where these terms are standard. The next most obvious end-points are the back and the belly. These are termed the dorsal end (Latin dorsum; back) and the ventral end, respectively. By connecting the outermost points, the dorsoventral axis is formed. This is commonly abbreviated to DV (or D-V) axis. The DV axis, by definition, is perpendicular (at right angles to) the AP axis at all times. The last axis, by geometric definition, must be at right angles to both the AP and the DV axes. The left side and right side of the organism are the outermost points between the two "sides" of the organism. When connected, these points form the left-right axis. It is important to note that the "left" and "right" sides are the sides of the organism, and not those of the observer. The directional term lateral is used as a modifier for both sides, yielding the left lateral and right lateral sides. As an opposite to lateral, the term median is used to define a point in the center of the organism. Different Directional AP Axes in Three Body Segments of a Horse Axis (A) (in red) shows the AP axis of the tail, (B) shows the AP axis of the neck, and (C) shows the AP axis of the head.