The vertebral axis is only one direction, and our bodies have two additional directions: front to back, and side to side. For animals that don’t carry their spine in an upright or vertical position, cranial and caudal will always denote the same directions. For the postcranial skeleton, we may also use cranial and caudal, which orient along the axis of the spine. These terms are always used when referring to directions on the head. The nostrils are most visible on the inferior aspect of the nose. For this reason, a long tradition in human anatomy uses these terms: Humans are special compared to many vertebrates in having a vertebral axis that runs roughly up and down, at least while we are standing up. For reasons like these, anthropologists use terms with specific anatomical meanings to talk about the Even left and right can cause confusion: sometimes we need to talk about the left surface of our right arm, for instance. For example, we could use higher and lower to refer to parts of our arms, but these terms will be confusing if we lift our arms over our heads. Other intuitive terms can fail us, however. Some of the terms are obvious, like right and left. It is important to note that all anatomical descriptions are based on the standard anatomical position unless otherwise stated.When talking about bones and teeth, we will need to use several terms to orient ourselves. This orientation represents the position of the skull if the subject were standing upright and looking straight ahead. In this position, the orbitales (eye sockets), lower margins of the orbits, and the poria (ear canal upper margins) all lie in the same horizontal plane. In humans, the standard anatomical position of the skull is called the Frankfurt plane. Standard anatomical position: The regions of the body in standard anatomical position, in which the body is erect. Dissection of cadavers was one of the primary ways humans learned about anatomy throughout history, which has tremendously influenced the ways by which anatomical knowledge has developed into the scientific field of today. The basis for the standard anatomical position in humans comes from the supine position used for examining human cadavers during autopsies. The positions of the limbs, particularly the arms, have important implications for directional terms in those appendages.

In addition, the arms are usually placed slightly apart from the body so that the hands do not touch the sides. In this position, a person is standing upright with the lower limbs together or slightly apart, feet flat on the floor and facing forward, upper limbs at the sides with the palms facing forward and thumbs pointing away from the body, and head and eyes directed straight ahead. The standard anatomical position is agreed upon by the international medical community. Medial indicates a feature is closer to this line, while lateral indicates features further from this line. Medial and lateral refer to position relative to the midline, which is a vertical line drawn through the center of the forehead, down through the belly button to the floor. Proximal refers to a feature that is closer to the torso, while distal refers to a feature that is closer to the fingers/toes. Proximal and distal describe relative position on the limbs. The front of the body is referred to as anterior or ventral, while the back is referred to as posterior or dorsal. Cranial refers to features closer to the head, while caudal refers to features closer to the feet. Relative location in the anatomical position: Many terms are used to describe relative location on the body. Thus, the standard anatomical position provides a “gold standard” when comparing the anatomy of different members of the same species. All descriptions refer to the organism in its standard anatomical position, even when the organism’s appendages are in another position. Standardization is necessary to avoid confusion since most organisms can take on many different positions that may change the relative placement of organs. Standard anatomical position is the body orientation used when describing an organism’s anatomy. When an organism is in its standard anatomical position, positional descriptive terms are used to indicate regions and features.

Anatomical position