LEARNING OBJECTIVE: Identify anatomical terms of position and direction.

The planes of the body are imaginary lines dividing it into sections. These planes are used as reference points in locating anatomical structures. As shown in figure 1-1, the median, or midsagittal, plane divides the body into right and left halves on its vertical axis. This plane passes through the sagittal suture of the cranium; therefore, any plane parallel to it is called a sagittal plane. Frontal planes are drawn perpendicular to the sagittal lines and divide the body into anterior (front) and posterior (rear) sections. Since this line passes through the coronal suture of the cranium, frontal planes are also called coronal planes. The horizontal, or transverse, plane, which is drawn at right angles to both sagittal and frontal planes, divides the body into superior (upper) and inferior (lower) sections.

Figure 1-1.—Planes of the body.

To aid in understanding the location of anatomical structures, you should use a standard body position called the anatomical position as a point of reference. This anatomical position is assumed when the body stands erect with the arms hanging at the sides and the palms of the hands turned forward (fig. 1-2).

Figure 1-2.—Anatomical position.

Other commonly used anatomical terms include the following: