To better identify the locations of the organs that contribute to vital functions, you need some points of reference for description. To serve that function, we will now define different planes of the body. These imaginary flat surfaces run through the body in different directions. They are used by medical professionals to examine various internal body parts. Directional orientation is another anatomical tool used to describe how parts of the body are related to one another.

Each organ system spans large regions of the human body. It is helpful, therefore, to establish reference planes and directions that can help us describe specific locations of structures as we discuss them. To make sure everyone is talking about the same thing, anatomists and physiologists often refer to anatomical position and the body planes that penetrate it. Anatomical position describes a person standing upright, with the arms at the sides and the palms facing forward (as demonstrated in the image below). Body planes (a plane is a flat, two-dimensional surface) are imaginary surfaces that run through the body and divide it into different sections. We can talk about a specific location using the planes as reference points within the anatomical position.

Figure 1. Sagittal, Coronal, and Transverse body planes and their intersections. By YassineMrabet (Human Anatomy Planes)/Wikimedia Commons/CC-BY-SA.

There are an infinite number of planes running through the human body in all directions. However, we will focus on the three planes that are traditionally used when discussing human anatomy (see Figure 1). First is the transverse plane, (also called the horizontal plane), which divides the body into top and bottom. In anatomical position, transverse planes are parallel to the ground. The second is the coronal plane, which is a vertical plane that divides the body into the front and back sections. If you do a “belly flop” into the water, you sink into the water via the coronal planes. Finally, we will refer to the sagittal plane, which divides the body into left and right sections with a vertical plane that passes from the front to the rear.

You can use other terms to further pinpoint an anatomical location. These terms are used to describe a location in relation to other structures. Some of them may be terms you have heard in everyday conversation; a lateral pass in football, for example, is a pass toward the sideline.

Proximal, Distal, Superficial, Deep

These next terms are used when referring to either appendicular parts of the body (arms and legs) or position in body relative to the external surface. These are proximal, distal, superficial, and deep.

Directions and Orientation

Table 1 lists all of the human anatomical directions that we discussed.