Video: Cardinal body planes and axes

Hey everyone! This is Nicole from Kenhub, and in this tutorial, we’ll be discussing the cardinal planes of the human body and the cardinal axes.

Before we begin discussing the specific cardinal body planes and axes, you may be asking yourself, what are they and why are they so important to the study of anatomy? Well, let me first begin by describing what we mean by the term “cardinal” in this respect. The term “cardinal” in and of itself means “of great importance or fundamental”. When we use it in anatomy in reference to the planes of the body or axes, we are basically saying that the cardinal planes or cardinal axes are the planes and axes that are of the greatest importance.

The other thing you need to know is that these planes and axes are described in reference to the anatomical position, which is the standard position of the body that is used to describe the position of body parts and positions of patients regardless of whether they are lying down, on their side or facing down.

In the anatomical position, the person is standing upright with the arms to the side, the palms facing forward with the thumbs pointing down away from the body and the feet placed slightly apart parallel to each other with the toes pointing forward. In this position, the head is facing forward and the eyes are looking straight ahead.

Now, let’s talk about what body planes and axes are.

First, the cardinal body planes are imaginary planes or flat surfaces that divide the body into sections. Although these planes can be drawn in any number of locations through the human body, three standard cardinal planes are designated as planes of reference, namely, the coronal plane, the sagittal, and the transverse plane.

As for the cardinal axes, these are straight imaginary lines that run through the body in three cardinal directions – the horizontal axis also known as the x-axis, the longitudinal axis also known as the y-axis, and the sagittal axis also known as the z-axis. When we talk about the cardinal axes of the body, we’re referring to a straight line around which an object rotates, such as the movement around the joint.

So why do we use these cardinal body planes and axes? Well, these terms are part of the universally accepted language of anatomy that is used to describe structures according to their position in the human body. The use of these terms helps to avoid confusion and allows for precise communication between anatomists and health professionals.

So now that you know what these planes and axes are and have an understanding as to why they are used in anatomy, let’s look at them individually in a bit more detail.

First, let’s talk about the cardinal planes.

The coronal plane is a vertical plane that divides the body into an anterior or front part and the posterior or back part. These plane runs parallel to the coronal suture of the skull, hence, its name. The image you see on the right demonstrates the mid-coronal plane, which divides the body into equal anterior and posterior halves.

Another vertical plane is the sagittal plane. This plane, however, divides the body into a left and right part. It is given its names because it runs parallel to the sagittal suture of the skull. This image in particular shows the midsagittal plane, which passes through the body from front to back at the midline essentially dividing the body into equal left and right halves.

The third cardinal body plane – the transverse plane – is a horizontal plane that runs parallel to the ground. This plane divides the body into a superior and inferior part. In anatomy, sections taken in the transverse plane of an organ or tissue are also referred to as cross-sections.

Now, let’s talk about the cardinal axes. As I mentioned earlier, we refer to these axes most often when we talk about the movement of a joint and we will see some examples of such movements as we describe these axes.

Starting with the horizontal axis, also known as the x-axis, you can see that this axis is a straight line that runs from left to right. This axis lies at the intersection of the coronal and transverse planes. Hinge joints such as the elbow joint perform movement along this axis – flexion and extension to be more specific.

The longitudinal axis, also known as the y-axis, is a line that runs through the body from top to bottom and is perpendicular to the ground as seen here on this image. This axis lies at the intersection of the coronal and sagittal planes. A pivot joint such as the atlanto-axial joint can perform movement around this axis, specifically, medial and lateral rotation.

Finally, the third cardinal axis is the sagittal axis, also known as the z-axis. This axis runs anteroposteriorly from the front of the body to the back of the body and lies at the intersection of the sagittal and transverse planes. The carpometacarpal joint of the thumb, which is a saddle joint, performs movement around the z-axis, specifically abduction and adduction of the thumb.