The human body is (generally) bilaterally symmetrical – that is the midline forms an axis where the right and left side are approximate mirror images. However, there are other ways of visualising and describing structures and locations in the body. This is probably most well known in viewing a medical image where different planes and sections are used and knowing which plane or section is used, allows interpretation of the image. There are five key planes (Figure 1.9) used in anatomy and physiology, which are used by medical professionals to refer to different sections (flat surfaces) and views.

Sectional Planes

Frontal Plane

The frontal plane, also known as the coronal plane, is used to separate the body into the anterior and posterior portions. This is a vertical plane running from the left to the right side of the body or a structure to make two distinct sections. An example is shown in Figure 1.10.

Sagittal Plane

The sagittal plane is another vertical divider which separates the body into right and left sides, similarly to the midline. When the sagittal plane runs exactly along the midline, the view is referred to as the midsagittal plane creating two equal mirror images of the right and left side of the body (Figure 1.10). When the sagittal plane lies adjacent to the midsagittal plane, creating two unequal right and left side views, it is referred to as the parasagittal plane.

Transverse Plane

The transverse plane is a horizontal divider which separates the body into top and bottom sides (Figure 1.10). This is sometimes referred to as the axial, or horizontal, plane. It runs perpendicularly to the frontal (coronal) plane or the sagittal plane. It separates the view into superior and inferior divisions.

Oblique Plane

Oblique, by definition, refers to an angle (or a line) that lies neither horizontally nor vertically. Rather, oblique refers to a plane that is at an angle other than 90°, or slanting (Figure 1.10). There is no defined angular degree which oblique planes follow, however it is commonly displayed at a 45° angle to differentiate it from the frontal and transverse planes.