Anatomists and medical professionals rely on a common language to accurately describe the location and movement of body structures. Because the body is three-dimensional, the study of human anatomy utilizes imaginary flat surfaces called anatomical planes. These planes are used to “slice” the body or an organ into specific sections for precise description. This standardized, two-dimensional reference system ensures that anatomical descriptions are understood universally.
Establishing the Reference Point: Anatomical Position
Describing the body’s organization requires a fixed starting point, as the location of any structure changes with movement. This standard baseline is known as the anatomical position. The body is always described as if the person is standing upright with the head facing directly forward. The feet are positioned slightly apart and pointing forward, and the arms are hanging at the sides with the palms turned to face forward. All subsequent descriptions of body structure and movement are referenced from this single orientation.
The Sagittal Plane: Dividing Left and Right
The sagittal plane is a vertical plane that runs from the front of the body to the back. This division produces left and right portions of the body or organ being examined. Movements like bending forward or backward are often described in relation to the sagittal axis. The sagittal plane is used extensively to visualize structures running along the length of the body, such as the spinal cord or the long axis of a limb.
Midsagittal and Parasagittal Planes
A special type of sagittal cut is the midsagittal plane, sometimes called the median plane. This specific plane passes directly through the midline of the body, dividing it into two perfectly equal left and right halves. When a vertical cut runs parallel to the midsagittal plane but does not pass through the exact center, it is called a parasagittal plane. These parallel planes divide the body into unequal left and right portions, allowing for examination of structures without obstruction from the midline.
The Coronal (Frontal) Plane: Dividing Front and Back
The coronal plane, also known as the frontal plane, is a vertical plane that divides the body into anterior (front) and posterior (back) sections. This plane is oriented perpendicular to the sagittal plane. A cut made along the coronal plane separates the front of the body from the back, with the front portion referred to as the anterior or ventral section, and the back portion as the posterior or dorsal section.
This plane is useful in medical imaging for visualizing the relationship between surface structures and those situated deeper within the body cavity. Movements like side-to-side bending of the trunk or abduction and adduction of the limbs occur within the coronal plane.
The Transverse (Horizontal) Plane: Dividing Top and Bottom
The transverse plane, sometimes called the horizontal or axial plane, is the only non-vertical plane. It runs parallel to the ground and divides the body into superior (upper) and inferior (lower) portions. This plane is perpendicular to both the sagittal and coronal planes, establishing a three-dimensional grid system for spatial referencing.
A transverse cut separates the upper part of the body from the lower part. This plane is the standard for viewing cross-sectional images produced by technologies like Computed Tomography (CT) scans and Magnetic Resonance Imaging (MRI). Transverse views reveal internal details and are frequently used to assess the width, depth, and composition of structures like the abdomen or the brain.