The study of the human body requires a standardized frame of reference to accurately describe the location of organs, injuries, and procedures. This shared terminology begins by assuming the body is in the standard anatomical position: standing upright with the feet shoulder-width apart, the head facing forward, and the arms hanging at the sides with the palms turned to face forward. Body planes are imaginary flat surfaces used to conceptually slice the body into sections, providing a precise, three-dimensional map for anatomical reference. These planes ensure that descriptions of the body remain consistent and universally understood.
Why Anatomical Planes are Necessary
Anatomical planes provide a universal language that eliminates the ambiguity often found in common directional descriptions. Without this standardization, a physician describing a structure as “above” or “in front of” another could be misinterpreted depending on the patient’s posture. By using a fixed set of planes, medical professionals, researchers, and anatomists can communicate the exact location of a specific structure with precision. This system is useful when comparing findings across different patients or when documenting the progression of an illness or injury. This standardized frame of reference is foundational for both basic anatomical education and complex clinical practices, such as surgery and diagnostic imaging.
The Vertical Planes
The body’s structure is analyzed through two primary planes that run vertically, parallel to the long axis of the body. The first is the Sagittal plane, which is oriented from front to back and divides the body into left and right portions. This plane derives its name from the sagittal suture of the skull.
The Sagittal plane has an important distinction based on its position relative to the body’s midline. When the plane passes directly down the center of the body, dividing it into two equal left and right halves, it is called the Midsagittal or Median plane. Any other plane running parallel to the Midsagittal plane, separating the body into unequal left and right sections, is known as a Parasagittal plane. Both are used to describe structures that are either medial (closer to the midline) or lateral (farther away from the midline).
The second vertical plane is the Coronal plane, also called the Frontal plane. This plane runs from side to side, perpendicular to the Sagittal plane, separating the body into anterior (front) and posterior (back) sections. The Coronal plane is often used in medical imaging to evaluate the side-to-side symmetry and alignment of structures like the spine and major internal organs.
The Horizontal Plane
The third standard plane, known as the Transverse plane, runs horizontally, parallel to the ground when the body is in the anatomical position. This plane is also referred to as the Axial or Horizontal plane. The Transverse plane divides the body into superior (upper) and inferior (lower) portions.
Because the Transverse plane cuts the body into cross-sections, it is valuable in modern diagnostic medicine. Imaging technologies like Computed Tomography (CT) scans and Magnetic Resonance Imaging (MRI) most commonly utilize this plane to generate detailed views of internal anatomy. The resulting images, often called “slices,” allow clinicians to examine the layered arrangement of organs, tissues, and vessels at a specific horizontal level.
A Transverse plane image of the abdomen can clearly reveal the spatial relationship between the liver, stomach, and spleen, aiding in the identification of lesions or masses. This cross-sectional visualization is superior for assessing the depth and extent of abnormalities within complex regions like the brain or spinal cord.