Body planes in anatomy are imaginary flat surfaces used as reference points to divide the body into sections for anatomical study. These planes are essential for understanding the orientation, relationships, and spatial organization of anatomical structures.
The sagittal plane is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body resulting in equal division, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane or less commonly a longitudinal section.
The frontal plane is the plane that divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. ("Corona" is Latin for "crown.") "Coronal" usually refers to the skull sections.
The transverse plane is the horizontal plane that divides the body or organ horizontally into upper and lower portions. Transverse planes produce images referred to as cross sections. Oblique sections are cuts made diagonally between the horizontal and the vertical planes but are challenging to interpret.
Applications
Imaging techniques such as sonography, computed tomography, or MRI scan different images of a patient in a standard anatomical position and build an X-Y-Z axis around the patient to apply body planes to the obtained images. Individual organs can also get divided by planes to help identify minor internal details.
Body planes also describe anatomical movements through which a body travels. An anatomist could model a limb's range of motion by measuring which planes it can move through and how far it can travel.
Anatomical change during embryological development gets measured with body planes. For example, during human embryonic development, the coronal plane is horizontal but becomes vertical as the embryo develops into a fetus.
This text is partially adapted from Openstax, Anatomy and Physiology 2e, Section 1.6: Anatomical Terminology
