Which plane of the body is perpendicular to its long axis and divides it into superior and inferior portions?

The transverse plane, also known as the horizontal plane, is defined as a plane that runs perpendicular to the long axis of the body. This plane divides the body into superior (upper) and inferior (lower) portions. In anatomical terms, when the body is in an upright position, the transverse plane slices through the body horizontally, allowing for views of the upper and lower structures separately.

This is particularly useful in various medical imaging techniques, as it provides a clear distinction between structures located above and below this plane, aiding in diagnostics and surgical planning. This differentiation is critical in understanding various body systems and how they relate spatially to one another within the human anatomy.