Final answer:
The body is divided into equal halves by the midsagittal plane, also called the median plane, which creates symmetrical right and left sides.
Step-by-step explanation:
When the body is divided straight down the middle into equal halves, it is called the midsagittal plane or median plane. This plane runs vertically through the body, creating symmetrical right and left halves. Apart from the midsagittal plane, there are other anatomical planes such as the frontal plane (coronal plane) which divides the body into anterior and posterior sections, and the transverse plane which cuts the body horizontally into upper and lower portions.