(anatomy) A plane traversing the direction from top to bottom, resulting in the formation of left and right portions
A sagittal plane is used in anatomy to refer to a plane that is traversing the direction from top to bottom, and therefore, forms left and right sections especially in the body of a bilaterally symmetrical animal.
Related terms are mid-sagittal plane and parasagittal plane. The mid-sagittal plane is a plane passing vertically through the midline, subsequently dividing the body into left and right halves of equal proportion particularly in a body exhibiting bilateral symmetry. In human body, a midsagittal plane is one that is passing through the midline structures such as the navel and spine. Together with umbilical plane, the mid-sagittal plane forms the four quadrants of the human abdomen.1
The parasagittal plane is the term used to refer to a plane situated alongside or parallel to the sagittal plane, but not including the median plane passing through the midline. An example is the midclavicular line crossing through the clavicle.
1 Kapit, W. (2014). The anatomy coloring book. San Francisco: Pearson.