Sagittal Plane Definition
The sagittal plane is an anatomical boundary that exists between the left and right sides of the body. The sagittal planes runs parallel to the longitudinal axis of the organism, or from the mouth to the tail. The direction toward the sagittal plane is called medial, while the direction away from the sagittal plane is known as lateral. The sagittal plane is similar to the coronal or frontal plane, which also runs with the longitudinal axis. The transverse plane crosses the sagittal plane perpendicularly, and divides the organism into dorsal and ventral parts. A section that runs parallel to the sagittal plane is called a parasagittal plane. The sagittal plane can be seen in relation to the other planes in the following image.
Human anatomy has a slightly different orientation. This is not due to any difference in human anatomy, but simply the fact that humans tend to orient themselves vertically, while other animals orient themselves horizontally. The sagittal plane still divides humans into left an right halves, but runs vertically instead of horizontally as seen in the following image.