Directions and Planes of Section

There are a number of special words that are used to describe the position and direction of brain structures. These words help describe the location of structures relative to other structures. For example, we can say that the frontal lobe is "rostral" to the occipital lobe.

The brain, like all biological structures, is three dimensional. So, any point on or inside the brain can be localized on three "axes" or "planes" - the x, y and z axes or planes. The brain is often cut ("sectioned") into pieces for further study. These slices are usually made in one of three planes: the coronal plane, the horizontal plane or the sagittal plane.

The coronal plane, horizontal plane and sagittal plane are shown in the figure on the right. The coronal plane is also called the frontal plane. Slices of the brain taken in the coronal plane are similar to the slices from a loaf of bread. Horizontal cuts are made as if you were slicing a hamburger bun or bagel.

The sagittal plane divides the right and left side of the brain into parts. The midsagittal plane would divide the right and left sides of the brain into two equal parts, like cutting down the middle of a baked potato before you put on the toppings.

The figures below show the human brain in the three planes of section on "synthetic MR" images produced by BrainWeb:

Coronal Section
Sagittal Section
Horizontal Section

You can find some photographs of coronal sections from the human brain at the Comparative Mammalian Brain Collection.
While visiting a new city or country, people often bring along a map. Neuroscientists who study the brain also use maps to identify exactly what part of the brain they are examining. These maps of the brain are called stereotaxic atlases. Just like maps, stereotaxic atlases use words to describe direction. However, instead of "north", "south", "east" and "west", the following words are used to describe direction in the brain (and other parts of the body too):

Directional Terms of the Body

Direction Description
Side View
Front View

Ventral Toward the belly (front)

Dorsal Toward the back

Rostral Toward the nose

Caudal Toward the tail

Superior Toward the top of the head/body

Lateral Away from the middle

Medial Toward the middle

Bilateral On both sides

Ipsilateral On the same side

Contralateral On the opposite side

Try it!	Do you like interactive word search puzzles? Make sure your browser is "java-enabled" and try this one: Directions and Planes of Section Puzzle
	The Washington University School of Medicine also discusses planes of section and has some excellent human brain coronal section images.

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