Directionsand Planes ofSection

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

The brain, like all biological structures, is three dimensional. So, anypoint 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.

Thecoronal plane (top) and thehorizontal plane (bottom) are shown in this figure on the right. Thecoronal plane is also called the frontal plane. Slices of the brain takenin the coronal plane are like the slices from a loaf of bread. Horizontalcuts are made as if your were slicing a hamburger bun or bagel.

The sagittal plane, which is not shown in the figure, divides the rightand left side of the brain into parts. The midsagittalplane would dividethe right and left sides of the brain into two equal parts...sort of likecutting down the middle of a baked potato before you put on thetoppings.

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 ofcoronal sections from the brain of an owl monkey from the Wisconsin Mammalian BrainCollection.
The rat brain and monkey brain are alsoavailable for viewing in coronal, horizontal and sagittal planes fromUCLA.
While visiting a new city or country, people often bring along a map. Neuroscientists who study the brain also use maps to identify exactly whatpart of the brain they are examining. These maps of the brain are calledstereotaxic atlases. Just like maps, stereotaxic atlases use words todescribe 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
SideView
FrontView
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

The Washington University School of Medicine also discusses planes of section andhas some excellent images of coronal sections of the human brain.

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