Preliminaries: Axes and Planes in the Brain

Neuroscience papers refer to several different features about the brain.  Sometimes, they refer to a specific fold, broad area, or certain type of direction.  A general knowledge of the following terms and areas will be the first step to reading and understanding neuroscience literature.   Here we will deal with the axes and planes in the brain.

Scientists refer to directional locations in the brain with reference to it’s 3D axes.  I wish these axes were just x, y, and z, and we could all understand them without needing special terminology, but alas, we need to put in SOME work.  This is because x, y, and z describe spatial coordinates, and when a brain’s orientation in space changes, the x, y, and z axes will cross the brain through different points than they previously did.  The following axes and planes are defined within the body, and changing orientation will not alter the way they cross the brain.  So, imagine a real human head, facing out at you through the screen that you are reading this post on, and let’s get started!

Directions in the brain

The following are the axes in the brain and in parentheses, some of their alternate names.

  1. rostral-caudal (posterior – anterior):  This is the axis that is poking out of the screen towards you.  The caudal (posterior) direction is towards the back of the head, further away from the face.  The rostral (anterior) direction is closer to the face.  You may read terms such as “posterior parietal lobe”, and this would refer to the further back portions of the parietal lobe (I’ll get into the lobes in another post).  The rostral direction is sometimes called the cranial direction.  For illustration, imagine the head facing you turns to face up instead.  Now the rostral-caudal axis matches up with a different spatial axis than it did before.  This is why we need axes defined within the body.  Rotate the face back!
  2. dorsal-ventral (superior – inferior):  This is the axis that goes from the bottom (ventral, inferior) of the brain to the top (dorsal, superior). 
  3. left-right (lateral):  This one is pretty self-explanatory.  This axis goes horizontally across the brain.  Researchers can describe the left and right directions in the brain, and discuss how functional activity differs along them.  Please note that this is oriented from the head’s perspective.  So, if you are looking at someone face to face, their right hemisphere is on your left.

Planes in the brain

Just as there are planes containing two of the x, y, and z axes, there are planes in the brain, but containing two of the axes defined above.

  1. sagittal:  The planes that divide the brain into left and right parts.  They are perpendicular to the lateral axis.  The “midsagittal” plane is the specific sagittal plane that divides the brain into left and right hemispheres.
  2. coronal:  These are planes that are perpendicular to the rostral-caudal axis and divide the brain into anterior and posterior parts.
  3. transverse (horizontal, axial):  Lastly, these are planes are perpendicular to the dorsal-ventral axis and divide the brain into superior and inferior parts.

Now that you know the planes and directions in the brain, you are equipped to learn about the brain areas and their general functions.  This is because internal areas of the brain require a cross-section (slice) to view.

An image to bring it all together

axesplanes.gif
This is an image of the brain from the left side.  Taken from : http://homepage.smc.edu/russell_richard/Psych2/Graphics/human_brain_directions.htm

 

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