Neural Coordinate Systems

Part Of: [Neuroanatomy] sequence

Sagittal, Transverse, and Frontal

An efficient way to navigate three-dimensional spaces is to use three orthogonal axes.

  • Pilots use roll, pitch, and yaw.
  • Geometricians use x, y, z.
  • Anatomists use sagittal, transverse, and frontal.

Brain Geometry- Three Planes

We also need a language to navigate anatomical space.

  • Lateral/Medial means side/center (adjusting X, moving the sagittal plate left & right)
  • Superior/Inferior means top/bottom (adjusting Y, moving the transverse plate up & down)
  • Anterior/Posterior means belly/back (adjusting Z, moving the frontal plate forwards & backwards)

Notice how directions along the X axis (first bullet) are of a different style than other axes. While the other directions gesture at an infinite scale (-∞, +∞), the first gestures at [0, +∞).

This simplification is only possible because of symmetry: nearly all vertebrates exhibit bilateral symmetry along the sagittal axis.

Neuraxis Distortions

Anatomy maintains a lot of duplicate names (synonyms). Anatomy coordinate systems are no exception:

  • Ventral/Dorsal is synonymous with front/back (Anterior/Posterior)
  • Rostral/Caudal is synonymous with top/bottom (Superior/Inferior)

To be perfectly frank, anatomy naming conventions seem inefficient to me. I wonder if too much has been sacrified in pursuit of historical contiguity. But sometimes, “redundant” synonyms come in handy. Consider the following example:

Humans are bipedal. It turns out that this evolutionary innovation deforms the neuraxis.

Brain Geometry- Deformed Neuraxis

 

Because of the bend in the human neuraxis, “front & back” is in danger of being confused with “top & bottom”.

Fortunately, we can use the above synonyms to disambiguate direction in the brain.

  • In the brain alone, Ventral/Dorsal becomes synonymous with bottom/top (Inferior/Superior)
  • In the brain alone, Rostral/Caudal becomes synonymous with front/back (Anterior/Posterior)

Brain Geometry- Adjusted Synonyms

 

Perhaps humans should just give up this walking upright business altogether. It would make anatomy much easier!

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3 thoughts on “Neural Coordinate Systems

  1. Kevin,
    The anatomical plane graphic is a perfect fit for some documentation I’m generating. Did you create it or is it derived from another source? I would appreciate your permission to snag it. Thanks.

    PS: I like what you’re doing on this blog. Keep it up. We have some commonalities – I graduated from the UW with a Computer Engineering degree (2001) and currently work at an eastside medical device startup targeting neurological applications.

    Like

    1. Hi Travis,

      I personally have no reservations with you snagging any of the three graphics here. The first two were inspired by other sources, the third entirely from scratch.

      Glad you like my work! I am now following your blog too. 🙂 It looks like your intellectual trajectory is somewhat similar to mine: I also used to be more involved with religion than I am now.

      Keep in touch! I suspect our interests/writings will overlap the most on theories of consciousness and of the cognitive construction of moral feeling.

      Like

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