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