There is the corticospinal system, which begins at the top of the human brain — essentially, at the crown of the tree.
This corticospinal system gradually descends downward and transitions into the roots. Along the way, part of this system becomes the upper motor neuron, while in the roots it is predominantly represented by lower motor neurons and motor reflex arcs.
Why does it look like this? 🤔
Because the human body is, in fact, a structure containing a vast number of highly diverse muscles. These muscles can be activated in countless combinations. The crown of the tree — the human brain — is capable of iterating through these combinations and achieving specific postures.
The trunk of the tree mainly represents motor neurons that transmit information along the spinal cord, partially including the corticospinal tract, which forms systems of complex reflexes. The roots, in turn, represent the lower motor neurons.
