Lemon, R. N. Descending pathways in motor control. Annu. Rev. Neurosci. 31, 195–218 (2008).

This is a relatively old paper, and there have likely been developments in our understanding in the last 13 years since it came out. Nevertheless, this was a beautifully written summary of the descending pathways in motor control. For someone with a poor understanding of the brain's anatomical and functional organization, this was a worthy read.

The paper is organized as an attempt to answer five relevant questions to summarize our current understanding of the descending pathways in motor control.

The author takes a comparative-biology approach to delineate the role of descending pathways in the control of skilled hand movements. The paper provides some answers to the following questions:

1. How are the descending pathways organized and what are their characteristic features?
2. Do the descending pathways have specific functions or are they multifunctional?
3. Is the corticospinal track a motor pathway?
4. Is the organization of these descending pathways conserved across species?
5. What is the functional significance of direct cortical connections to target motor neurons?

How are the descending pathways organized and what are their characteristic features?

The paper starts this section by listing ten characteristic features of descending pathways, which are:

1. Origin: Where does the pathway originate from?
2. Synaptic input: What inputs does the pathway receive?
3. Fiber number and size: The distribution of the fiber sizes and numbers.
4. Course: What path does the fiber follow?
5. Target/termination: Where does the pathway terminate (interneurons, motor neurons, etc.)?
6. Collaterals: What other supraspinal targets does the pathway innervate?
7. Molecular identity: What molecules are employed for axonal guidance, target finding, synaptogenesis, etc.?