How and where do nerves share pathways to the brain?
The first layer of sensory integration from neural interconnection lies in the spinal dorsal horns (for somatosensory stimuli), and the spinal anterolateral system (for painful stimuli). It resembles option #2 much more than option #1.

Addenda: Since you are asking a lot about neuroanatomy and neurophysiology, I suggest those 2 beginner books:


Neuroanatomy Text and Atlas, John Martin
Neuroscience, Dale Purves