I have brined successfully but never have been satisfied with the description of the physical processes involved.
Osmosis is the movement of the solvent(water) across the selective boundary from the region of low solute concentrate (salt) to the region of high concentration.
Applying this definition to brining, the brine should pull moisture from the meat rather than pull salt into the meat. Pour salt on a slug and watch it shrivel.
I am sure my confusion stems from applying high school chemistry concepts to a more complicated process. I would love to know where my understanding is breaking down.