Botox binds at the connection point between the muscle and the nerves.. When this happens the nerves tell the muscle to move and the motor endplate of the nerves tells it to contract.  Botox binds to a specific protein at the motor endplate that send chemical messages (acetylcholine) which tells the muscle to move.  Botox stops this message getting through and with no chemical (acetylcholine) the muscle won’t move.  So although the binding process happens quickly, the final silencing of the chemical messenger can take longer, which is why it can take up to 2 weeks for the full effects of botox to be noticed.