How do you interpret/draw out the simplified circuits in Sedra's Microelectronics?
It doesn't matter where the arrows go because they are separated from the circuit of interest by current sources.

For a more practical approach you may consider the arrows pointing up to a more positive supply while the arrows pointing down connect to a more negative supply. The important thing to realise is that 1 mA is coming from the top and I is departing to the bottom.