Hi,
I agree with both points above. It's very important to keep the head/back/arse inline (*Waits for Dibble input on that comment!) this stops you twisting and putting too much weigh on the inside handlebar which will effect the bike's stablity in the corner.
Also, to bend your inside arm will as phil_h states allow your body to move to the inside of the bike and the corner. This the idea as it reduces the effect of the cornering forces on you and the bike, it's also a shorter distance to fall.
All the best
Andy