In order to get the optimal lift of the inner corners or medial brows, Botox should be injected into the muscles that pull the brow down and together (inferiorly and medially). These depressor muscles are known as the corrugators and procerus muscles. When injected properly, these muscles cannot pull down and inwards, allowing the forehead muscle to lift and open the brows. If too much Botox is injected, and the frontalis or forehead muscle becomes affected and cannot lift or elevate the brow, one is left with a heavy or depressed medial brow. It is imperative that you see an experienced dermatologist, plastic surgeon or oculoplastic physician who understands this concept for optimal placement of Botox otherwise you will end up with an undesirable result. Hope this helps!