Where Exactly is Botox Injected in Order to Create a Browlift?

Thank you for your question. Shaping the brows is one my favorite parts of using Botox. It requires a very detailed understanding of the underlying anatomy as well as assessing each individual while they are animating their brows. By carefully placing Botox in the muscles that depress the brow, you can cause the brow to rest and relax in a lifted position. There are limits to how much you can lift, and for some surgery is better option. Incorrect assessment or placement can also lead to the reverse effect, so overall technique is critical. You can also shape the brow different. For example, you can raise the tail of the brow vs creating a raised arched brow vs creating a raised horizontal brow. It depends on the individual's desired brow aesthetic goals. I would consider this a very advanced technique so I would query your injector on their experience in this area.
As far as how many units may be needed, this also depends on which part of the brow you want to correct. For the inner brows, you may consider ~20 units (same as the frown line treatment). For the middle or outer brow, I generally use up to 5 units on each side.
You may also want to consider adding fillers to shape and raise the brow. Combining the two products can work synergistically together.

Thanks for your question.
 You can lift the tail of the eyebrow  by injection of Botox in the group of muscles that lower the eyebrow. When that muscle is temporary deactivated, it allows the eyebrow to lift and rest in a more youthful better position. It is one of my favorite part of Botx/Dysport treatment. 
Hope this was helpful.

Properly speaking, mere injection of Botox cannot give a patient a "brow lift".  A brow lift is a surgical procedure that transects the key ligaments that tether the soft tissues of the brow to the underlying bony architecture of the skull, then physically elevates the soft tissues of the brow to the ideal aesthetic level, then fixates the soft tissues of the brow in this new ideal position, so that the internal scar tissue formed by the healing of these tissues can maintain them in their proper position.  In our clinic, we perform brow lifts endoscopically, and fixate the elevated tissues with a bioabsorbable device called an endotine.Injection of Botox cannot do any of the things described above. The most that injection of Botox can achieve is a moderate, and temporary, elevation or reshaping of portions of the brow. It achieves this by weakening the vectors of pull of the muscles into which it is injected.  So, for instance, if one injects Botox into the segment of the orbicularis oculi muscle that exerts a downward pull on a portion of the brow, one can achieve a mild elevation or relaxation of that segment of the brow.  Alternatively, if one weakens the medial portions of the frontalis muscles with Botox, while leaving the lateral portions of the frontalis muscles untouched, one can generate a differential in the strength and direction of the upward traction of these broad muscles on the brow, and create different degrees of arching of the brow, or elevation of the tail of the brow.  It will generally take an entire week before the maximal effect of these Botox injections can be observed, and the aesthetic effect can last between three and six months, although generally closer to the shorter range of this spectrum.  While the effect of Botox utilized in this manner can be aesthetically useful, it in no way can compare to the power, artistic flexibility, and longevity of an endoscopic brow lift in elevating and shaping the brow.