As a trainer, I get asked quite a bit about the anatomy of the forehead as it pertains to injections. Injectors want to lift the brows without dropping them. For more information about this topic you can see my post on the Botox Browlift: https://facialplasticsurgeryinstitute.com/2017/11/17/the-botox-browlift/
So how do the muscles of the brow play together? The larger muscle of the forehead, the Frontalis muscle is actually the only muscle responsible for lifting the brow. If this is injected, then there simply is nothing that can elevate the brow. The muscle starts at the top of the head in a layer between the skin and the bone (skull), known as the Galea (Or Galea Aponeurotica)
To know the layers of the scalp, we often use the acronym: SCALP. Skin, Connective tissue and fat, Galeal Aponeurotica, Loose Alveolar Tissue, Pericranium. The Frontalis muscle is continous with that Galeal Aponeurotica so sits above the loose connective tissue. This allows a smooth movement of the muscle. (We see this muscles very clearly when performing brow lifts in the operating room.)
So now that we know where the frontalis muscle inserts, we need to understand how the frontalis inserts to lift the skin of the brow and create expressions. The answer is simply that there are insertions to the skin at the level of the brow. These fingerlike insertions are spread across nearly the entire brow and travel from the deeper galeal layer up to the skin.
So let’s talk about the corrugator muscle. The corrugator muscle starts on the bone just underneath the middle brow along the rim of the eye socket. This muscle pulls the eyebrow down and inward. Where does it insert? Again (simply) in the skin at the level of the brow, typically around the midpoint of the brow.
So how does one inject the entire corrugator without injecting the frontalis muscle? Quite simply, you can’t! There are so many intermingling fibers that the two all meet in one point at the skin. So what are my tips for injecting as much corrugator as possible without much frontalis muscle? (Which I think is the better question since we are playing a tug of war with the brow and we simply want to weaken the corrugator MORE than the frontalis. There is no way to only weaken one.)
Tips for injecting the corrugators (and procerus) muscles:
- Look at the patient and see them move their muscles. By injecting into the body of the muscle you avoid a lot of the pitfalls of guessing where the muscle is and your injections will be more effective. See where the muscle belly is located, pinch it, then inject it.
- Use more botox or dysport at the origin of the muscle along the bone and less towards the tail of the corrugator. These are the injections towards the midline which are the origins of the muscle along the bone (So deeper injections at this point, usually 5-7mm deep).
- For your superficial injections along the tail of the corrugator, stay superficial and target right where the muscle is pulling maximally. Keep this injection slightly less than the other injections to minimize spread to the surrounding frontalis muscle. I perform this injection at a shallow angle to only catch superficial fibers and try to minimize my volume.
Okay, hope that helps some of you to conceptualize this relationship. I hope to add some real patient photos and ultrasound images in here to give you a better visualization soon! Happy injecting and let me know if you have any questions – firstname.lastname@example.org
Dr. Jordan Rihani is a national trainer and lecturer on injectable treatments and is considered one of the top injectors in Dallas Fort Worth. He performs injections in his clinics in Fort Worth and Southlake Texas. If you are interested in seeing Dr. Rihani for a treatment please give us a call to schedule.