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Variation in the Anatomy of a Piriformis Muscle

There can be a lot of variation in the anatomy of the piriformis muscle and how it’s sort of it’s relationship to the nerve structures as well. Sometimes you get one single piriformis muscle. Sometimes you get essentially two piriformis muscles and kind of everything in between. Even with MRI imaging, sometimes that isn’t clear beforehand, but you just have to kind of be careful as you’re going in here and always be expecting the unexpected, so to speak.

This is a very interesting configuration, it’s sort of the typical split piriformis where the lateral division of the sciatic nerve is running between the two muscle bellies, but then there’s another contribution coming from probably S2 that is coming through the muscle in a different location, and then coming down and joining with the rest of the nerve. Definitely going to take a video of this. Cases sometimes are kind of like, let me have some irrigation, unraveling the pieces of a puzzle. It’s like, how is everything fitting together? How can you dissect it so that you’re not injuring the nerves or the vessels, but still get access to the muscle and remove it safely.