What is the sinus tarsi? Well, that’s what we’re talking about today on the Doc On The Run Podcast.
I get lots of questions about sinus tarsi syndrome in runners and I figured it might be good to just explain what is the sinus tarsi. So, the sinus tarsi is a thing in your foot basically right here and a lot of times people that have sinus tarsi syndrome think they have ankle pain but it’s really weird because they’ll say well, it seems like it’s in my ankle, but it’s kind of on the top of my foot right here.
If you reach down in your ankle and find the lump of bone on the outside of your ankle, that is your fibula and then you push your finger forward you’ll find a little soft spot right on the side of your foot right to your ankle and when you stick your finger there, it feels like a soft spot, that’s the sinus tarsi.
Well, what does that mean? Okay, well, the word sinus means something, and tarsi means something. So, the tarsal bones are the bones in your foot. So, there’s two greater tarsal bones, that’s the heel bone and the talus and then you have a lesser tarsal bones which are the navicular cuboid and the three cuneiform bones in your midfoot. These are all the tarsal bones.
Tarsi refers to the tarsal bones. Sinus is basically a hole or a tract or a passageway, like you have most people when you say I have a sinus infection. It means the sinuses in your face, like behind your nose. Those are passageways where air moves through and gets circulated, cool, filtered, etc. You also have a sinus tarsi on your foot and that is not a thing that has air going through it, but it’s a space and if you look at it, you can actually see right through that space. And it’s basically a hole or a tunnel that goes between those bones. It’s kind of a conical shape and goes right through there. So that’s the sinus tarsi.
What’s in here that matters is you have several things. Number one is you have cartilage. So, where you have the joint in here, your subtalar joint, the talus sits on top of the heel bone, and it slides back and forth in the subtalar joint. So, you can get irritation of the cartilage in there.
There’s also a ligament that holds those two bones together called the interosseous talocalcaneal ligament, which sometimes can get sprained if you roll your ankle and get a subtalar joint sprain, in addition to an ankle sprain.
Then you have some nerves that are in there that can get aggravated and irritated. But most importantly, you have the synovial tissue that lines the inside of that joint. And if you roll your ankle or you twist it, you sprain it, you turn it in some weird direction or something or you really protonated a whole lot and banging the squishy synovial tissue between the bones, it can get inflamed. That’s when you get sinus tarsi syndrome.
Many of the people that have pain in that area, it’s really most of the time, it’s inflammation of that tissue inside there that’s getting squished and irritated and pushed on and if you can get that to calm down, it will generally leave you alone. So, very common, very easy to fix in most cases, but you have to understand what it is.
If you have one of those other things injured like you have some damage to the cartilage and you’re getting arthritis in there, that’s a different thing altogether. But hopefully this helps you understand a little bit more about the anatomy of the foot specifically the sinus tarsi.
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