If the iliacus could speak, I think it would say something like this:
“Why does the psoas major get all the attention?
Really, did I do something wrong? Because last time I checked, I’m a muscle too. Sure, I may not have as many attachments as the psoas and yeah, I only connect the pelvis to the lesser trochanter. But did you check out the size of my attachment on the ilium? That’s substantial.
Don’t know what happened, but first we were inseparable. Anatomists lumped us together and actually referred to us as the iliopsoas (some still do) because we share a tendon that attaches to the femur. And then we got separated and now the psoas gets all the attention. All I hear about is psoas, psoas, psoas.
Pain in your hip? must be the psoas! One leg is longer than the other? Must be the psoas! Lateral bend in the spine? Must be the psoas! I mean look at me, I am a sizable muscle that packs a lot of power! And I have one function which makes me stronger (muscles with more than one function and multiple attachments tend to be weaker). I can’t get no respect!”
That’s what I think the iliacus would say. And for some reason I think it would say it with a Jersey accent.
I rarely paid much attention to the iliacus. I read so much about the psoas (there are a bunch of books and articles written about it) and while I still think that the psoas is an important muscle to know, the iliacus deserves attention too. Just to reiterate – muscles with more than one function at more than one joint (like the psoas) have to distribute their force across different lines of pull and therefore tend to be weaker than muscles with one function. The iliacus has a large and powerful attachment on the inside of the ilium. That gives it a lot of leverage to do its one job – which is to flex the thigh at the hip joint or anteriorly tilt the pelvis if the thigh is fixed.
I thought I was all smart with my anatomy knowledge. I walked into my appointment with my orthopedic massage therapist thinking that the tightness I was feeling along parts of the left side of my body were due in large part to a tight psoas on that side. I talked the talk with my OMT and when it came time for him to assess me I said – “you think it’s my psoas, right?”
“Nope!” he said. “Your psoas isn’t really working on that side. It’s weak and it is being inhibited by your iliacus. Your iliacus is the culprit. That is what is tight.”
We did a test which illustrated the huge difference from my right psoas to my left. I was shocked. And ever since then I have been paying a lot of attention to my iliacus. So here is the skinny:
The iliacus attaches on the internal ilium and the lesser trochanter of the femur. It is a powerful muscle that flexes the thigh at the hip joint (the iliopsoas combined is the most powerful hip flexor). It also laterally rotates the thigh at the hip joint but this is a weak action for this muscle. Its primary role is flexing the hip.
Tune back in on Friday for some tips to stretch and strengthen the iliacus!