Bringing this up since there are core muscle and low back pain questions here time to time.
Many people are not aware of these two muscles - and the dysfunction they can lead to if chronically tight. Many youtube vids on how to release it.
https://www.painreliefvermont.com/iliacus-dysfunctionI just released my Iliacus last night after forgetting about
it for a year. An "ah ha!" moment.
After unsuccessfully trying to externally triggerpoint release my low back and hips last week.....I found the problem area was more internal along the inside of my left hip bone, which is lined with this hidden iliacus muscle.
Attachment points are inner hip to upper front/inner femur bone. The Psoas overlaps this but is a little higher and attaches to front side of lower vertabrea (cant access that part). .
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A summary of how to release iliacus muscle on the left side: (a couple you tube vids show this too):
1)On my back with left knee up (90 deg to floor), this relaxes the iliacus, psoas, abb muscles and your "guts".
2)Then "dig in" to inside of upper left hip bone crest with right fingers.
3)Carefully move stiff finger tips around till finding a touchy tight spot, then sustain pressure about
20 seconds several times.
The above is best done when you going to be least active, followed by rest- like in the evening before bed.
Laying on a ball 4" cannot get in there, and gravity we be in the opposite direction. Laying on a ball can release tight abbs though...another thing few people ever do...but should try.