The sacroiliac joints reside among the sacrum (the tailbone phase of your spinal column) along with the prominent wing-like iliac bones that variety the pelvic girdle. There are 2 SI joints, a single around the still left and 1 on the ideal (highlighted in pink in the image higher than), https://www.theorthopaedicandpainpractice.com/service/hip-groin-pain/