The oblique muscles are often thought of as the waist muscles. They contribute to pain on your side in the rib cage and waist area, lower abdomen, groin, and pelvis. They can also contribute to heartburn, indigestion, bladder pain and incontinence, and testicle pain.
The serratus posterior inferior muscle contributes to pain in the lower back between the bottom of the ribs and the top of the hip. Pain is increased when you twist the torso, bend over, and stretch to reach overhead.
The rectus abdominis contributes to pain in the area around the sternum, across the upper back, across the buttocks, the lower abdomen, the pelvis. and testicles. It can also contribute to heartburn, indigestion, feeling bloated as well as mimicking urinary tract infection pain.