The inferior gemellus is a small muscle deep in your butt/hip area, underneath the bigger glute muscles. It sits very close to the hip joint and works as part of a tight team of deep hip muscles that help control how your thigh bone rotates in the hip socket. Think of it as a precision stabilizer rather than a big power producer.
It starts from a bony point on the pelvis called the ischial tuberosity, which is the same area you feel when you sit on a hard chair. From there it runs outward to attach near the top of the thigh bone at the greater trochanter, blending with the tendon of a neighboring muscle called the obturator internus. Because it attaches so close to the joint, it can make small but important adjustments to hip position.
Its main job is to externally rotate the hip, meaning it helps turn your thigh and knee outward. It also helps stabilize the hip when you’re standing on one leg, walking, running, changing direction, or squatting. When your pelvis and ribs are stacked well and your hip stays centered, you transfer force better through your trunk, which matters when you’re training hard for a lean look and tight midsection.
If the inferior gemellus or its neighboring deep hip rotators are weak, overworked, or irritated, you might notice deep butt pain, hip tightness, or a pinchy feeling with certain ranges, especially if you sit a lot or repeatedly train heavy lower body with limited mobility. Strengthening it directly isn’t usually necessary, but it benefits from good hip rotation control and stable glutes through full range movements, plus smart warm-ups and progressive loading.