The area commonly referred to as the “side of the butt” is anatomically known as the lateral gluteal region, a complex junction of muscle, bone, and connective tissue in the posterior hip and upper thigh. This article clarifies the specific anatomical structures that define this region, explaining its significance for body contour and functional movement beyond the familiar Gluteus Maximus.
The Anatomical Name for the Side of the Butt
The lateral hip region is primarily defined by the Gluteus Medius and the Gluteus Minimus. These two muscles are positioned on the outer surface of the pelvis, lying beneath the larger Gluteus Maximus, which forms the bulk of the rear buttocks. The Gluteus Medius is a broad, fan-shaped muscle that sits over the Gluteus Minimus, the smallest and deepest of the three main gluteal muscles. The Medius and Minimus are responsible for the distinct shape and contour of the upper, outer hip. Both muscles originate on the ilium, the flared bone of the pelvis, and converge into tendons that attach to the top of the femur (thigh bone) at a bony landmark called the greater trochanter.
How the Hip Bone Influences Shape
The underlying skeletal structure, particularly the pelvis and the femur, dictates the contour of the side gluteal area. The greater trochanter, a large, palpable bony prominence on the upper, outer part of the thigh bone, acts as the attachment site for the Gluteus Medius and Minimus muscles, influencing the lateral width of the hip. The position and size of the greater trochanter vary between individuals, contributing to differences in hip shape. For example, the distance between the top of the pelvis and the greater trochanter affects how overlying muscles and fat deposits appear. Variations in the angle of the thigh bone relative to the pelvis can also create an indentation, sometimes called “hip dips,” which is a structural characteristic determined by bone shape.
Why These Muscles Are Crucial for Walking
The Gluteus Medius and Minimus are collectively known as the hip abductors. Their primary biomechanical function is to stabilize the pelvis during single-leg support activities, such as standing, running, or walking. When a person lifts one foot off the ground, the Gluteus Medius and Minimus on the stance leg contract powerfully, preventing the pelvis from dropping down on the side of the lifted leg. This ensures the torso remains upright and balanced over the supporting limb, which is a fundamental part of the human gait cycle, allowing for smooth, efficient movement. Weakness in these muscles can lead to instability and compensatory movements, where the pelvis visibly shifts or drops with each step, creating a chain reaction of poor movement patterns throughout the lower back, hips, and knees.