Young Girl With A Nice Ass Buttocks

Anatomy
The buttocks are formed by the masses of the gluteal muscles or 'glutes' (the gluteus maximus muscle and the gluteus medius muscle) superimposed by a layer of fat. The superior aspect of the buttock ends at the iliac crest, and the lower aspect is outlined by the horizontal gluteal crease. The gluteus maximus has two insertion points: 1/3 superior portion of the linea aspera of the femur, and the superior portion of the iliotibial tractus. The masses of the gluteus maximus muscle are separated by an intermediate intergluteal cleft or "crack" in which the anus is situated.
The buttocks allow primates to sit upright without needing to rest their weight on their feet as four-legged animals do. Females of certain species of baboon have red buttocks that blush to attract males. In the case of humans, females tend to have proportionally wider and thicker buttocks due to higher subcutaneous fat and proportionally wider hips.