Gluteal sulcus
（重定向自Gluteal fold）
The gluteal sulcus (also known as the gluteal fold, fold of the buttock or horizontal gluteal crease) is an area of the body of humans and great apes, described by a horizontal crease formed by the inferior aspect of the buttocks and the posterior upper thigh. The gluteal sulcus is formed by the posterior horizontal skin crease of the hip joint and overlying fat, and is not formed by the lower border of the gluteus maximus muscle, which crosses the fold obliquely. It is one of the major defining features of the buttocks. Children with developmental dysplasia of the hips are born with uneven gluteal folds and can be diagnosed with physical examination and sonogram.