Final answer:
The gluteal fold marks the lower margin of the buttocks and the upper margin of the back of the thigh. It is primarily formed by the gluteus maximus muscle.
Step-by-step explanation:
The gluteal fold demarcates the inferior boundary of the buttocks and the superior boundary of the posterior thigh. The gluteal fold serves as a demarcation line between these two regions of the human body anatomy. It is formed primarily by the gluteus maximus muscle, the largest and most superficial muscle in the gluteal area. When the gluteus maximus contracts, it helps to straighten the hip joint and extend the thigh backward, playing a crucial role in various physical activities like standing up from a sitting position, climbing, and running.
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