It’s no surprise that the gluteus maximus is one of the most important muscles in the human body due to its vast attachments. Interestingly only around 20 percent of the gluteal fibres attach to bone. The remaining 80 percent attach to fascia (connective tissue).
For example, it connects to the humerus (the long bone in the upper arm) via the latissimus dorsi (lat) muscle through the thoracolumbar fascia, and it connects to the tibia (shin bone) via the iliotibial band, thereby influencing movement and transferring force throughout the entire body. What’s more, these attachment points allow for hip extension, hip abduction, and hip external rotation, all of which are expressed in the movements of daily life.
Reference: GLUTE LAB “The Glute Guy” Bret Contreras, PhD and Glen Cordoza.