Only gluteus maximus can be injected. Draw a line from the top of gluteal fissure to the top of iliac crest, divide the buttocks into four quadrants, choose the outermost quadrant as the injection area, and avoid the internal angle. There is another method. At the outer upper third of the connecting line between the anterior superior iliac spine and coccyx, the simplest way is to make a fist, but the middle finger is half extended, the thumb is buckled at the middle fingertip, and the first joint protruding from the middle finger is placed on the iliac spine. The palm root is where the needle is inserted. Thin man is probably the place where the ass is sunken. Better go to the hospital. Do not go beyond the middle of the bottom. You can only hit the outside half. If you accidentally prick the sciatic nerve, you will be paralyzed.