It consists of 3 important parts: 2.1 Infundibulum is the upper part from the opening of the sebaceous gland to the area where the hair is inserted into the skin. 2.2 Isthmus from the opening of the sebaceous glands to the area where the muscles come to the island. This is the part where the muscles that control the occurrence of goosebumps are located. This part is very important because there are stem cells in the bulge that can regenerate hair. 2.3 Inferior segment, the bottom of the hair. Since the area where the muscles come down is visible as a bag. This section contains blood vessels, nerves, and pigment-producing cells that give hair its different colors.