Final answer:
The subcutaneous layer, or hypodermis, connects the skin to the underlying fascia and has a main function of fat storage, insulation, and cushioning.
Step-by-step explanation:
The main function of the subcutaneous layer, also known as the hypodermis or superficial fascia, is to connect the skin to the underlying fascia of the bones and muscles. It is composed of well-vascularized, loose, areolar connective tissue and adipose tissue. The adipose tissue in the subcutaneous layer serves as a mode of fat storage, providing insulation and cushioning for the skin.