Final answer:
The hypodermis, also known as the subcutaneous layer, is a connective tissue layer below the dermis. It is not considered part of the skin, but it provides insulation, cushioning, and fat storage for the integumentary system.
Step-by-step explanation:
The hypodermis (also called the subcutaneous layer or superficial fascia) is a layer directly below the dermis and serves to connect the skin to the underlying fascia of the bones and muscles. It is not strictly a part of the skin, although the border between the hypodermis and dermis can be difficult to distinguish. The hypodermis consists of well-vascularized, loose, areolar connective tissue and adipose tissue, which functions as a mode of fat storage and provides insulation and cushioning for the integument.