What is the primary function of the hypodermis layer of skin?

The primary function of the hypodermis, also known as the subcutaneous layer, is thermal insulation. This layer is composed mainly of adipose (fat) tissue and connective tissue, which helps to regulate body temperature by providing insulation against heat loss. The adipose tissue stores energy and creates a barrier that reduces the impact of cold environments on the body.

Additionally, the hypodermis serves as an important cushion to protect underlying muscles and bones from trauma. While it plays roles in energy storage and as a channel for larger blood vessels and nerves that extend to the skin, its primary function in terms of skin layers is to provide thermal insulation. Other layers of the skin contribute more to protection, sensation, and excretion, which are functions that are not primarily associated with the hypodermis.