Skin Overview (38 CFR 4.118)

The skin is a large, heavy, complex organ consisting of millions of specialized cells associated with many vital functions and constituting about 15% of body weight it is also known as the integumentary system. The skin, hair, nails and glands are units of the integumentary system.

The basic overall functions of the skin are to hold the body together and to protect inner organs, bones, muscles and blood vessels. Specific functions of the skin include: protection against trauma, injurious substances, invasion of microorganisms and excessive loss of fluid and electrolytes; regulation of body temperature and blood pressure; reception of sensory stimuli; synthesis of Vitamin D; and excretion of sweat.

The skin is composed of three layers; the epidermis, dermis and subcutaneous tissue.

The top layer of skin is the epidermis. The epidermis varies in thickness, dependent upon the area of the body covered. For example, the epidermis is thin on the eyelids and many times thicker on the palms and soles of the feet. The epidermis supports blood vessels, lymph vessels, nerves and the appendages of the skin (hair, nails, and glands).

The layer beneath and cemented to the epidermis is known as the dermis. The dermis constitutes the principle mass of the skin. Blood vessels, nerves, lymphatic vessels, hair follicles, involuntary muscles and sebaceous and sweat glands are found in the dermis.

The subcutaneous layer consists largely of fat. It attaches the skin to underlying muscle and bone, and blood vessels and nerves supplying the skin run through this layer. This layer serves to support, nourish, insulate, and cushion the skin.