Cross section of the skin

Illustration copyright 2000 by Nucleus Communications, Inc. All rights reserved. http://www.nucleusinc.com

There are two main skin layers:

• The outer layer (epidermis) has four sublayers. The skin cells (melanocytes) that develop into melanoma usually are found in the lower epidermis.
• The inner layer (dermis) has two sublayers, the papillary (first) and reticular (lower) layers.

The bottom layer shown in the picture (hypodermis) is not really part of the skin. It is a layer of connective tissue, fat cells, blood vessels, and nerves. The hypodermis is the connection between the skin and the structures under it, such as muscles.

Skin depth varies depending on location. It is thin on the neck, thick on the soles of the feet. Connective tissue, fat, muscles, and muscle covering (fascia) lie below the skin.