What does the prefix "epi-" mean in medical terms?

The prefix "epi-" in medical terminology means "upon" or "over." It is derived from the Greek term "epi," which conveys a sense of being on top of, or in addition to something. In medical context, this prefix is commonly used to describe anatomical locations or functions. For example, "epidermis" refers to the outer layer of the skin, indicating that it is the layer situated upon the underlying tissues. Similarly, "epicardium" denotes the layer of tissue that covers the heart, further illustrating how "epi-" signifies something that is positioned over or upon another structure. This understanding of "epi-" helps in the interpretation of various medical terms and their implications regarding location and relationship in the body.