Despite advances in peripheral nerve repair techniques, complete functional recovery is seldom achieved. To understand the nerve’s regenerative capacity, it is necessary to understand its developmental and functional anatomy and its cellular constituents. This article serves to review the role of Schwann cell and myelination in normal and injured peripheral nerves. Schwann cells not only help to improve action potential conduction velocity, but recent studies have shown that these cells also play an important role in neural function. Schwann cell-mediated diseases such as type I Charcot-Marie-Tooth Disease, multiple sclerosis, and chronic nerve compression injury secondarily affect the function and organization of neurons to produce neural dysfunction.