Fascia
Every structure in your body is covered in a thin membrane called Fascia. The diagram below is a cross section of a nerve. As you can see a nerve is comprised of threadlike structures called axons.
   Each axon is wrapped in fascia and then groups of axons are wrapped together in fascia and so on. It is the same with every other structure in your body, big or small, it is wrapped in fascia. Fascia forms a connective covering that encapsulates your whole body.