Body membranes, which cover surfaces, line body cavities, and form protective (and often lubricating) sheets around organs, fall into two major groups. They fall into two major groups: (1) epithelial membranes, which include the cutaneous, mucous, and serous membranes, and (2) connective tissue membranes, represented by synovial membranes. The cutaneous membrane, generally called the skin or integumentary system, will receive most of our attention in this chapter, but first we will consider the other body membranes.