mastoid bone mastoid part of temporal bone. membrane bone (membranous bone) bone that develops within a connective tissue membrane, in contrast to cartilage bone. occipital bone the bone constituting the back and part of the base of the skull. See anatomic Table of Bones in the Appendices.one. 1. the hard, rigid form of connective tissue constituting most of the skeleton of vertebrates, composed chiefly of calcium salts. 2. any distinct piece of the skeleton of the body. See anatomic Table of Bones in the Appendices for regional and alphabetical listings of bones, and see color plates 1 and 2.