Skeleton

skeleton, the supportive framework of an animal body. The skeleton of invertebrates, which may be either external or internal, is composed of a variety of hard nonbony substances. The more complex skeletal system of vertebrates is internal and is composed of several different types of tissues that are known collectively as connective tissues. This designation includes bone and the various fibrous substances that form the joints, connect bone to bone and bone to muscle, enclose muscle bundles, and attach the internal organs to the supporting structure. For a more detailed discussion of the human skeleton, see skeletal system, human.