ABSTRACT
The vertebrate skeletal system or passive locomotor apparatus is composed of a bony or cartilaginous framework that is able to bear body weight in these animals. Whereas the endoskeleton of vertebrates is capable of gradual growth along with the rest of the body, the exoskeleton of insects is shed off periodically as the insect increases in size. During early embryological development, the vertebral column of vertebrates passes through the notochord stage that is not yet bone or cartilaginous tissue. The skeletal and muscular systems are also known as the locomotor apparatus and form a complete structural unit. The action of the skeletal system is also complemented by connective tissue elements such as ligaments that are made of dense regular connective tissue. The presence of joints at points of skeletal contact makes it possible for movement to occur.
