They are the rigid part of the locomotor system, it consists of the bone and skeleton system, there are approximately 206 bones in the human body, their growth goes from birth and they are little calcified, childhood and adolescence lead to their almost total growth. Due to their shape, they are differentiated by three types of bones: The flat bones that predominate in length, with an elongated middle part, the diaphysis that contains a cavity inside, the medullary cavity that surrounds the compact tissue.
The epiphyses which is formed by a thin layer of compact bone. The broad or flat bones predominate in length and width, differentiating an external or diploe area and two external and internal layers; examples of this are the parietal and frontal bones of the skull.
The short bones with their three dimensions practically equal, for that reason they have great resistance although they are of little mobility like the bones of the wrist. The bony eminences or processes are the protruding parts of the bone surface, being articular or non-articular; This depends on whether it is part of the joint, the non-articular ones serve for the insertion of muscles or ligaments, being named according to their shape protrusions, tuberosities, lines, crest among others.
Making body movements possible through push actions and levers. The bone cavities are also in being articular or not being articular, which if they host the corresponding bony eminences, the non-articular ones house soft parts such as organs, tendons, arteries to which they give protection; receiving various names such as pits, furrows, channels, among others and they are cavities filled with air. The orifices and bone conduits are of transmission or nutrition, passing through them nervous structures or arteries and veins that contribute substances to the bone.
Bones have an internal bony constitution of different parts: The periosteum is the outermost, vascularized layer that nourishes the bone and covers all the bone on its surface except the articulated areas. The bone substance that contains bone tissue and two are distinguished; the spongy, which is formed by a three - dimensional network of bone spiers or trabeculae, is what delimits a labyrinth of intercommunicating spaces occupied by the bone marrow.
The compact bone that is more solid, which can only be seen well with a microscope, being the spongy spindle and the compact bone hard part of the bone and which calcium predominates in its composition. The bone marrow is a soft substance that fills the small cavities of the spongy tissue, and that in long bones is concentrated in its central cavity, we call it the medullary cavity; The active red marrow is in charge of making blood cells, that is, red blood cells, white blood cells and platelets. The inactive yellow marrow, formed by fat.
