Bones

      As you know, bones are a huge part of your body and play a major part in the things you do everyday. Your bones are pretty much the main thing that run your body. Your bones are connected to everything, and they help you move to do the everyday things that you do.
       There is more to bones than just bones though. There is skeletal cartilage which contains no blood vessels, and is surrounded by the perichondrium that resists outward expansion. There are three types of cartilage and they are- hyaline, elastic, and fibrocartilage.  There are also different growths of cartilage. There is appositional, and interstitial. Appositional is where the cells in the perichondrium secrete matrix are against the external face of existing cartilage. Interstitial is where the lacunae-bound chondrocytes inside the cartilage divide and secrete new matrix, expanding the cartilage from within. Calification of cartilage occurs during normal bone growth and during old age.

     There are two classifications of the bones and they are Axial skeleton, and Appendicular skeleton. Axial are bones of the skull, vertebral column, and bones that are in the rib cage. Appendicular are bones that are the upper and lower limbs, shoulder, and hip bones. There are also bones that are classified by their shape. There are long bones, which are longer than they are wide, short bones, which are cube shaped bones like the wrist and ankle. They are also bones that form within tendons. Flat bones are thin flattened bones that are curved a little. Mostly in the sternum and skull. Irregular bones are bones with complicated shapes such as the vertebrae and the hip. 

      Bones have many functions. Bones are defiantly here for support, forming the frames that support the body and protect soft organs that are in the body. They Protect. The provide a case that protects the brain, spinal cord, and vital organs. The help you to move, providing levers for your muscles. Believe it or not, your bones also store minerals, mostly calcium and phosphorus. Your blood cells also form in your bones. Hematopoiesis occurs in the marrow cavities of your bones. 

      Your bones can be classified as two different of textures. There is compact bone, which is the dense outer layer, and there is spongy bone which is honeycomb trabeculae filled with yellow bone marrow.

Your bones have membranes. Periosteum, and Endosteum. Periosteum is a double layered protective membrane. THe outer fibrous layer is dense regular connective tissue, the inner osteogenic layer is made up of osteoblasts and osteoclasts. It is richly supplied with nerve fibers, blood, and lymphatic vessels that enter the bone via nutrient for mania. They are secured to underlying bone by Sharpey's fibers. Endosteum is a delicate membrane covering internal surfaces of the bone. Red marrow is also in your bones. In babies, it is found in the medullary cavity and all the areas of spongy bone. In adults, it is found in the dipole of flat bones, and the head of the femur and humerus. 

      Your "Bones" begin to develop at week 8 of embryo development.