The bones of the human skeleton are classified by their shape: long bones, short bones, flat bones, sutural bones, sesamoid bones, and irregular bones (Figure 1). Human anatomy basics: The skeletal system, Types Of Joints – Classification of Joints in the Human Body. feb22thing87 PLUS. Immature osteogenic cells are found in the deep layers of the periosteum and the marrow. The mineral salts primarily include hydroxyapatite, a mineral formed from calcium phosphate. This system allows nutrients to be transported to the osteocytes and wastes to be removed from them. You may not have known that your bones have so many jobs. Most bones contain compact and spongy osseous tissue, but their distribution and concentration vary based on the bone’s overall function. Flat bones are thin and relatively broad bones that are found where extensive protection of organs is required or where broad surfaces of muscle attachment are required. As described earlier, canaliculi connect with the canaliculi of other lacunae and eventually with the central canal. Running down the center of each osteon is the central canal, or Haversian canal, which contains blood vessels, nerves, and lymphatic vessels. Examples of irregular bones are the vertebrae, hip bones, and several skull bones. A long bone is one that is cylindrical in shape, being longer than it is wide. Flat bones serve as points of attachment for muscles and often protect internal organs. A long bone has two parts: the diaphysis and the epiphysis. It can be found under the periosteum and in the diaphyses of long bones, where it provides support and protection. Long bones function as levers; they move when muscles contract. Learn types of bones with free interactive flashcards. Osteocytes maintain the mineral concentration of the matrix via the secretion of enzymes. These normally have bits that stick out, known as projections. The form collects name and email so that we can add you to our newsletter list for project updates. Sesamoid bones develop inside tendons and may be found near joints at the knees, hands, and feet. There are five major types of bones in the skeletal system. The dynamic nature of bone means that new tissue is constantly formed, and old, injured, or unnecessary bone is dissolved for repair or for calcium release. Many facial bones, particularly the ones containing sinuses, are classified as irregular bones. Long bones are longer than they are wide and have a shaft and two ends. Meet Your Muscles: How muscles are named. In addition, the spaces in some spongy bones contain red marrow, protected by the trabeculae, where hematopoiesis occurs. A short bone is one that is cube-like in shape, being approximately equal in length, width, and thickness. Compact bone is the denser, stronger of the two types of bone tissue (Figure 6.10). The hollow region in the diaphysis is called the medullary cavity, which is filled with yellow marrow. Irregular bones are bones with complex shapes. The type and characteristics of a given joint determine its degree and type of movement. The structure of a long bone allows for the best visualization of all of the parts of a bone (Figure 6.7). The long bones of the upper body include the clavicle, humerus, radius, ulna, metacarpals, and phalanges, whereas in the lower body there are the femur, tibia, fibula, metatarsals, and phalanges. As the secreted matrix surrounding the osteoblast calcifies, the osteoblast become trapped within it; as a result, it changes in structure and becomes an osteocyte, the primary cell of mature bone and the most common type of bone cell. http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@7.1@7.1. The patellae are sesamoid bones. Shown are different types of bones: flat, irregular, long, short, and sesamoid. 8 terms. Generally, they are made up of two types of bone tissue: Short bones are cube shaped and much smaller in size. Figure 2. There are different types of fractures and symptoms include pain, swelling, and discoloration of the skin around the injured area. Their shape, size, and proportion of bone tissue determine their classification. For example, the bones of the wrist (carpals) and ankle (tarsals) are short bones (Figure 1). Each epiphysis meets the diaphysis at the metaphysis, the narrow area that contains the epiphyseal plate (growth plate), a layer of hyaline (transparent) cartilage in a growing bone. They can communicate with each other and receive nutrients via long cytoplasmic processes that extend through canaliculi (singular = canaliculus), channels within the bone matrix. Compact bone is dense so that it can withstand compressive forces, while spongy (cancellous) bone has open spaces and supports shifts in weight distribution. Although bone cells compose a small amount of the bone volume, they are crucial to the function of bones. These osteogenic cells are undifferentiated with high mitotic activity and they are the only bone cells that divide. Each osteon is composed of concentric rings of calcified matrix called lamellae (singular = lamella). A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. The presence, location and quantity of sesamoid bones varies considerably from person to person. They may be found between the flat bones of the skull. Bone contains a relatively small number of cells entrenched in a matrix of collagen fibers that provide a surface for inorganic salt crystals to adhere. 22 terms. The trabeculae may appear to be a random network, but each trabecula forms along lines of stress to provide strength to the bone.