Bone, or osseous tissue, is a connective tissue that constitutes the endoskeleton. The contains devoted cells and a procession of mineral salts and also collagen fibers.

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The mineral salt primarily encompass hydroxyapatite, a mineral formed from calcium phosphate. Calcification is the process of deposition that mineral salt on the collagen fiber matrix that crystallizes and also hardens the tissue. The process of calcification just occurs in the presence of collagen fibers.

The skeleton of the person skeleton are classified by their shape: lengthy bones, quick bones, flat bones, sutural bones, sesamoid bones, and also irregular skeleton (Figure 19.16).

Figure 19.16. Displayed are different types of bones: flat, irregular, long, short, and sesamoid.

Long bones are much longer than castle are wide and have actually a shaft and also two ends. The diaphysis, or main shaft, consists of bone marrow in a marrow cavity. The rounded ends, the epiphyses, room covered v articular cartilage and are filled v red bone marrow, i m sorry produces blood cells (Figure 19.17). Many of the body bones are long bones—for example, the femur, tibia, ulna, and also radius. Exception to this encompass the patella and the bones of the wrist and also ankle.

Figure 19.17. The long bone is spanned by articular cartilage at one of two people end and contains bone marrow (shown in yellow in this illustration) in the marrow cavity.

Short bones, or cuboidal bones, are bones that are the exact same width and length, offering them a cube-like shape. For example, the skeleton of the wrist (carpals) and ankle (tarsals) are quick bones (Figure 19.16).

Flat bones room thin and fairly broad bones the are found where comprehensive protection of organs is compelled or where wide surfaces that muscle attachment room required. Examples of level bones room the sternum (breast bone), ribs, scapulae (shoulder blades), and the roof the the skull (Figure 19.16).

Irregular bones space bones with facility shapes. This bones may have short, flat, notched, or ridged surfaces. Instances of rarely often, rarely bones room the vertebrae, i know well bones, and also several skull bones.

Sesamoid bones are small, flat bones and also are shaped similarly to a sesame seed. The patellae space sesamoid bones (Figure 19.18). Sesamoid bones develop inside tendons and may be uncovered near joints in ~ the knees, hands, and feet.

Figure 19.18. The patella the the knee is an instance of a sesamoid bone.
Figure 19.19. Compact bone tissue consists of osteons that room aligned parallel to the long axis of the bone, and the Haversian canal that consists of the bone’s blood vessels and also nerve fibers. The inner layer of bones is composed of spongy bone tissue. The little dark ovals in the osteon represent the living osteocytes. (credit: alteration of occupational by NCI, NIH)

conversely, compact bone tissue forms the external layer of all bones, spongy bone or cancellous bone develops the inner class of every bones. Spongy bone organization does not contain osteons the constitute compact bone tissue. Instead, it is composed of trabeculae, which space lamellae that space arranged as rods or plates. Red bone marrow is found in between the trabuculae. Blood vessels within this tissue deliver nutrients come osteocytes and also remove waste. The red bone marrow that the femur and the inner of other large bones, such together the ileum, develops blood cells.

Spongy bone reduces the thickness of bone and enables the ends of long bones to compress together the an outcome of stresses used to the bone. Spongy bone is prominent in locations of skeleton that space not heavily stressed or where stresses arrive from numerous directions. The epiphyses of bones, such together the neck the the femur, are subject to anxiety from plenty of directions. Imagine laying a hefty framed snapshot flat on the floor. You could hold increase one side of the snapshot with a toothpick if the toothpick to be perpendicular come the floor and the picture. Currently drill a hole and stick the toothpick into the wall to hang up the picture. In this case, the duty of the toothpick is to transmit the downward push of the snapshot to the wall. The force on the picture is straight down to the floor, however the pressure on the toothpick is both the snapshot wire pulling down and also the bottom the the feet in the wall pushing up. The toothpick will break off appropriate at the wall.

The neck that the femur is horizontal like the toothpick in the wall. The load of the human body pushes it down close to the joint, however the upright diaphysis of the femur pushes that up in ~ the various other end. The neck that the femur have to be solid enough to deliver the downward force of the body weight horizontally come the vertical shaft of the femur (Figure 19.20).

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Figure 19.20. Trabeculae in spongy bone space arranged such that one side of the bone bear tension and the other withstands compression.