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

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The mineral salts primarily incorporate hydroxyapatite, a mineral developed from calcium phosphate. Calcification is the process of deposition the mineral salts on the collagen fiber matrix that crystallizes and hardens the tissue. The process of calcification just occurs in the visibility of collagen fibers.

The skeletal of the human skeleton space classified by your shape: lengthy bones, quick bones, flat bones, sutural bones, sesamoid bones, and also irregular skeletal (Figure 19.16).

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

Long bones are longer than lock are broad and have a shaft and also two ends. The diaphysis, or central shaft, includes bone marrow in a marrow cavity. The rounded ends, the epiphyses, space covered v articular cartilage and also are filled with red bone marrow, i beg your pardon produces blood cells (Figure 19.17). Most of the body bones are lengthy bones—for example, the femur, tibia, ulna, and also radius. Exceptions to this include the patella and the skeleton of the wrist and also ankle.

Figure 19.17. The lengthy bone is spanned by articular cartilage at either end and also contains bone marrow (shown in yellow in this illustration) in the marrow cavity.

Short bones, or cuboidal bones, are bones that room the very same width and also length, providing them a cube-like shape. Because that example, the skeletal of the wrist (carpals) and also ankle (tarsals) are short bones (Figure 19.16).

Flat bones are thin and fairly broad bones that are uncovered where considerable protection of offal is required or where broad surfaces of muscle attachment room required. Examples of flat bones space the sternum (breast bone), ribs, scapulae (shoulder blades), and the roof that the skull (Figure 19.16).

Irregular bones are bones with facility shapes. These bones may have actually short, flat, notched, or ridged surfaces. Examples of rarely often rare bones are the vertebrae, i know good bones, and also several skull bones.

Sesamoid bones are small, level bones and are shaped an in similar way to a sesame seed. The patellae are sesamoid bones (Figure 19.18). Sesamoid bones build inside tendons and may be uncovered near joints at the knees, hands, and feet.

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

vice versa, compact bone tissue forms the outer layer of all bones, spongy bone or cancellous bone develops the inner great of every bones. Spongy bone organization does not contain osteons that constitute compact bone tissue. Instead, it consists of trabeculae, which are lamellae that room arranged as rods or plates. Red bone marrow is found between the trabuculae. Blood vessels in ~ this tissue deliver nutrients come osteocytes and remove waste. The red bone marrow that the femur and also the interior of other huge bones, such together the ileum, develops blood cells.

Spongy bone reduce the thickness of bone and allows the end of long bones come compress together the result of stresses used to the bone. Spongy bone is significant in areas of skeletal that room not heavily stressed or wherein stresses arrive from many directions. The epiphyses that bones, such together the neck that the femur, are subject to tension from many directions. Imagine laying a hefty framed photo flat top top the floor. You can hold up one next of the picture with a toothpick if the toothpick was perpendicular to the floor and also the picture. Now drill a hole and also stick the toothpick right into the wall to cave up the picture. In this case, the duty of the toothpick is to transmit the downward push of the photo to the wall. The force on the photo is directly down to the floor, however the pressure on the toothpick is both the picture wire pulling down and also the bottom the the feet in the wall pushing up. The toothpick will certainly break off ideal at the wall.

The neck of the femur is horizontal favor the toothpick in the wall. The load of the body pushes it down close to the joint, yet the vertical diaphysis the the femur pushes the up at the other end. The neck of the femur must 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 room arranged such that one next of the bone bears tension and also the other withstands compression.