They are the major components of the ribs as well as the shoulder blades and flat bones of the skull. Most of the short flat bones of the skeleton are also composed of spongy bones. Spongy bones show relatively high metabolic activity as well. The spongy bones are transformed to the compact bones by the action of osteoblasts. Osteoblasts deposit new bone matrix around the trabeculae.
Therefore, the space between trabeculae become limited eventually. Compact Bone: Compact bone is the non-cancellous portion of a bone, which largely consists of closely packed osteons and forms the hard exterior of the bone.
Spongy Bone: Spongy bone is the osseous tissue, which fills the interior cavity of bones, consisting of mineralized bars called trabeculae. Compact Bone: Compact bones are also called cortical bones. Spongy Bone: Spongy bones are also called cancellous or trabecular bones. Compact Bone: Compact bones are made up of osteons. Spongy Bone: Spongy bones are made up of trabeculae. Compact Bone: Compact bones do not have spaces between lamellae. Spongy Bone: Spongy bones consist of spaces between lamellae.
Compact Bone: Compact bone has a marrow cavity. Spongy Bone: Spongy bone does not have a marrow cavity. Compact Bone: There is a high amount of Calcium in compact bones.
Spongy Bone: There is a very low amount of Calcium in spongy bones. Compact Bone: Compact bones are cylindrical. Compact Bone: Compact bones contain yellow bone marrow. Spongy Bone: Spongy bones contain red bone marrow. Compact Bone: Compact bones form major parts of the long bones such as arms and legs. Spongy Bone: Spongy bones form major parts of the short bones such as wrists and ankles.
Spongy Bone: Spongy bones are softer and more porous. Compact Bone: Compact bones occur in the inner surface of a bone. Spongy Bone: Spongy bones occur in the outer layers of a bone.
Compact Bone: Compact bones can withstand the weight of up to pounds. Spongy Bone: Spongy bones are unable to withstand high weights. Compact Bone: Compact bones provide structural support to the body. Instead, it consists of trabeculae , which are lamellae that are arranged as rods or plates.
Red bone marrow is found between the trabuculae. Blood vessels within this tissue deliver nutrients to osteocytes and remove waste. The red bone marrow of the femur and the interior of other large bones, such as the ilium, forms blood cells. Figure 2. Trabeculae in spongy bone are arranged such that one side of the bone bears tension and the other withstands compression.
Spongy bone reduces the density of bone and allows the ends of long bones to compress as the result of stresses applied to the bone. Spongy bone is prominent in areas of bones that are not heavily stressed or where stresses arrive from many directions. The epiphyses of bones, such as the neck of the femur, are subject to stress from many directions. Imagine laying a heavy framed picture flat on the floor. You could hold up one side of the picture with a toothpick if the toothpick was perpendicular to the floor and the picture.
Now drill a hole and stick the toothpick into the wall to hang up the picture. In this case, the function of the toothpick is to transmit the downward pressure of the picture to the wall.
The force on the picture is straight down to the floor, but the force on the toothpick is both the picture wire pulling down and the bottom of the hole in the wall pushing up.
The toothpick will break off right at the wall. The neck of the femur is horizontal like the toothpick in the wall. The weight of the body pushes it down near the joint, but the vertical diaphysis of the femur pushes it up at the other end.
The neck of the femur must be strong enough to transfer the downward force of the body weight horizontally to the vertical shaft of the femur Figure 2. Bone consists of four types of cells: osteoblasts, osteoclasts, osteocytes, and osteoprogenitor cells. Osteoblasts are bone cells that are responsible for bone formation.
Osteoblasts synthesize and secrete the organic part and inorganic part of the extracellular matrix of bone tissue, and collagen fibers. Osteoblasts become trapped in these secretions and differentiate into less active osteocytes. Spongy cancellous bone is lighter and less dense than compact bone. Spongy bone consists of plates trabeculae and bars of bone adjacent to small, irregular cavities that contain red bone marrow.
The canaliculi connect to the adjacent cavities, instead of a central haversian canal, to receive their blood supply. It may appear that the trabeculae are arranged in a haphazard manner, but they are organized to provide maximum strength similar to braces that are used to support a building. The trabeculae of spongy bone follow the lines of stress and can realign if the direction of stress changes.
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