Flat bone
Flat bone | |
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Details | |
Identifiers | |
Latin | os planum |
TA98 | A02.0.00.013 |
TA2 | 371 |
FMA | 7476 |
Anatomical terms of bone |
Flat bones are bones whose principal function is either extensive protection or the provision of broad surfaces for muscular attachment. These bones are expanded into broad, flat plates,[1] as in the cranium (skull), the ilium, ischium, and pubis (pelvis), sternum and the rib cage. The flat bones are: the
These bones are composed of two thin layers of
Ossification in flat bones
Ossification is started by the formation of layers of undifferentiated connective tissue that hold the area where the flat bone is to come. On a baby, those spots are known as fontanelles. The fontanelles contain connective tissue stem cells, which form into osteoblasts, which secrete calcium phosphate into a matrix of canals. They form a ring in between the membranes, and begin to expand outwards. As they expand they make a bony matrix.
This hardened matrix forms the body of the bone. Since flat bones are usually thinner than the
After the bone is completely ossified, the osteoblasts retract their calcium phosphate secreting tendrils, leaving tiny canals in the bony matrix, known as
A third type of bone cell found in flat bones is called an osteoclast, which destroys the bone using enzymes. There are three reasons that osteoclasts are normally used: the first is for the reparation of bones after a break. They destroy sections of bone that protrude or make reformation difficult. They are also used to obtain necessary calcium that osteoclasts are used is for growing. As the bone grows, its shape changes. The osteoclasts dissolve the part of the bone that must change.[2]
Additional images
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Flat bones in human skeleton. (shown in red)
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Flat bones inhuman skull. (shown in red)
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Classification of bones by shape.
References
This article incorporates text in the public domain from page 79 of the 20th edition of Gray's Anatomy (1918)
This article needs additional citations for verification. (November 2010) |
- ^ a b c d e Gray's Anatomy (1918). (See infobox)
- ISBN 978-0-07-282953-2.