Biomedical Engineering Reference
In-Depth Information
Flat bone
Long bone
Irregular bone
Short bone
FIGURE 1.3
Illustration of bones classified based on geometric shapes.
and stability with little movement. They are roughly cube shaped
and have only a thin layer of compact bone surrounding a spongy
interior. They are found primarily in the feet and hands (carpal and
tarsal bones). Further examples of this class of bone include the
cuboid, cuneiform, scaphoid, and trapezoid bones, etc. Short bones
are used for elasticity and adaptability. When walking, the feet must
bear extreme amounts of weight and conform to endless varieties
of terrain. The arrangement of the bones and tissue allows the feet
almost to mold to these surfaces and to absorb shock.
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Flat bones.
Flat bones are flat in appearance and have two promi-
nent surfaces known as the anterior and posterior surfaces, which
are formed from compact bone to provide strength for protection
(see Figure 1.3). Their centers consist of cancellous (spongy) bones
and varying amounts of bone marrow. These bones resemble shal-
low plates and form boundaries of certain body cavities. An example
of a flat bone is the scapula (the shoulder blade), which protects sev-
eral structures in the back region. In general, the main function of
flat bones is to provide protection to the body's vital organs and to
provide a base for muscular attachment.
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Irregular bones.
As the name implies, the shape of these bones is irreg-
ular and they do not fit into any other shape category (Figure 1.3).
Typical examples of irregular bones are the vertebrae, sacrum, and
bones in the base of the skull. They consist primarily of cancellous
bone, with a thin outer layer of compact bone. The vertebrae have
a shape that allows them to protect the central nervous system,
