Long Bones
The bones of the body come in a variety of sizes
and shapes. The four principal types of bones are
long, short, flat and irregular. Bones that are longer
than they are wide are called long bones. They consist
of a long shaft with two bulky ends or extremities.
They are primarily compact bone but may have a large
amount of spongy bone at the ends or extremities.
Long bones include bones of the thigh, leg, arm, and
forearm.
Short Bones
Short bones are roughly cube shaped with vertical
and horizontal dimensions approximately equal. They
consist primarily of spongy bone, which is covered
by a thin layer of compact bone. Short bones include
the bones of the wrist and ankle.
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Flat Bones
Flat bones are thin, flattened, and usually curved. Most
of the bones of the cranium are flat bones.
Irregular Bones
Bones that are not in any of the above three categories are
classified as irregular bones. They are primarily spongy bone
that is covered with a thin layer of compact bone. The vertebrae
and some of the bones in the skull are irregular bones.
All bones have surface markings and characteristics that
make a specific bone unique. There are holes, depressions,
smooth facets, lines, projections and other markings. These
usually represent passageways for vessels and nerves, points
of articulation with other bones or points of attachment for
tendons and ligaments.
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