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Nothing symbolizes death as much as a skull or skeleton. The dry bones presented
for laboratory study suggest that the skeleton is an inert scaffold for the
body, like the steel girders of a building. Seeing it in such a sanitized form
makes it easy to forget that the living skeleton is made of dynamic tissues,
full of cells–that it continually remodels itself and interacts physiologically
with all of the other organ systems of the body. The skeleton is permeated with
nerves and blood vessels, and it receives a blood flow of about 200 to 400 mL/min
in adults, attesting to its sensitivity and metabolic activity.
The skeletal system is composed of three types of organs-bones, cartilages,
and ligaments–tightly joined together to form a strong, flexible organ
system. Cartilage, the forerunner of most bones in embryonic and childhood
development, covers many joint surfaces in the mature skeleton. Ligaments
hold bones together at the joints and are discussed in chapter 10. Tendons
are structurally similar to ligaments but attach muscle to bone; they are discussed
with the muscular system in chapter 11.
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