MODULE 2.13
The Skeletal SystemYour skeletal system comprises all the bones, cartilage, tendons and ligaments
that make up your physical body. “Skeleton” is a Greek word meaning
“dried-up” body.
Bones, cartilage, tendons and ligaments are forms of connective tissue.
Bones consist of osteocytes or bone cells, which are embedded in calcified
extracellular compounds and substances called a matrix. This bed or matrix
contains the minerals of calcium phosphate and calcium carbonate, as well as
collagen (tough rope-like protein) fibers.
As previously stated, bones are formed from fibrous connective tissue.
You especially see this in the beginning stages of life (embryonic). As the
fetus develops, this connective tissue becomes dense and hardens, becoming
the skeletal system. Bones serve as protection for vital organs, and as
structural supports and functions.
Your physical body is composed of 206 bones (more or less):Head—29
Upper extremities—64
Trunk—51
Lower extremities—62TYPES OF BONES
Bones are classified by their shape and size, e.g., long bones, short bones, flat
or irregular bones.
LONG BONES — Longer than they are wide. Bones of the extremities
(arms, legs)
SHORT BONES — Somewhat as wide as they are long (e.g., ankle, wrist)
FLAT BONES — Flat bones are thin bones (e.g., skull, sternum, ribs )
IRREGULAR BONES — These bones come in different shapes and sizes
(e.g., facial, vertebrae)