Skeletal System
There are 206 bones in the human body. The axial skeleton consists of
the head, neck and trunk. There are eighty bones in the axial skeleton.
The appendicular skeleton consists of the extremities, and has 126 bones.
Functions of the skeletal system
Protection of the vital organs, erect posture and support for soft
tissue. The bones are levers for the attached muscles and marrow of bones
produses blood cells and platelets. Bones store minerals and fat in some
areas.
Types of bones
Long bones have a shaft called a diaphysis and the two wider ends are
called the epiphysis. A typical example of a long bone is a leg bone.
A short bone is about the same length as it's width. The feet and hands
have many short bones. Another type of bone is a flat bone. They are thin
and usually bent. A rib is a thin bone. There is another type of bone
called an irregular bone which are bones that are many irregular shapes.
Bones are composed of collagen, calcium and potassium. Wolff's law states
that bones can become more dense to adjust to strss placed on it. People
who participate in strength trainin will have theri bones become more
dense. Sedentary people will have bones that are less dense.
Articulations
Aticulations are joints. Joints are linked together by ligaments.
There are 3 catogories of joints.
-Fibrous Joints- Fibrous joints do not have a joint cavity. They are held
together by fibrous tissue. Fibrous joints have little or no movement.
-Cartilaginous Joints- Bones are connected by cartilage. There is little
or no movement.
-Synovial Joints- Synovial joints have point cavities so they have movement.
Most joints in the body are synovial joints.
Factors that limit the movement of synovial joints
Ligament tension, poor flexibility, joints touching the soft tissues.
Here are a few different types of movements made by synovial joints:
Uniplantar- moves like a hinge. Good example is an elbow
Biplantar- Two axes of rotation. Example is the knee, hand
Multiplantar- Three axes of motion. Like the hip or shoulders.
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