http://www.ck12.org Chapter 1. Human Biology
1.7 Skeletal System Joints
- Describe the different types of joints and how they work.
Why does his knee hurt?
As you age, you might start noticing pain in your knees or elbows. These are examples of joints. Joints are the part
of the skeletal system that connect your bones. Joint pain is a common problem as people age.
Joints and How They Move
Ajointis a point at which two or more bones meet. There are three types of joints in the body:
1.Fixed jointsdo not allow any bone movement. Many of the joints in your skull are fixed (Figure1.11).2.Partly movable jointsallow only a little movement. Your backbone has partly movable joints between the
vertebrae (Figure1.12).3.Movable jointsallow the most movement.Movable joints are also the most common type of joint in your body. Your fingers, toes, hips, elbows, and knees
all provide examples of movable joints. The surfaces of bones at movable joints are covered with a smooth layer of
cartilage. The cartilage reduces friction between the bones. Four types of movable joints are shown below.