A joint (articulation) is formed when two bones make contact with each other.
Some joints, such as the knee and shoulder, allow a good deal of movement. Other
joints, such as the joints of the skull, allow little or no movement. The bones of movable
joints do not actually touch each other. They are separated by fibrous tissue that
prevents the bones from rubbing against each other. Ligaments, which are composed
of very strong fibrous material, hold the ends of the two bones in place (see figure 1-2).
Figure 1-2. Example of a joint.