GLOSSARY

A ball-and-socket joint is a triaxial synovial joint in which the spherical head of one bone fits into the cup-shaped socket of another, giving the greatest freedom of movement of any joint in the body.

Movements

Flexion and extension, abduction and adduction, internal and external rotation, and circumduction.

Examples

• Shoulder (glenohumeral) joint: a shallow socket; the most mobile but least stable joint in the body.
• Hip joint: a deep socket; more stable but with less range of motion.

Shoulder versus Hip