What is an example of a ligament and what is its purpose in the human body?
One example of a ligament is the anterior cruciate ligament (ACL).
A ligament is the tough, fibrous tissue that connects one bone to another bone to form a joint.
Ligaments serve three major functions:
1. Defining range of motion
Their primary function is to prevent movement that might damage a joint.
2. Protecting bones and joints
Ligaments are relatively elastic, so they can stretch and contract when necessary to absorb shock under stress.
Ligaments enable us to sense the position, location, and orientation of the body and its parts.
The largest joint in the body, the knee, is a complex joint that is essential for movement.
Several important ligaments hold the knee together and control its range of motion.
Anterior cruciate ligament (ACL)
The ACL and the posterior cruciate ligament (PCL) bridge the inside of the knee joint.
They form an "X" pattern that stabilizes the knee against front-to-back and back-to-front forces.
The ACL typically sprains during a sudden stop; a twist, pivot or change in direction; or extreme over-straightening.
Posterior cruciate ligament (PCL)
The PCL most often sprains because of a direct impact to the front of the knee, such as hitting the knee on the dashboard in a car crash or landing hard on a bent knee during sports.
Medial Collateral ligament (MCL)
The MCL supports the knee along the inner side of the leg.
It can be torn by a direct sideways blow to the outside of the knee or lower leg.
Lateral collateral ligament (LCL)
The LCL supports the outer side of the knee.
It is the least likely knee ligament to be sprained, because most LCL injuries are caused by a blow to the inside of the knee, and that area usually is shielded by the opposite leg.