The human body is composed of soft tissues such as skin and internal organs and hard tissues which are the bones. There is also a third class of tissue in the human body that is composed of fibrous connective tissue. Most notable among these are the ligaments that connect bones to each other and help control movement of the body. Ligaments are often referred to as fibrous ligaments, true ligaments or articular ligaments. 

Function of Ligaments

Ligaments are in every joint in the body. That means that wherever two bones meet, ligaments are there to connect them. The elasticity of the fibrous ligaments allows them to change shape and lengthen under stress and then return to their original shapes. There are several distinct functions of ligaments in the human body.

1. Define Range of Motion

First, ligaments determine how much joints can move. The ligaments are the structures that keep a joint from becoming dislocated; that is, they limit how much a joint can move in any direction. This function serves to stabilize each joint. Typically, there may be several ligaments that work together to help define the range of motion for any joint. For example, spinal ligaments hold the vertebrae together and thus maintain the shape and limit the movement of the spine.

2. Protect Joints and Bones

Ligaments also function to protect the bones that form each joint. Because they are relatively elastic, ligaments can stretch and contract when necessary which allows them to absorb shock under stress. For example, the ligaments in the spine protect the vertebrae when you suddenly change your posture or lift a heavy object.

3. Proprioception

Finally, ligaments are part of the proprioception function in the human body. Proprioception refers to your ability to know the position of any joint in your body, thus maintaining the correct posture and movement of an individual. This function enables bones, muscles and ligaments to work together to make the joint work correctly and without injury.

Structure of Ligaments

Function of ligaments is not possible without its components. Ligaments are formed by long fibers of collagen. Collagen is composed of groups of proteins such as those found in skin and all connective tissue. The elasticity of collagen is what allows ligaments to stretch and then resume their normal shapes when the stress is relieved. In most ligaments, the collagen fibers are typically found in a cross-hatched pattern forming sheets of tissue that ensure that bones cannot move past their normal range of motion.

Ligaments Injuries and Treatments

The most common ligament injury is referred to as a sprain. This results when a ligament is stretched too much and is unable to return to its resting form. A ligament sprain is usually caused when you move a joint very suddenly or when you have not warmed up the ligaments prior to exercise. The extreme injury to a ligament is a tear or rupture. In this kind of injury, the ligament is stressed beyond its ability to stretch and results in a tear. This is the kind of injury that often occurs in knees of athletes when the anterior cruciate ligament, or ACL, is torn or ruptured. The blood supply to ligaments is very low, so these injuries can take a long time to heal.

With repeated over-stretching of a ligament, the ligament may become weaker. Because of this, the joint it supports may become weaker and more susceptible to injury. It is not unusual for your healthcare provider to immobilize a joint if you have an injured ligament. Tears and ruptures may require surgical correction.

To restore function of ligaments, the following video shows some rehabilitation techniques for one of the most common ligament injury--lateral collateral ligament injury:

Differences Between Ligaments and Tendons

Ligaments and tendons are both fibrous, connective tissues. The difference is that tendons attach muscles to bones or other tissues while ligaments attach bones to each other. The tendon is primarily responsible for moving a bone while the ligament is primarily responsible for holding joints together and providing stability of the joint. However, both structures are critical in making your joints move correctly and fluidly. When you injure a joint, it is very common to injure both ligaments and tendons.