Ligament

Ligament
Diagram of the right knee.
Typical joint
Latin	Ligamentum (Plural: Ligamenta)

In anatomy, a ligament is the fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua,^[1] fibrous ligament, or true ligament.

Ligament can also refer to:

• Peritoneal ligament: a fold of peritoneum or other membranes.
• Fetal remnant ligament: the remnants of a fetal tubular structure.
• Periodontal ligament: a group of fibers that attach the cementum of teeth to the surrounding alveolar bone.

The study of ligaments is known as desmology (from Greek δεσμός, desmos, "bond"; and -λογία, -logia).

Ligaments are similar to tendons and fasciae as they are all made of connective tissue. The differences in them are in the connections that they make; ligaments connect one bone to another bone, tendons connect muscle to bone and fasciae connect muscles to other muscles. These are all found in the skeletal system of the human body. Ligaments cannot usually be regenerated naturally, however there are periodontal ligament stem cells located near the periodontal ligament which are involved in the adult regeneration of periodontal ligament.

Articular ligaments

"Ligament" most commonly refers to a band of tough, fibrous dense regular connective tissue bundles, made of attenuated collagenous fibers; with said bundles protected by dense irregular connective tissue sheaths. Ligaments connect bones to other bones to form a joint. They do not connect muscles to bones; that is the job of tendons. Some ligaments limit the mobility of articulations, or prevent certain movements altogether.

Capsular ligaments are part of the articular capsule that surrounds synovial joints. They act as mechanical reinforcements. Extra-capsular ligaments join together in harmony with the other ligaments and provide joint stability. Intra-capsular ligaments, which are much less common,^{[citation needed]} also provide stability but permit a far larger range of motion. Cruciate ligaments occur in pairs of three.

Ligaments are viscoelastic. They gradually shrink when under tension, and return to their original shape when the tension is removed. However, they cannot retain their original shape when compassed past a certain point or for a prolonged period of time. This is one reason why dislocated joints must be set as quickly as possible: if the ligaments lengthen too much, then the joint will be weakened, becoming prone to future dislocations.^{[citation needed]} Athletes, gymnasts, dancers, and martial artists perform stretching exercises to lengthen their ligaments, making their joints more supple.

The term hypermobility refers to people with more-elastic ligaments, allowing their joints to stretch and contort further; this is sometimes still called double-jointedness.

The consequence of a broken ligament can be instability of the joint. Not all broken ligaments need surgery, but, if surgery is needed to stabilise the joint, the broken ligament can be repaired. Scar tissue may prevent this. If it is not possible to fix the broken ligament, other procedures such as the Brunelli procedure can correct the instability. Instability of a joint can over time lead to wear of the cartilage and eventually to osteoarthritis.

Examples

Peritoneal ligaments

Certain folds of peritoneum are referred to as ligaments. Examples include:

• The hepatoduodenal ligament, that surrounds the hepatic portal vein and other vessels as they travel from the duodenum to the liver.
• The broad ligament of the uterus, also a fold of peritoneum.

Fetal remnant ligaments

Certain tubular structures from the fetal period are referred to as ligaments after they close up and turn into cord-like structures:^{[citation needed]}

See also

• Broström procedure

References

1. ↑ "ligament" at Dorland's Medical Dictionary

Wikimedia Commons has media related to Ligaments.