Ligament

Last updated
Ligament
Details
System Musculoskeletal system
FunctionConnect bones to other bones; maintain position of organs
Identifiers
Latin Ligamentum (Plural: Ligamenta)
MeSH D008022
TA A03.0.00.034
FMA 30319
Anatomical terminology

A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as articular ligament, articular larua, [1] fibrous ligament, or true ligament. Other ligaments in the body include the:

Contents

Ligaments are similar to tendons 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 periodontist ligament.

The study of ligaments is known as desmology

Articular ligaments

Articular ligament. Ligament.jpg
Articular ligament.

"Ligament" most commonly refers to a band of dense regular connective tissue bundles made of collagenous fibers, with bundles protected by dense irregular connective tissue sheaths. Ligaments connect bones to other bones to form joints, while tendons connect bone to muscle. 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 are paired ligaments in the form of a cross. [2]

Ligaments are viscoelastic. They gradually strain when under tension and return to their original shape when the tension is removed. However, they cannot retain their original shape when extended past a certain point or for a prolonged period of time. [3] 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. 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.

Artificial ligaments

One of the most often torn ligaments in the body is the anterior cruciate ligament (ACL). The ACL is one of the ligaments crucial to knee stability and persons who tear their ACL often seek to undergo reconstructive surgery, which can be done through a variety of techniques and materials. One of these techniques is the replacement of the ligament with an artificial material. An artificial ligament is a reinforcing material that is used to replace a torn ligament, such as the ACL. Artificial ligaments are a synthetic material composed of a polymer, such as polyacrylonitrile fiber, polypropylene, PET (polyethylene terephthalate), or polyNaSS poly(sodium styrene sulfonate). [4]

Examples

Peritoneal ligaments

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

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 ]

FetalAdult
ductus arteriosus ligamentum arteriosum
extra-hepatic portion of the fetal left umbilical vein ligamentum teres hepatis (the "round ligament of the liver").
intra-hepatic portion of the fetal left umbilical vein (the ductus venosus) ligamentum venosum
distal portions of the fetal left and right umbilical arteries medial umbilical ligaments

See also

Related Research Articles

Knee Region around the kneecap

In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia, and one between the femur and patella. It is the largest joint in the human body. The knee is a modified hinge joint, which permits flexion and extension as well as slight internal and external rotation. The knee is vulnerable to injury and to the development of osteoarthritis.

Temporomandibular joint

The temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that its name is derived. This joint is unique in that it is a bilateral joint that functions as one unit. Since the TMJ is connected to the mandible, the right and left joints must function together and therefore are not independent of each other.

Tibia larger of the two bones of the leg below the knee for vertebrates

The tibia, also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates, and it connects the knee with the ankle bones. The tibia is found on the medial side of the leg next to the fibula and closer to the median plane or centre-line. The tibia is connected to the fibula by the interosseous membrane of the leg, forming a type of fibrous joint called a syndesmosis with very little movement. The tibia is named for the flute tibia. It is the second largest bone in the human body next to the femur. The leg bones are the strongest long bones as they support the rest of the body.

Pubic symphysis Cartilaginous joint that sits between and joins the left and right superior rami of the pubic bones

The pubic symphysis is a cartilaginous joint that sits between and joins the left and right superior rami of the pubic bones. It is located in front of and below the urinary bladder. In males, the suspensory ligament of the penis attaches to the pubic symphysis. In females, the pubic symphysis is intimately close to the clitoris. In normal adults it can be moved roughly 2 mm and with 1 degree rotation. This increases for women at the time of childbirth.

Sprain Damage to one or more ligaments in a joint

A sprain, also known as a torn ligament, is the stretching or tearing of ligaments within a joint, often caused by trauma abruptly forcing the joint beyond its functional range of motion. Ligaments are tough, inelastic fibers made of collagen that connect two or more bones to a joint and are important for joint stability and proprioception, which is the body's sense of limb position and movement. The majority of sprains are mild, causing minor swelling and bruising that can be resolved with conservative treatment. However, severe sprains involve complete tears, ruptures, or fractures, often leading to joint instability, severe pain, and decreased functional ability. These sprains require surgical fixation, prolonged immobilization, and physical therapy. Sprains can occur at any joint but most commonly occur in the ankle, knee, or wrist. An equivalent injury to a muscle or tendon is known as a strain.

Posterior cruciate ligament One of four major ligaments of the knee

The posterior cruciate ligament (PCL) is a ligament in each knee of humans and various other animals. It works as a counterpart to the anterior cruciate ligament (ACL). It connects the posterior intercondylar area of the tibia to the medial condyle of the femur. This configuration allows the PCL to resist forces pushing the tibia posteriorly relative to the femur.

Anterior cruciate ligament Type of cruciate ligament in the human knee

The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments in the human knee. The 2 ligaments are also called cruciform ligaments, as they are arranged in a crossed formation. In the quadruped stifle joint, based on its anatomical position, it is also referred to as the cranial cruciate ligament. The term cruciate translates to cross. This name is fitting because the ACL crosses the posterior cruciate ligament to form an “X”. It is composed of strong fibrous material and assists in controlling excessive motion. This is done by limiting mobility of the joint. The anterior cruciate ligament is one of the four main ligaments of the knee, providing 85% of the restraining force to anterior tibial displacement at 30 degrees and 90 degrees of knee flexion. The ACL is the most injured ligament of the four located in the knee.

Human musculoskeletal system Organ system that gives humans the ability to move by using their muscular and skeletal systems

The human musculoskeletal system is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provides form, support, stability, and movement to the body.

A soft tissue injury (STI) is the damage of muscles, ligaments and tendons throughout the body. Common soft tissue injuries usually occur from a sprain, strain, a one off blow resulting in a contusion or overuse of a particular part of the body. Soft tissue injuries can result in pain, swelling, bruising and loss of function.

Anterior cruciate ligament reconstruction Surgical process

Anterior cruciate ligament reconstruction is a surgical tissue graft replacement of the anterior cruciate ligament, located in the knee, to restore its function after an injury. The torn ligament can either be removed from the knee, or preserved before reconstruction an arthroscopic procedure. ACL repair is also a surgical option. This involves repairing the ACL by re-attaching it, instead of performing a reconstruction. Theoretical advantages of repair include faster recovery and a lack of donor site morbidity, but randomised controlled trials and long-term data regarding re-rupture rates using contemporary surgical techniques are lacking.

Dense connective tissue

Dense connective tissue, also called dense fibrous tissue, is a type of connective tissue with fibers as its main matrix element. The fibers are mainly composed of type I collagen. Crowded between the collagen fibers are rows of fibroblasts, fiber-forming cells, that generate the fibers. Dense connective tissue forms strong, rope-like structures such as tendons and ligaments. Tendons attach skeletal muscles to bones; ligaments connect bones to bones at joints. Ligaments are more stretchy and contain more elastic fibers than tendons. Dense connective tissue also make up the lower layers of the skin (dermis), where it is arranged in sheets.

Anterior cruciate ligament injury ligament injury near the knee

Anterior cruciate ligament injury is when the anterior cruciate ligament (ACL) is either stretched, partially torn, or completely torn. The most common injury is a complete tear. Symptoms include pain, a popping sound during injury, instability of the knee, and joint swelling. Swelling generally appears within a couple of hours. In approximately 50% of cases, other structures of the knee such as surrounding ligaments, cartilage, or meniscus are damaged.

Patellar ligament

The patellar ligament is the distal portion of the common tendon of the quadriceps femoris, which is continued from the patella to the tibial tuberosity. It is also sometimes called the patellar tendon as it is a continuation of the quadriceps tendon.

Triangular fibrocartilage

The Triangular fibrocartilage complex (TFCC) is formed by the triangular fibrocartilage discus (TFC), the radioulnar ligaments (RULs) and the ulnocarpal ligaments (UCLs).

Unhappy triad injury to the anterior cruciate ligament, medial collateral ligament, and meniscus

The unhappy triad, also known as a blown knee among other names, is an injury to the anterior cruciate ligament, medial collateral ligament, and meniscus. Analysis during the 1990s indicated that this 'classic' O'Donoghue triad is actually an unusual clinical entity among athletes with knee injuries. Some authors mistakenly believe that in this type of injury, "combined anterior cruciate and medial collateral ligament disruptions that were incurred during athletic endeavors" always present with concomitant medial meniscus injury. However, the 1990 analysis showed that lateral meniscus tears are more common than medial meniscus tears in conjunction with sprains of the ACL.

Articular capsule of the knee joint

The articular capsule of the knee joint is the wide and lax joint capsule of the knee. It is thin in front and at the side, and contains the patella, ligaments, menisci, and bursae of the knee. The capsule consists of an inner synovial membrane, and an outer fibrous membrane separated by fatty deposits anteriorly and posteriorly.

Genu recurvatum deformity in the knee joint

Genu recurvatum is a deformity in the knee joint, so that the knee bends backwards. In this deformity, excessive extension occurs in the tibiofemoral joint. Genu recurvatum is also called knee hyperextension and back knee. This deformity is more common in women and people with familial ligamentous laxity. Hyperextension of the knee may be mild, moderate or severe.

Posterolateral corner injuries of the knee are injuries to a complex area formed by the interaction of multiple structures. Injuries to the posterolateral corner can be debilitating to the person and require recognition and treatment to avoid long term consequences. Injuries to the PLC often occur in combination with other ligamentous injuries to the knee; most commonly the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). As with any injury, an understanding of the anatomy and functional interactions of the posterolateral corner is important to diagnosing and treating the injury.

Medial knee injuries

Medial knee injuries are the most common type of knee injury. The medial ligament complex of the knee is composed of the superficial medial collateral ligament (sMCL), deep medial collateral ligament (dMCL), and the posterior oblique ligament (POL). These ligaments have also been called the medial collateral ligament (MCL), tibial collateral ligament, mid-third capsular ligament, and oblique fibers of the sMCL, respectively. This complex is the major stabilizer of the medial knee. Injuries to the medial side of the knee are most commonly isolated to these ligaments. A thorough understanding of the anatomy and function of the medial knee structures, along with a detailed history and physical exam, are imperative to diagnosing and treating these injuries.

Artificial ligaments are devices used to replace damaged ligaments. Today, the most common use of artificial ligaments is in anterior cruciate ligament reconstruction. Although autotransplantation remains the most common method of ligament reconstruction, numerous materials and structures were developed to optimize the artificial ligament since its creation in the World War I era. Many modern artificial ligaments are made of synthetic polymers, such as polyethylene terephthalate. Various coatings have been added to improve the biocompatibility of the synthetic polymers. Early artificial ligaments developed in the 1980s were ineffective due to material deterioration. Currently, the Ligament Advanced Reinforcement System (LARS) artificial ligament has been utilized extensively in clinical applications. Tissue engineering is a growing area of research which aims to regenerate and restore ligament function.

References

  1. " ligament " at Dorland's Medical Dictionary
  2. Daniel John Cunningham (1918). Cunningham's text-book of anatomy (5th ed.). Oxford Press. p. 1593.
  3. R.A., Hauser; E.E., Dolan; H.J., Phillips; A.C., Newlin; R.E., Moore; B.A., Woldin (2013-01-23). "Ligament Injury and Healing: A Review of Current Clinical Diagnostics and Therapeutics" (PDF). The Open Rehabilitation Journal. 6 (1): 5. doi:10.2174/1874943701306010001.
  4. Lessim S, Migonney V, Thoreux P, Lutomski D, Changotade S. (June 2013). "PolyNaSS bioactivation of LARS artificial ligament promotes human ligament fibroblast colonisation in vitro". Biomed Mater Eng. 23 (4): 289–297. doi:10.3233/BME-130753. PMID   23798650.CS1 maint: uses authors parameter (link)