ligament
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A ligament is the
fibrous connective tissue Connective tissue is one of the four primary types of animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, ...
that connects
bone A bone is a rigid organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic ...
s to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal ligament: a fold of
peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesotheli ...
or other membranes. * Fetal remnant ligament: the remnants of a
fetal A fetus American and British English spelling differences#ae and oe, or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of developm ...
tubular structure. *
Periodontal ligament The periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits. It inserts into root cementum one side and onto alveolar bo ...
: a group of fibers that attach the
cementum Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.Illustrated Dental Embryology, Histology, a ...
of
teeth A tooth (plural, : teeth) is a hard, calcification, calcified structure found in the jaws (or mouths) of many vertebrates and used to Mastication, break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with ...
to the surrounding alveolar bone. Ligaments are similar to
tendon A tendon or sinew is a tough, high-tensile-strength band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skele ...
s and fasciae as they are all made of
connective tissue Connective tissue is one of the four primary types of animal tissue (biology), tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Con ...
. The differences among 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 A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...
of the
human body The human body is the structure of a Human, human being. It is composed of many different types of Cell (biology), cells that together create Tissue (biology), tissues and subsequently organ systems. They ensure homeostasis and the life, viabi ...
. 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 .


Articular ligaments

"Ligament" most commonly refers to a band of
dense regular connective tissue Dense regular connective tissue (DRCT) provides connection between different tissues in the human body. The collagen fibers in dense regular connective tissue are bundled in a parallel fashion. DRCT is divided into white fibrous connective tissue ...
bundles made of
collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...
ous fibers, with bundles protected by dense irregular connective tissue sheaths. Ligaments connect bones to other bones to form
joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...
s, while
tendon A tendon or sinew is a tough, high-tensile-strength band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skele ...
s connect bone to
muscle Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other ...
. Some ligaments limit the mobility of articulations or prevent certain movements altogether. Capsular ligaments are part of the articular capsule that surrounds
synovial joint A synovial joint, also known as diarthrosis, joins bones or cartilage with a fibrous joint capsule that is continuous with the periosteum of the joined bones, constitutes the outer boundary of a synovial cavity, and surrounds the bones' articulat ...
s. They act as mechanical reinforcements. Extra-capsular ligaments join in harmony with the other ligaments and provide joint stability. Intra-capsular ligaments, which are much less common, also provide stability but permit a far larger range of motion. Cruciate ligaments are paired ligaments in the form of a cross. Ligaments are
viscoelastic In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both Viscosity, viscous and Elasticity (physics), elastic characteristics when undergoing deformation (engineering), deformation. Viscous mate ...
. 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. 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 the characteristic of 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 Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of articular cartilage, joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of ...
.


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 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. Artificial ligaments are a synthetic material composed of a polymer, such as polyacrylonitrile fiber, polypropylene, PET (polyethylene terephthalate), or polyNaSS poly(sodium styrene sulfonate).


Examples

;Head and neck * Cricothyroid ligament *
Periodontal ligament The periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits. It inserts into root cementum one side and onto alveolar bo ...
* Suspensory ligament of the lens ;Thorax * Phrenoesophageal ligament * Suspensory ligament of the breast ;Pelvis * Anterior sacroiliac ligament * Posterior sacroiliac ligament *
Sacrotuberous ligament The sacrotuberous ligament (great or posterior sacrosciatic ligament) is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends. Structure It runs from the sacrum (the lower ...
*
Sacrospinous ligament The sacrospinous ligament (small or anterior sacrosciatic ligament) is a thin, triangular ligament in the human pelvis. The base of the ligament is attached to the outer edge of the sacrum and coccyx, and the tip of the ligament attaches to the is ...
* Inferior pubic ligament * Superior pubic ligament *
Suspensory ligament of the penis The suspensory ligament of the penis is attached to the pubic symphysis, which holds the penis close to the pubic bone and supports it when erection, erect. The ligament does not directly connect to the Corpus cavernosum penis, but may still play ...
;Wrist * Palmar radiocarpal ligament * Dorsal radiocarpal ligament *
Ulnar collateral ligament Ulnar collateral ligament (or UCL), may refer to: * Ulnar carpal collateral ligament * Ulnar collateral ligament of elbow joint * Ulnar collateral ligament of thumb {{Short pages monitor