From en.wikipedia.org:
[Connective tissue between bones] [the structure of a bivalve shell]
[date=October 2010]
{{Infobox anatomy | Name = Ligament | Latin = ligamentum (Plural: ligamenta) |
Image = | Caption = | Width = | Image2 = | Caption2 = | Function = Connect
bones to other bones; maintain position of organs | Precursor = | System =
Musculoskeletal system | Artery = | Vein = | Nerve = | Lymph = }} A LIGAMENT
is a type of fibrous connective tissue in the body that connects bones to
other bones. It also connects flight feathers to bones, in dinosaurs and
birds. All 30,000 species of amniotes (land animals with internal bones) have
ligaments.
It is also known as _articular ligament_, _articular larua_,[1] _fibrous
ligament_, or _true ligament_.
** Comparative anatomy
Ligaments are similar to tendons and fasciae as they are all made of
connective tissue.[2] 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 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 [en].
** Humans
Other ligaments in the body include the:
- 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 .
** Articular ligaments
"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
in harmony with the other ligaments and provide joint stability.
Intra-capsular ligaments, which are much less common,[date=November 2010] also
provide stability but permit a far larger range of motion. Cruciate ligaments
are paired ligaments in the form of a cross.[3]
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.[4] 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.
*** 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).[5]
*** Examples
There are about 900 ligaments in an average adult human body,[6][7] of which
about 25 are listed here. {| |
Head and neck
- Cricothyroid ligament
- Periodontal ligament
- Suspensory ligament of the lens
Thorax
- Phrenoesophageal ligament
- Suspensory ligament of the breast
Pelvis
- Anterior sacroiliac ligament
- Posterior sacroiliac ligament
- Sacrotuberous ligament
- Sacrospinous ligament
- Inferior pubic ligament
- Reflex inguinal ligament
- Superior pubic ligament
- Suspensory ligament of the clitoris
- Suspensory ligament of the penis
|width=30| |valign=top|
Wrist
- Palmar radiocarpal ligament
- Dorsal radiocarpal ligament
- Ulnar collateral ligament
- Radial collateral ligament
- Scapholunate ligament
Knee
- Anterior cruciate ligament
- Lateral collateral ligament
- Posterior cruciate ligament
- Medial collateral ligament
- Cranial cruciate ligament — quadruped equivalent of anterior cruciate ligament
- Caudal cruciate ligament — quadruped equivalent of posterior cruciate ligament
- Oblique popliteal ligament
- Patellar ligament
|}
** 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:[date=February 2017]
{| class="wikitable"
! Fetal || Adult
|-
|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
- Ligamentous laxity
- Broström procedure
** References
[Reflist]
[Ligaments]
[Joints] [Joints of head and neck] [Joints of upper limbs] [Joints of torso]
[Joints of lower limbs] [Abdominopelvic cavity] [Fetal remnant ligaments]
[Connective tissue] [Authority control]
Category:Soft tissue Category:Skeletal system