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In anatomy, the term ligament is used to denote three different types of structures:[1]
- Fibrous tissue that connects bones to other bones. They are sometimes called "articular ligaments"[2], "fibrous ligaments", or "true ligaments".
- A fold of peritoneum or other membrane
- The remnants of a tubular structure from the fetal period of life
The first meaning is most commonly what is meant by the term "ligament". After briefly discussing the other two types of ligaments, the remainder of this article will focus upon the first type.
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:
Articular ligaments
Diagrammatic section of a symphysis.
In its most common use, a ligament is a short band of tough fibrous dense regular connective tissue composed mainly of long, stringy collagen fibres. Ligaments connect bones to other bones to form a joint. (They do not connect muscles to bones; that is the function 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 bones together and provide joint stability.
Ligaments are only elastic; when under tension, they gradually lengthen. (Unlike tendons which are inelastic). 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 double-jointed refers to people who have more elastic ligaments, allowing their joints to stretch and contort further. The medical term for describing such double-jointed persons is hyperlaxity and double-jointed is a synonym of hyperlax.
The study of ligaments is known as desmology.
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 joined. 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
Knee
Head and neck
Pelvis
Thorax
Wrist
References
- ^ ligament at eMedicine Dictionary
- ^ l_09/12488504 at Dorland's Medical Dictionary
External links
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Joints and ligaments of lower limbs |
| Coxal/hip |
femoral (iliofemoral, pubofemoral, ischiofemoral) - head of femur - transverse acetabular |
| Knee-joint |
extracapsular: patellar - popliteal (oblique, arcuate) - collateral (medial/tibial, fibular/lateral)
intracapsular: cruciate (anterior, posterior) - menisci (medial, lateral) - transverse |
| Tibiofibular |
Superior tibiofibular: anterior of the head of the fibula - posterior of the head of the fibula
Inferior tibiofibular: anterior of the lateral malleolus - posterior of the lateral malleolus |
| Talocrural/ankle |
medial: medial of talocrural joint/deltoid (anterior tibiotalar, posterior tibiotalar, tibiocalcaneal, tibionavicular)
lateral: lateral collateral of ankle joint (anterior talofibular, posterior talofibular, calcaneofibular) |
| Foot - subtalar/talocalcaneal |
anterior/posterior - lateral/medial - interosseous |
| Foot - transverse tarsal |
Talocalcaneonavicular: dorsal talonavicular - plantar calcaneonavicular/spring - bifurcated (calcaneonavicular)
Calcaneocuboid: dorsal calcaneocuboid - long plantar - plantar calcaneocuboid - bifurcated (calcaneocuboid) |
| Foot - distal intertarsal |
Cuneonavicular: plantar - dorsal
Cuboideonavicular: plantar - dorsal
Intercuneiform: plantar - dorsal - interosseous |
| Foot - other |
Tarsometatarsal/Lisfranc: plantar - dorsal
Intermetatarsal/metatarsal: plantar - dorsal - interosseous - superficial transverse - deep transverse
Metatarsophalangeal: plantar - collateral
Interphalangeal: plantar - collateral |
| Arches of the foot |
Longitudinal - Transverse |
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