What is ligament?

A ligament is fibrous connective tissue that connect one bone to another adjacent bone. Basically, ligaments are made of collagen fibers which are strong, flexible, and resistant to damage from outside stresses like pulling or compressing. These collagen fibers lie in parallel, forming bundles with  multiplied strength. Those bundles of collagen are attached to the periosteum (the outer layer that covers the surface of all bones)

Composition of ligaments

The extracellular components of ligaments consist of:

  • Water
  • Type I collagen (70% of dry weight)
  • Elastin
  • lipids
  • Proteoglycans
  • Epiligament coat
    • Not all ligaments have epiligament coat
    • Analogous to epitenon of tendons

Cellular component of ligaments consist of:

  • The main cell type:  fibroblast
  • Low vascularity and cellularity

What do ligaments do?

Ligaments function to

  • Restrict joint motion
  • Stabilize joint
  • Help with joint proprioception (thanks to mechanoreceptors and free nerve endings that present in ligaments)

Ligaments act as chain links that attach bones to other bones. Ligaments allow individual bones in the links to move freely while keeping them remaining in sequence and not moving apart. In other words, ligaments function to allow for the joint’s movement while preventing the joint from dislocating.

Ligaments also prevent movement. For example, thanks to ligaments, our leg can’t bend backwards, or we can not bend our knee in the opposite direction.  By this, ligaments help stabilize the joint when it is in motion.

Ligaments harbor mechanoreceptors free nerve endings which asssist with perceptions of joint movement or joint sense. Thanks to this, we know the positions of our limbs in space and to detect and assess the magnitudes of movements and forces without vision.

Ligament vs tendon

A ligament and a tendon are all fibrous connective tissues. However, while a ligament connects bones to bones, a tendon attaches muscle to bone or muscles to structures. If a ligament serves to hold  structures together and keep them stable, a tendon, on the other hand, serves to move the bone or structure.

When compared to a tendon, a ligament has:

  • Lower percentage of collagen
  • Higher percentage of proteoglycans and water
  • Less organized collagen fibers
  • Rounder fibroblasts

Common ligament injuries and disorders

Below are somecommon injuries or disorders that involve the ligaments.

Torn ACL (Torn anterior cruciate ligament)

This is among the leading ligament injuries in the knee in which the anterior cruciate ligament is torn.  ACL plays a role of as a stabilizer of the knee, preventing the tibia from sliding forward, thus, torn ACL leads to instability.

TMJ Disorder

TMJ disorder refers to the temporomandibular disorder marked by pain in the jaw joint and the muscles controlling jaw movement. People with TMJD usually experience pain and movement restriction of in their jaw joint.

Sprained ankle

A sprained ankle is one of the most common injury that people happen to get. This condition occurs when one or several ligaments on the outer side of the ankle get stretched or torn. Symptoms are swollen ankle, pain, and the difficulty movement.

Plantar Fasciitis

Plantar fasciitis is a condition in which the plantar fascia experience pain and inflammation due to micro-tears in the ligament. Plantar fascia is the thick, strong band of connective tissue stretched along the bottom of the foot, connecting the calcaneus to the toes.

Shoulder Separation

This condition is also known as acromioclavicular or AC separation. It is caused by when the ligaments that connect the scapula to the clavicle are torn.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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