Tendons and ligaments

Low intrinsic healing capacity

What is the healing capacity of cartilage

Low intrinsic healing capacity

What is the healing capacity of tendons/ligaments

Muscle to bone

Tendons connect...

Tendons

Connect muscle to bone

Bone to bone

Ligaments connect...

Ligaments

Connect bone to bone

Positional

Energy storing

What are the 2 functional classifications of tendons/ligaments

Positional tendons

Tendons that are low strain and keep things in place

Low strain (low elasticity)

Keep things in place

Extensor tendons

What are positional tendons

Energy storing tendons

Load bearing tendons with high strain and elasticity

High strain (high elasticity)

Load-bearing

Flexor tendons

What are energy storing tendons

Collagen fibril

Collection of fibrils-> collagen fiber

Endotenon wraps around fibers forming a fascicle

Interfascicular matrix lies between fascicles

Epitenon wraps the fascicles together

Paratenon surrounds the entire tendon

What is the hierarchal structure of a tendon

Type I collagen

Col III, COMP, decorin

What are the components of the fascicular matrix

Endotenon

The interfascicular matrix is also called...

Elastin

Lubricin

Lower levels of collagen (type I)

What are the components of the interfascicular matrix

Fascicles slide against each other to allow for tendon elongation

What is interfascicle sliding

Collagen fibers in a relaxed tendon have a crimped pattern that flattens to allow elongation

What is collagen fiber crimp

Toe region

Elastic region

Plastic region

Failure point

What are the levels of tendon strain and stress

Toe region

Low stress and low strain of a tendon

Low stress

Low strain

Mostly relaxed tendon

What is the toe region

Elastic region

Area of lower strain and increasing stress where the tendon fibers flatten out

Area of lower strain and increasing stress where the tendon fibers flatten out

What is the elastic region

Plastic region

Area of increasing tendon strain while at consistent high stress that results in microscopic tearing in the tendon when it cannot flatten further

Area of increasing tendon strain while at consistent high stress that results in microscopic tearing in the tendon when it cannot flatten further

What is the plastic region

Failure point

Point of high stress and high strain where a tendon will snap

Point of high stress and high strain where a tendon will snap

What is the failure point

Tenocytes

Cells of tendons

Relatively acellular and avascular in comparison to the amount of fibers

What is the cellularity and vascularization of tendons

Tenocytes synthesize collagen molecules and secrete them extracellularly

Collagen assembly and hierarchal arrangement occurs extracellularly

How is matrix formed

Amino acids join to form an a-chain

3 a-chains coil to form triple helix-> collagen molecule

Link to form tropocollagen (microfibril)

Microfibrils join to make collagen fiber

What is the process of collagen assembly