Tendon/Ligament

Question 1

Basic Structure of a tendon

Answer 1

Transmits tensile force created in the muscle to the bone
Composed of collagen and elastin embedded in a matrix of proteo and water
Synthesized by tenocytes and tenoblasts
Each muscle has proximal and distal tendon

Question 2

Tendon

Answer 2

muscle to bone

Transmit tensile forces

Question 3

Ligament

Answer 3

bone to bone

Limits bone motion

Question 4

Micro-architecture of tendon

Answer 4

microfibril - subfibril - fibril - fascicle - tendon

Bundled structure is good because harder to damage

Question 5

Tendons withstand

Answer 5

unidirectional loads

fibers go along the tendon - parallel

Question 6

Ligaments resist

Answer 6

tensile stress in one direction and smaller stresses in other directions
Fibers are not all parallel - kind of wavy

Question 7

Tendon synovial sheaths

Answer 7

Closed duct around tendons gliding on bone surfaces
Frequently observed in tendons of hand and feet
The sheath is formed of two membranes: inner (visceral) and outer (parietal) sheets

Question 8

Function of tendon

Answer 8

transmit force across a joint without obstructing the ROM that the joint allows

Question 9

Tendon sheath function

Answer 9

parietal sheath has synovial cells
Space btw parietal and visceral membrane is filled with synovial fluid
- facilitates movement and gliding
Pulley - hold tendon close to bone

Question 10

Paratendon

Answer 10

Tendons that dont have a synovial sheath may have paratendon to reduce friction
Composed of loose fibrilar tissue (I and III collagen)
Functions as elastic sleve that permits free movement of tendon against surrounding tissue
Inner surface has synoovial cells
Does not experience much load

Question 11

Epitendon

Answer 11

Located under the paratendon and surroungs the tendon
Fibrilar network of collagen with strands of 10 nm thickness
Strands run oblique, long, or trans to the long axis of the tendon
Will experience tension when tendon is loaded

Question 12

Endotendon

Answer 12

thin network of crisscross fibrils
Envelops the pramary secondary and tertiary fiber bundles together
proteo are present btw endo and tendon fibers - hydration
Allows fiber bundles to glide
Carry BVs, nerves and lymph to tendons
gives you fascicles and smooth for friction? carry load

Question 13

Crimpng of tendons

Answer 13

A wavy formation within fascicles
Varies and irregular along fibers
Believed to result from cross linking of proteo
Disappears when stretched and reappears when unloaded
Removal of crimp dominates low strain range

Question 14

Biomechanical charactersitics of tendons

Answer 14

Tenssile strength: due to molecular organization
Adequate flex: elastin fibers
Inextensibility: efficient transmission of force from muscles to bones
Inderior resistnace against shear and compressive forces

Question 15

What disadvantages if tendon elasticity increasaes?

Answer 15

A muscle will have to exert a greater force to move bone the same distance as more stretch will be induced in the tendon before movement occurs

Question 16

Effect of inc tissue CSA on stress - strain

Answer 16

Greater CSA
the greater the stiffness
The greater the max stress
The more energy it will need before it breaks

Question 17

Effect of inc tissue length on stress - strain

Answer 17

The less stiffness
the greater the elongation
If length doubles - stiffness is in half
If longer - more deformation before it ruptures

Question 18

Secondary biomechanical functions of tendons

Answer 18

Eliminate unecessary length of muscle: enables muscle belly at a distance from the joint
Absorb shock: limits damage to muscles

Question 19

Toe region

Answer 19

Changes are at light microscopic level
Waviness of fiber nundles straightened out
Continued elongation results in increasesd stiffness
End of toe region ranges from 1.5-4%

Question 20

Linear Region

Answer 20

Range 2-4%
Tendon will recover to its original length if not srained beyond linear region
Few minor strands regain waviness towards the end indicating early ruptures of a few bundles
Stratching occurs on the fibrilar and molecular heirarcy (smallest to largest)

Question 21

Falure region

Answer 21

Collagen fibers slide past each other
Possibe rupture of cross links
Reduction in stiffness
Waviness reappears at an inc rate indicating gradual rupturing of bundles
Ruptured fibers/bundles recoil

Question 22

In vitro tensile strength

Answer 22

50-100

Question 23

A tendon with 1cm area can carry

Answer 23

0.5-1 ton 1000kg

Question 24

Tensile strength of a tendon is about ___ the strength of the muscle it is attached to

Answer 24

twice

Muscle gets damaged before the tendon

Question 25

Tendon compliance of junctions Aponeurosis Bone tendon junction tendon junction

Answer 25

Aponeurosis is most compliant Bone tendon junction more compliant than tendon Tendon = stiffest Takes mores energy for aponeurosis to break than the tendon - aponeurosis has more toughness

Question 26

What is the effect of creep of tendon

Answer 26

Effect will creep on tendons - an isotonic tendon will lengthen slightly and more muscle fibers will be recruited in order to maintain postiion of the limb

Question 27

Creep

Answer 27

Constant load isotonic tendon/ligament will keep elongating (engaging) overtime

Question 28

Stress relaxation

Answer 28

Isometric The length is maintained constant Load becomes less and less

Question 29

What is effect of and stress relaxation of tendon

Answer 29

an isometric contraction, the stress in the tendon will decrease with time

Question 30

Loading and unloading - changes property of material?

Answer 30

Yes Response of tissue becomes more repeatable Subsequent use of same deformation results in less load Tissue stabilizaes after a period of time Chances of tissue getting damaged without warm up is much higher

Question 31

Musculotendinous Unit

Answer 31

Tendons func as unit of a muscle-tendon bone system A healthy tendon is seldom the weakest link of a system During testing of the unit disruption may occur - even partial transection - myotendinous junction - osteo tendinous junction - muscle belly - tendon Usually damage occurs in that order

Question 32

Tendon is under risk when...

Answer 32

Tension is applied quickly Tension is applied obliquely Tendon is preloaded before injurious load (expecting the step)

Question 33

Ligament - point of failure with high loading rate vs low loading rate

Answer 33

``` High = midsubstabce Low = bone insertion ```

Question 34

The physical properties of the tendon and ligament tissues depends on

Answer 34

and quality of cross-links within and btw the collagen molecules

Question 35

Aging effects up to 20 years old

Answer 35

Inc in cross links Dec inc rimping Inc in collagen diameter Overall increase in tensile strength during maturation

Question 36

Aging effects after 20 years old

Answer 36

Dec collagen diameter | Overall dec in stiffness and tensile strength

Question 37

Gender differences in biomechanical prop

Answer 37

the tendon stiffness and young's modulus are sig lower in women than in men

Question 38

Immobilization results in...

Answer 38

waker tissue, less stiff that undergoes elongation for the same load Cant jump back in after being immobilized - need to gradually build up