Tissue Mechanics: Ligament/Tendon Flashcards Preview

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Flashcards in Tissue Mechanics: Ligament/Tendon Deck (31)
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1
Q

What is responsible for transmitting tensile forces?

A

tendon

2
Q

what is responsible for limiting joint motion?

A

ligament

3
Q

what is the difference in composition between tendon and ligament?

A

tendon has less elastin and less proteoglycans- so it will be less stretchy and attract less water

4
Q

describe the organization of collagen fibrils in tendons.

A

collagenous fibers are parallel to each other and interconnected –> makes them very strong

5
Q

Where are tendon synovial sheaths commonly found?

A

in the tendons of hands and feet

*is a closed duct around tendons gliding on bone surfaces

6
Q

synovial sheaths have two layers- inner (visceral) and outer (parietal) sheets. which layer has the synovial cells?

A

outer (parietal) sheet

7
Q

what is a paratenon?

A

those tendons that do not have a synovial sheath (Ex. achilles tendon) may have a paratenon to reduce friction

8
Q

which sheet in a paretnon has synovial cells?

A

inner surface

9
Q

what is an epitenon?

A

located under the paratenon and surrounds the tendon

10
Q

describe the organization of collagen fibers in the epitenon.

A

fibers are NOT parallel to each other; the strands run obliquely, longitudinal, or transverse to the long axis of the tendon

11
Q

after stretching, what happens to the angle of epitenon fibers at the tenon axis?

A

angle decreases (from 60 to 30 degrees)

12
Q

what is endotenon?

A

envelopes the primary, secondary, and tertiary fiber bundles together; allows fiber bundles to glide with respect to each other

13
Q

which tendinous structure carries blood flow, nerves, and lymph to the tendon?

A

endotenon

14
Q

what is the crimping of tendons due to?

A

cross-linking of proteoglycans

15
Q

what is the tensile strength of tendons due to?

A

collagen

16
Q

are tendons extensible or inextensible?

A

inextensible- tendons provide efficient transmission from muscle to bone (that is, they are NOT very elastic)

17
Q

do tendons have resistance against shear and compressive forces?

A

not really

18
Q

what are the disadvantages if tendon elasticity increases (reduced stiffness)?

A

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

19
Q

what is the effect of increasing cross-sectional area on stress vs. strain curve for tendons?

A

the greater the cross-sectional area:

  • the greater the stiffness
  • the greater the max. stress
  • but the SAME STRAIN
20
Q

at what percentage of strain does the tendon enter failure region?

A

4% or more

21
Q

what is the effect of creep on tendons?

A

in an isotonic contraction, the tendon will lengthen slightly and more muscle fibers will be recruited in order to maintain the position of the limb

22
Q

what is teh effect of stress-relaxation on tendons?

A

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

23
Q

what is teh effect of increasing rate of load onto a tendon?

A

the faster you load a tendon, the more stress and stiff the tendon becomes

24
Q

what is the order in which the muscuolotendinous unit will disrupt?

A
  1. myotendinous junction
  2. osteotendinous junction
  3. muscle belly
  4. tendon
25
Q

when is tendon at risk of rupture?

A
  • tension applied quickly
  • tension applied obliquely
  • tendon is preloaded before injurious load
26
Q

at a high loading rate, where will the point of failure be in a ligament?

A

mid-subtance area (at the tendon)

27
Q

at a low loading rate, where will the point of failure be in a ligament?

A

bony insertion

28
Q

up to 20 y/o, what properties are seen in tendons/ligaments?- in terms of # of crosslinks, toe region, collagen diameter, and tensile strength?

A
  • increased cross-links
  • decrease in toe region
  • increased collagen diameter (collagen density)
  • increased tensile strength during maturation
29
Q

what happens to properties of tendons/ligaments after 20y/o?

A
  • decreased collagen diameter

- decreased stiffness and tensile strength

30
Q

how does YOung’s modulus for tendons compare in men vs. women?

A

tendon stiffness and Young’s modulus are LOWER in women than men

31
Q

what happens to tendons/ligaments after a period of immobilization?

A

results in weaker tissue, less stiff that undergoes larger elongation for the same load (can get reinjured easily)