Tissue Mechanics: Ligament/Tendon Flashcards
What is responsible for transmitting tensile forces?
tendon
what is responsible for limiting joint motion?
ligament
what is the difference in composition between tendon and ligament?
tendon has less elastin and less proteoglycans- so it will be less stretchy and attract less water
describe the organization of collagen fibrils in tendons.
collagenous fibers are parallel to each other and interconnected –> makes them very strong
Where are tendon synovial sheaths commonly found?
in the tendons of hands and feet
*is a closed duct around tendons gliding on bone surfaces
synovial sheaths have two layers- inner (visceral) and outer (parietal) sheets. which layer has the synovial cells?
outer (parietal) sheet
what is a paratenon?
those tendons that do not have a synovial sheath (Ex. achilles tendon) may have a paratenon to reduce friction
which sheet in a paretnon has synovial cells?
inner surface
what is an epitenon?
located under the paratenon and surrounds the tendon
describe the organization of collagen fibers in the epitenon.
fibers are NOT parallel to each other; the strands run obliquely, longitudinal, or transverse to the long axis of the tendon
after stretching, what happens to the angle of epitenon fibers at the tenon axis?
angle decreases (from 60 to 30 degrees)
what is endotenon?
envelopes the primary, secondary, and tertiary fiber bundles together; allows fiber bundles to glide with respect to each other
which tendinous structure carries blood flow, nerves, and lymph to the tendon?
endotenon
what is the crimping of tendons due to?
cross-linking of proteoglycans
what is the tensile strength of tendons due to?
collagen
are tendons extensible or inextensible?
inextensible- tendons provide efficient transmission from muscle to bone (that is, they are NOT very elastic)
do tendons have resistance against shear and compressive forces?
not really
what are the disadvantages if tendon elasticity increases (reduced stiffness)?
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
what is the effect of increasing cross-sectional area on stress vs. strain curve for tendons?
the greater the cross-sectional area:
- the greater the stiffness
- the greater the max. stress
- but the SAME STRAIN
at what percentage of strain does the tendon enter failure region?
4% or more
what is the effect of creep on tendons?
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
what is teh effect of stress-relaxation on tendons?
in an isometric contraction, the stress in teh tendon will decrease with time
what is teh effect of increasing rate of load onto a tendon?
the faster you load a tendon, the more stress and stiff the tendon becomes
what is the order in which the muscuolotendinous unit will disrupt?
- myotendinous junction
- osteotendinous junction
- muscle belly
- tendon
