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I have read the following {1}:

According to their envelope, tendons can be divided into tendons within a synovial sheath (i.e., sheathed tendons) and paratenon-covered tendons.

This means that all tendons have either a synovial sheath (a.k.a. true sheath) or a paratenon (a.k.a. false sheath). However, {2} seems to say that true (synovial) sheaths isn't that common:

However, not all tendons possess true synovial sheaths; these are in fact found only in areas where a sudden change in direction and an increase in friction require very efficient lubrication.

and {3} seems to say that false (paratenon) sheaths isn't that common either:

In addition, some tendons have a ‘paratenon’ that is separate from the tendon itself, but nevertheless surrounds it. It is also known as a false tendon sheath and the best example is that around the Achilles tendon.

This confuses me. Do all tendons have either a synovial sheath (a.k.a. true sheath) or a paratenon (a.k.a. false sheath)?

Synovial sheath (image source):

enter image description here

Paratenon (mirror):

enter image description here


References:

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