Are мускул and мышца synonymous?

Question

Are мускул and мышца synonymous?

Answer 1

Non-interchangeable use of мышца/ы in (about) medical situations with verbs:
болеть – to ache, мышцы болели (after training)
сводить – to get cramp, свело мышцу [судорогой]
потянуть – to pull/strain, потянул мышцу
порвать – to tear, порвал мышцу

Other:
мышечная масса – muscle(s) mass

Non-interchangeable use of мускул with verbs:
дрогнуть – to move/jerk, ни один мускул не дрогнул на его лице – his face stayed still, without moving a muscle

I don’t think it’s practical to learn cases when the two words are interchangeable but maybe have some secondary and tertiary shades of difference. I’m sure it’s a matter of serious linguistic research, evidently not done. Unconscious remembering of use cases can be of more help.

Nevertheless: one more guess about trends of мышца / мускул usage.
  мышца appears to be a base word of traditional medical/anatomical terminology about muscles,
  мускул seems to be a newer word which is more active in contexts/styles perceived as more modern and progressive, e. g. concerning ‘культура тела’ which is not limited to body-building. (These contexts arose in Russia a century ago, I suppose.)
In Russia, if I’m not mistaken, a physical force was traditionally attributed to sinews, not to muscles. I think that for some time мускул was used to reflect new (not of 'common' people of the past) views about it and marked the adeptness to 'new world' of reason and so on (I perceive it so in some texts).
Мышца is 'deeper' Russian than мускул, a child probably first learns a word мышца, then – мускул (true for me).
Making the difference farcical: a simple country guy has мышцы, a towny builds мускулы.

Answer 2

Yes they are.

Мышца is a CS calque of Latin musculus "little mouse". They can be used interchangeably in Russian.

Some derived terms like внутримышечно "intramuscularly" or мускулистый "muscular, having big muscles" use only one of the roots, though.

Also, мышца is used in established compound names of separate muscles: широчайшая мышца спины "lat", икроножные мышцы "calves" etc. In non idiomatic descriptions like мышцы пресса "abs" мускул can be used as well.

Answer 3

These words are often interchangeable. But in general the difference is like this:

• мышцы is what everyone has from birth, biologically. If you go to Wiki, you can see that all 640 muscles are called мышцы, because it's the preferred word for tiny muscles unlike biceps e.g. When we say мышцы we often mean flesh.
• мускулы is associated with physical power often acquired through training. Biceps, triceps, but not abs! Abs are called: мышцы пресса, мышцы живота (although Google found ~4K matches for мускулы пресса, but check out 386К for мышцы пресса). So another criterium: мускул is a muscle which is visibly big/long and expands/contracts by a wide amplitude.

Answer 4

Мышца is what we have inside. Мускул is what we see or show out. But in 90% cases they are interchangeable.

Answer 5

No.
Compare: мускул / мышца

мускул is geometric in form, the external form of things, has no internal structure, while мышца has their essence.

UPDATE:

It would be the same, as to suppose that pairs eggshell / egg, sphere / ball are synonyms.

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