The correct spelling of myotasis is actually myotasis, with the stress on the second syllable (my-OH-ta-sis). The word, used in medical contexts, refers to the gradual decrease in muscle tone due to a neurological disorder. The pronunciation of this word is clear once you know the rules of pronunciation in English, and it can be spelled out phonetically as /ˌmaɪ.oʊˈteɪ.sɪs/ (MY-oh-TAY-sis). It's always important to double-check the spelling of any technical term to avoid any misunderstandings or errors.
Stretching of a muscle.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.