Correct spelling for the English word "musculars" is [mˈʌskjʊləz], [mˈʌskjʊləz], [m_ˈʌ_s_k_j_ʊ_l_ə_z] (IPA phonetic alphabet).
The word "musculars" does not have an established etymology as it is not a commonly used English word. The term "muscular" however, which relates to muscles or strength, comes from the Latin word "musculus", meaning "little mouse". This term was used metaphorically to refer to small body parts resembling mice in shape. Over time, the meaning evolved to denote muscles, which were thought to be small and rodent-like in appearance.