Muscular rhymes with:
cardiovascular, gastrovascular, vascular, avuncular, binocular, cardiovascular, circular, curricular, extracurricular, gastrovascular, intermolecular, jocular, molecular, particular, perpendicular, secular, semicircular, spectacular, testicular, unspectacular, vascular, vehicular, vernacular
Muscular sounds like:
mackellar, mackler, mankiller, mcaleer, mcclary, mccleary, mccleery, mcclory, mccluer, mcclure, mccullar, mcculler, mcelroy, mcglory, mcilroy, mckellar, mckeller, mclaury, mclear, mcleary, mcleroy, mclure, mechler, meckler, meisler, mescalero, mesler, messler, michler, mickler, migliore, minckler, minkler, mischler, mishler, missler, mockler, mononuclear, mosler, muckleroy