Synonyms: anal triangle non-striated muscle anal part of perineum smooth muscle anal region non-striated muscle anal part of perineum smooth muscle tissue anal triangle involuntary muscle non-striated muscle of anal triangle smooth muscle of anal region involuntary muscle of anal part of perineum smooth muscle of anal part of perineum anal region smooth muscle tissue smooth muscle tissue of anal triangle involuntary muscle of anal triangle anal region involuntary muscle involuntary muscle of anal region anal triangle smooth muscle tissue smooth muscle of anal triangle non-striated muscle of anal part of perineum smooth muscle tissue of anal part of perineum smooth muscle tissue of anal region anal part of perineum non-striated muscle non-striated muscle of anal region anal part of perineum involuntary muscle anal triangle smooth muscle