- smooth muscle, involuntary muscle - a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart)
--1 is a kind of muscle, musculus
--1 has particulars: myometrium; musculus sphincter ani internus - smooth muscle - muscle tissue that does not appear striated under the microscope; has the form of thin layers or sheets
--2 is a kind of muscle, muscular tissue
--2 has part: smooth muscle cell