sphincter
n. Ring of muscle surrounding and closing an opening in the body. [greek sphiggo bind tight]
n. A muscle which surrounds, and by its contraction tends to close, a natural opening; as, the sphincter of the bladder.
n. Ring of muscle surrounding and closing an opening in the body. [greek sphiggo bind tight]
n. A muscle which surrounds, and by its contraction tends to close, a natural opening; as, the sphincter of the bladder.