The cricoid cartilage /ˌkraɪkɔɪd ˈkɑːrtɪlɪdʒ/, or simply cricoid (from the Greek krikoeides meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage around the trachea. It forms the back part of the voice box and functions as an attachment site for muscles, cartilages, and ligaments involved in opening and closing the airway and in producing speech.