accessorius 🔊 Listen to this < /ˌæk səˈsɔr iˌaɪ, -ˈsoʊr-/. Anatomy. any muscle, nerve, gland, etc., that reinforces the action of another. noun anatomy a muscle or nerve that has an augmenting action Nervus accessorius – Wikipedia Nervus accessorius – Wikipedia Accessory nerve – Wikipedia Share Facebook Twitter Google +