Why are the rings of cartilage surrounding the trachea c-shaped? why are the rings of cartilage surrounding the trachea c-shaped? the c rings of cartilage allow the trachea to change diameter during breathing. the c rings of cartilage keep the trachea patent (open). the c rings of cartilage allow the esophagus to expand during swallowing, allow the trachea to change diameter during breathing, and keep the trachea patent (open). the c rings of cartilage allow the esophagus to expand during swallowing?