Trachea are generally highly elastic but they may calcify with age. The trachealis muscle connects the ends of the incomplete rings and contracts during coughing, reducing the size of the lumen of the trachea to increase the rate of air flow. The esophagus lies posteriorly to the trachea, adjoining along the tracheoesophageal stripe. Circular horizontal bands of fibrous tissue called the annular ligaments of trachea join the tracheal rings together. The cartilaginous rings are incomplete to allow the trachea to collapse slightly so that food can pass down the esophagus. A flap-like epiglottis closes the opening to the larynx during swallowing
Explorers of the Human Body new educational program, introducing the audience to the human body. Shin Dong-yup was chosen to be the lead MC, with the Super Junior members being regulars and co-MCs of the program. Ratings for the show became the highest of all three shows that aired in SBS's new "Good Sunday" lineup as the show is educational and entertaining to watch. It was also the first and currently the only variety show that included every member of Super Junior as regulars. Each episode has a main topic to explore regarding the human body. In the first episode, which involved the tongue and