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
The Human Body (TV series) July 2001 and includes a 50-minute feature on "The Making of the Human Body" - A final overview that reveals the techniques and developments that made the series possible. The series was adapted into a film released for IMAX cinemas. The film won the Giant Screen Theatre Association's Best Film For Lifelong Learning award. The book accompanying the series was written by Anthony Smith. According to one review, "Smith transcends anatomical trivia to record our bodies' powerful tale with empathy and clarity." The Human Body (TV series) The Human Body is a seven-part documentary series, first shown on 20 May