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
Theology of the Body nature of human beings in relation to God. The "Theology of the Body" presents an interpretation of the fundamental significance of the body, and in particular of sexual differentiation and complementarity, one which aims to challenge common contemporary philosophical views. Nevertheless, the pope's personalistic phenomenology is "echoing what he learned from St. John of the Cross" and is "in harmony with St. Thomas Aquinas". Francis Bacon was an early empiricist who focused on problems of knowledge. In his Great Instauration, he argued that the current state of knowledge is immature and not advancing. His purpose was for the human mind