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
Catholic theology of the body creation of God. God created the body like a work of art in his image. This creation reflects God’s intelligence. The human body is (eikon) somehow similar to God. To be completed as a mirror of him, is the task for every Christian. Unlike the human body, the soul is an image of God. The body cannot be an image of God, otherwise God would look like a human being with a human body. Only the soul can see God, but it is caught between the flesh and spirit. It constantly has to make a choice between the two. Origen