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
History of beliefs about the human body these views, that the soul has aspects that can't be felt by normal methods, and physical manifestations that can be felt. "For even if one and being are spoken of in several ways, what is properly so spoken of is the actuality" -Aristotle in DeAnima Aristotle forms the idea of Hylomorphism, that the soul and the body are not capable of being split apart without destroying both in the process. Despite this idea of the body and the soul Aristotle viewed disorder in what could be seen and felt. He was a proponent of the humoral theory that classified disorder