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 the senses to identify what has gone wrong. The Ebers Papyrus refers to many god-like and spiritual infestations of the body that could not be explained at the time. Despite the explanations for maladies by spiritual rational, the interventions described to investigate and see the body were distinctly disconnected for the spirit or life force of the body and was principally about what could be seen or touched. Descriptions of the exact placement of the heart within the body, the circulation of blood are in no doubt accurate as Egyptians practiced embalming their dead by removal of organs and placement