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 manuscript is recorded in the Yellow Emperors Inner Cannon, and it being recorded in this way represents the attention to the individuals perspective in creating therapies like acupuncture to treat body ailments. The Inner Cannon was revised by natural Philosophers of the time and the approved version of the Han Court and became a foundational text for the ideals and perceptions of the human body. It focused on Qi, Yin and Yang balance, and Five phase theory to explain health can disease. Referred to as the life force of the body, or the means by which the body is able