A prepositional phrase is comprised of two parts, a preposition and an object of the preposition. Together, they form the prepositional phrase that is then inserted in a sentence to modify some noun or verb.
The epiglottis is a flap made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. It stands open during breathing, allowing air into the larynx.
URL of this page: //medlineplus.gov/ency/article/000605.htm. Epiglottitis is inflammation of the epiglottis. This is the tissue that covers the trachea (windpipe). Epiglottitis is a life-threatening disease. The epiglottis is a stiff, yet flexible tissue (called cartilage) at the back of the tongue. It closes your windpipe (trachea) when you swallow so food does not enter your airway. This helps prevent coughing or choking after swallowing.