The Larynx (not to be pronounced "Larnyx") is a valve system at the top of the Trachea to keep food out.
The cricoid cartilage is like the final ring of the Trachea, only somewhat more complex. The Thyroid cartilage is shaped like a shield attached to but placed in front of the cricoid cartilage. This is what people are seeing when they observe the "Adam's Apple."
This structure is commonly called the voice box, but more correctly it should be labeled the "Larynx." Caution, do not call it the "larnyx!" This can cause a major stroke in some speech professors.