Well this is all kinds of messed up. http://www.cartoonbrew.com/business/john-textor-made-16-million-in-2011-while-digital-domains-revenue-dropped.html
There are 16-20 cartilagines tracheales. Cartilagines occupy 2/3 to 3/4 of the circumference of the trachea. (not 1/2) Anyway this is great thread. Good luck!