One of the greatest influences on my understanding of the geometry of the airways, and thereby the technical skills and processes required to place airway devices of all types, has been the work on publications of Dr Kenneth Greenland. Greenland’s publication in the BJA in 2010 should be required reading for anybody who performs intubation. However, if you want to really understand theories of the airway curves and columns, I highly recommend getting it from the horses mouth. Here below are several videos in which can Greenland explains his thinking and theories. While they are a little longer than your average #FOAM material, I cannot recommend them strongly enough.
https://www.youtube.com/watch?v=VAhmohUI9R8
https://www.youtube.com/watch?v=p2Xcm7csV5w