is a depression
Opening
A meatus is an opening; therefor, it's a depression, not a projection.
projection
projection
projection
projection
projection
....opening?
Ramus.
"A crest is a projection or ridge, especially of bone; cresta"source: chacha.com
The plural of meatus is meatuses or meatus - both forms are accepted.
projection. The bumps of bone around your knees and elbows are almost all called condyles.
The external auditory meatus and the external acoustic meatus are two names for the same structure.