projection
projection
A meatus is an opening; therefor, it's a depression, not a projection.
projection
projection
is a depression
....opening?
A fissure is an opening or crack in the Earth's crust, typically where tectonic plates meet. It is not a projection or depression, but rather a narrow, long fracture in the ground.
"A crest is a projection or ridge, especially of bone; cresta"source: chacha.com
projection. The bumps of bone around your knees and elbows are almost all called condyles.
maniac is a serious type of depression the other is voices inside your head
The routine projection of the elbow that best demonstrates the radial head and tuberosity free of superimposition is the axial or "Coyle" method. This projection is performed with the patient's arm in a specific position, usually with the elbow flexed at 90 degrees and the forearm supinated or with the arm extended and the hand in a pronated position. This technique provides a clear view of the radial head while minimizing overlap from the ulna.
I think you are referring to a method of locating a nut in a piece of sheet metal. A rivet head nut is a nut with has a small projection not much thicker than the sheet metal to which you intend to fit it. This projection fits through a pre made hole in the sheet metal, and the small projection is peened over (deformed by hammering) to fix the nut to the sheet.