Attached Link: http://www.facialsurgery.com/INTRAOP1.HTM

The shape of the long part of the nose is determined by two structures: The small, thin bones at the top and the pair of cartilaginous structures below it which also determine the shape of the top. The 'hook' in a nose is the place where the bones end and the cartilage begins (not to be confused with Poser's NoseBump dial), visibly. I say 'visibly' because most peoples' noses have a fairly smooth transition from the bones to the cartilage. I used to think it was one piece of cartilage until I visited the site linked here -- now I understand "2-bulb" nose tips like Cybill Shepherd's and Karl Malden's a lot better.