Sarah,
The columella is made up of what is called the medial crural footplates. These are part of the cartilage that makes up the tip of the nose and is intimately involved in all aspects of tip rotation and projection as well as the amount of nostril show. The part you are referring to hanging. The columella as well as the nasal tip dimensions can all be precisely controlled in rhinoplasty by placing grafts onto the nasal septum and suturing the medial crura to this graft in what is referred to as a tongue and groove fashion. We routinely use this type of maneuver in primary and revision rhinoplasty to achieve the appropriate tip dimensions. Please take some time to review our rhinoplasty photo gallery. I think you will get a good feel for what words have a hard time expressing. Please feel free to call with any further questions.
Ed Buckingham