The cartilage at the tip of my nose is split in the middle and separates since I was born.

Thank you for your question.  What it sounds like what you have is a bifid tip that is due to the ligaments between the two cartilages in the tip of  the nose (lower lateral cartilages) being overly developed and pushing the tip defining points outward.  You have to be careful with the approach as over-resection and overly tightening the tip can alter the appearance of the nose dramatically.

Make sure you consult with a double board certified facial plastic and reconstructive surgeon.

What you are describing is a bifid nasal tip.  There are actually two separate cartilages here and it sounds as though yours are more separated than they should be.  This is usually very easy to correct with a tip rhinoplasty using sutures to align the cartilages and occasionally a cartilage graft to provide additional tip support.  

Yes, this is quite common.  It is relatively easy to correct in that the paired lower lateral cartilages need to be sutured together to eliminate it.  A tip rhinoplasty will achieve this. 

Is the "split" in the middle of the cartilages because we see the two cartilages separately, with a space between the cartilages, like in the woman pictured just above?

I usually make computer morphs when I'm answering questions like this, to show the changes that are possible with a rhinoplasty. For example see this page:FacialSurgery.com/RealSelf/RealSelf_Morphs.html... but of course you didn't post photos. If you go to the "Web reference" link just below my post, at the *very* bottom of that page is a link to instructions on taking and sending photos that are most useful for an online consultation like this, in case you'd like a more complete evaluation.

Thank you for your question! It sounds like what you are describing is a nasal tip cleft from poorly defined lower lateral cartilages.  We'd have to see them and get a better look at what you are describing to give you a better assessment.  In regards to the position of the cartilages and them being split - the tip defining cartilages are similar to the M on the McDonald's logo.  The problem comes in when there are discrepancies in the width, the strength and rigidity, the length, etc.  In order to address these issues you permanently you would need to be evaluated for a rhinoplasty or tip rhinoplasty.  Sometimes these can be addressed non-surgically with fillers.  That being said, non-surgical solutions are also non-permanent.  I hope some of this helps! Best of luck.

The exact name is not  as important as understanding why there is a linear indentation at the tip of the nose.  The indentation is simply a gap between the right and left alar cartilages as they meet (or barely) meet at the center of the tip of the nose.  An open rhinoplasty which allows exposure of the alar cartilages allows for surgical changes to be made and sutures to be used to approximately the two cartilages such that there is no longer a gap.  Look for a Board Certified Plastic Surgeon who is capable of open rhinoplasty technique.  Best Wishes. Dr. Louise Ferland Richmond, VA