What causes a nosebleed?

How are the delicate blood vessels in your nose responsible for these unpleasant incidents?

Most of us are familiar with the unpleasant sensation of a nosebleed. They are common because there are so many blood vessels in your nose, and it doesn’t take a lot of trauma for them to burst. They can start from one of two places – inside your nostrils (anterior) or at the back of your nose (posterior). Anterior nosebleeds can be caused by a minor injury to the nose, high altitude or allergies. However, posterior nosebleeds start from ruptured arteries supplying blood to the space between the roof of your mouth and your brain. These more serious bleeds are less common and are caused by head injuries or a broken nose, among others.

The anatomy of a nosebleed

A nosebleed will stem from one of two locations

Image credit: Future PLC. Illustration by The Art Agency / Barry Croucher

This article was originally published in How It Works issue 108, written by Charlie Evans 

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