What causes the lump?

What causes the lump in your throat when your about to cry??

• Just out of interest, what exactly is or causes the 'lump' you get in your throat when your about to cry?? If you leave it long enough when your really upset by something and you try and hold it in, it becomes quite large and even painful, but then goes when you start blubbing!! Its quite baffling really and i was just wondering if anyone knew the actual physics or biological reason or cause for it :-}

• Answer:

  An important part of opening the throat to allow the lungs to get more air involves expanding the glottis - the muscle which controls the opening from the back of the throat (pharynx) into the voice box (larynx) - so that more air can pass through it. So part of the autonomic response of crying is to use throat muscles to open the glottis as wide as possible. This doesn't pose a problem until you want to swallow; swallowing involves closing the glottis, so that food doesn't get into your larynx. So if you try to swallow while you are crying, the muscles for swallowing are fighting against the muscles for crying, and this tug-of-war over the glottis is perceived as a lump behind your larynx which makes it difficult to swallow.