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This animation will show how a hiatus hernia forms.
There are two types of hiatus hernia:
sliding and rolling.
This animation focuses on the more common type,
a sliding hiatus hernia.
Click the navigation arrows below the animation screen to play, pause, rewind
or fast-forward the animation. This animation contains sound.
Your oesophagus (the pipe that goes from your mouth to your stomach)
passes into your stomach through a hole (hiatus) in your diaphragm.
Normally, the stomach is situated completely below the diaphragm, as shown here.
The oesophageal sphincter acts like a one-way valve
to stop the acid that's produced in your stomach to break down food
from flowing up into your oesophagus.
Here we show the valve opening and closing.
In a sliding hiatus hernia,
the sphincter and the top part of the stomach push upwards into the chest.
A hiatus hernia can prevent the oesophageal sphincter from closing properly.
If this happens
acid from the stomach can pass into the oesophagus
and cause discomfort known as heartburn.
However, often hiatus hernias don't cause any symptoms.
Sliding hiatus hernias are usually quite small. They can slide
back and forth through the hiatus, so symptoms can come and go.
Sometimes, sliding and rolling hiatus hernias are present at the same time.
This is known as a mixed hernia.
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