Which of the following does NOT cause a normal constriction of the oesophagus?Group of answer choicesLeft main bronchusAortic archDiaphragmRight atrium

The right atrium does NOT cause a normal constriction of the oesophagus.

Here's why:

1. The oesophagus is a muscular tube that connects the throat to the stomach. It passes down the neck, through the chest, and into the abdomen.

2. The oesophagus has several points where it naturally narrows or constricts. These are caused by structures that are close to the oesophagus.

3. The left main bronchus, aortic arch, and diaphragm are all structures that are in close proximity to the oesophagus and can cause it to constrict.

4. The left main bronchus crosses the oesophagus causing a constriction. The aortic arch also causes a constriction as it passes over the oesophagus. The diaphragm, where the oesophagus passes into the stomach, is another point of constriction