An ulcer is a hole in soft tissue. In the esophogus it usually caused by stomach acid working its way above the duodenal constriction especially due to laying down after a large meal.
Food is passed through the esophagus by using the process of peristalsis. Specifically, it connects the pharynx, which is the body cavity that is common to the digestive factory and respiratory system with the stomach, where the second stage of digestion is initiated.
The esophagus is a tube that connects your pharynx (tube that is posterior to the nasal cavity and mouth) down the stomach. Each time you swallow, the epiglottis covers your larynx (airway to your lung) to prevent food from going into the larynx and to ensure the food goes down your esophagus to the esophageal junction, where the food is deposited into your stomach for digestion. Peristalsis is the autonomic function in which the esophageal muscles push the food down the esophagus into the stomach.
There is a notch at the base of your throat. The doctors generally place an endotracheal (ET) tube through the skin and into the windpipe. This gives the upper end of the windpipe a chance to "rest" or be isolated and still the person will be able to receive air and breath through the ET tube. Hopefully the cancer will be conquered and the tube can be removed. He will have a scar at the base of his throat as a reminder, but there are generally no other problems associated with the ET tube.