The following clip shows what happens during a normal swallow and for someone with abnormal swallow after a stroke. This is known as Dysphagia It is essential to follow any eating guidelines if the swallow is unsafe to prevent risk of food entering the lungs. This could cause an Aspiration Pneumonia a serious complication of swallowing difficulties after stroke. 

Notice how the blue liquid enters the trachea at the front of the neck in the abnormal swallow.This then leads down in to the lungs.