It runs along and in the back of the windpipe and it's found in front of our spinal cord. Now, the upper portion of our esophagus consists of skeletal muscle while the rest of it consists of involuntary smooth muscle. And this basically means that although we can actually initiate the process of swallowing and we can actually voluntarily control the movement of food into the upper region of the esophagus, the rest of that movement is controlled, involuntary. We cannot actually control it consciously. And this process by which our smooth muscle is found in our esophagus creates a wavelike motion and allows that bolus of food to actually travel along our esophagus is known as peristaltis. So peristalis is the wavelike contraction of our smooth muscle that propels and allows that food to actually move down our esophagus and ultimately to our stomach.