The muscular tube linking the throat to the stomach, down which passes swallowed food and drink. It consists of three coats: a strong outer coat of muscle-fibres in two layers, the outer running lengthwise and the inner being circular; inside this is a loose connective tissue coat containing blood vessels, glands, and nerves; and finally a strong mucous membrane lined by epithelium, which closely resembles that of the mouth and skin. Peristaltic waves (see PERISTALSIS) and mucus secretion from the lining cells help the passage of food.