Final answer:
The esophagus is a muscular tube that connects the pharynx to the stomach. It does not contain glands, but it has two types of muscle: an inner circular layer and an outer longitudinal layer. The main function of the esophagus is to transport food from the mouth to the stomach.
Step-by-step explanation:
The esophagus is a muscular tube that connects the pharynx to the stomach. It is approximately 25.4 cm (10 in) in length, located posterior to the trachea, and remains in a collapsed form when not engaged in swallowing. The inner lining of the esophagus consists of a mucous membrane, which provides a smooth, slippery surface for the passage of food.
The esophagus does not contain glands but has two types of muscle: an inner circular layer and an outer longitudinal layer. These muscles work together to propel food towards the stomach through peristaltic contractions. The circular muscles contract behind the bolus of food, pushing it forward, while the longitudinal muscles contract in front of the bolus, shortening the esophagus and widening its lumen to allow easier passage of food.
The main function of the esophagus is to transport food from the mouth to the stomach. It does not participate in the process of digestion or absorption of nutrients. Instead, it acts as a conduit, utilizing muscular contractions to push the food down the gastrointestinal tract.