Like all sections of the gastrointestinal tract, the wall of the esophagus is composed of four distinct layers.  The inner mucosa consists of a layer of stratified squamous epithelium lining the lumen of the organ,  the lamina propria and the muscularis mucosae.  The submucosa consists of dense irregular connective tissue and mucus-secreting esophageal glands.  The muscularis externa consists of two thick layers of muscle, an inner circular layer and an outer longitudinal layer.  External to the muscularis is the adventitia (not shown on this image), which consists of fibrous connective tissue that blends into surrounding structures.