The palate forms the roof of the mouth separating the oral and nasal cavities. It consists of a hard palate (anterior bony portion) and a soft palate (posterior muscular portion. The hard palate takes the form of a thin horizontal bony plate with the following features:

Mucosa (mucous membrane): It is composed of stratified squamous non-keratinized epithelium. The large ridges that project into the oral cavity are called rugae; it aids in holding the food in your mouth. The small ridges are called dermal papillae. These small ridges are composed of connective tissue that projects towards the epithelium. The dermal papillae reduce the mobility of the epithelium by expanding the contact between the epithelium and the underlying connective tissue. It also brings the blood vessels in close contact with the epithelial cells.

Submucosa: Composed of dense irregular connective tissue supporting the epithelium. It tightly adheres to the periosteum of the underlying bone. On the submucosa, you’ll find minor salivary glands composed of mucous cells and secretory ducts.

The tongue is covered by a specialized mucosa that contains multiple types of papillae and taste buds. It contains the following features:

Stratified squamous non-keratinized epithelium which contains the dermal papillae. Ridges of connective tissue that project into the the epithelium, reducing its mobility and brings the blood vessels in close contact with the epithelial cells.

Folliate papillae: parallel ridges on lateral edges of the tongue separated by deep mucosal furrows. This is where you’ll find your taste buds, elliptical structures that contain cells with taste receptors.

Skeletal muscle: arranged in three bundles at right angles to each other to allow flexibility and precision in movements of the tongue.

Minor salivary glands: composed of serous glands and mucous glands that are found throughout the tongue. Serous glands secrete a fluid that contains digestive enzymes, whereas mucous glands secrete mucin.

The esophagus is a muscular tube through which food passes from the pharynx to the stomach. It is composed of four layers:

Mucosa: Composed of stratified squamous non-keratinized epithelium, lamina propia (dense irregular connective tissue) and, muscularis mucosae (smooth muscle).

Submucosa: dense irregular connective tissue that contains mucus glands and ducts.

Musclaris externa: made up of smooth and skeletal muscles and forms the middle third of the esophagus. It is composed of an inner layer of circular muscle cells, an outer layer of longitudinal muscle cells, and the Auerbach’s plexus which can be found in between the inner and outer layer of the plexus.

Adventitia: carries blood vessels and nerves to the wall of the digestive system. It is not visible in my histology art of the esophagus.