The lateral walls of the oral cavity are created by the cheeks. Subcutaneous fat creates the bulk of the cheeks, which is then covered with an outer layer of skin. Under the fat are facial muscles, which are adept at assisting in the manipulation of food in the mouth and creating facial expressions, as well as helping manipulate the lips for speech purposes. The inside lining of the cheeks are coated with moist stratified squamous epithelium. The anterior regions of the cheeks meet with the posterior region of the lips, forming a seamless continuation that leads to an opening of the oral orifice.
The lips serve the main purpose of speech related manipulations. They are mostly created of flesh, and have one of the highest mobility factors of all the organs in the human body. They also are capable of performing tasks such as maintain food between the teeth and manipulating food throughout the mouth, as well as suckling in infancy.
The labial frenulum is the midline mucous membrane fold responsible for keeping the lips attached to the inside of the mouth. Both of these folds (upper and lower) can be felt with the tongue. The soft and pliable skin of the lips covers the cover the orbicularis oris muscle and the necessary connective tissue that forms the lips. A transition from the mucous membrane of the mouth and the outer skin of the lips has been deemed the vermilion. Blood vessels within the lips remain chronically close to the skinís surface, giving lips their red or reddish brown coloring. The lips are remarkably sensitive. In order to help determine the texture and temperature of food, the lips have numerous receptors along the skinís surface.
The roof of the mouth is created by the palate. The anterior roof of the mouth is formed by the hard palate, which is bony, and the anterior of the roof of the mouth is created by the soft palate. Two unique plates of the palatine bones, the palatine process of the maxillae and the horizontal plates of the palatine bones, create the hard palate by coming together. These bone plates are then covered by a mucous membrane. Small ridges are created along the hard palate by the transverse palatine folds, or palatal rugae, which provide ample friction for the tongue to maintain its position during the act of swallowing.
The soft palate creates a continuation with the hard palate. It is a soft muscular structure covered by a mucous membrane along the anterior region of the oral cavity. Along the rear middle border of the soft palate, there is a suspended extension known as the palatine uvula. Both the soft palate and the uvula are forced upward when the action of swallowing occurs. This closes off the nasopharynx and prevents food from entering the airway. Along each side of the uvula, there are two muscular folds which protrude downward, are known as the plossopalatine arch (anterior) and the pharyngopalatine arch (posterior.) The palatine tonsil can be found located in between these two muscular folds.