Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

The Science of Viscera (Splanchnology)
Digestive System
Oral Cavity

The Oral Cavity is divided into two sections: the oral vestibule and the oral cavity proper. The vestibule is bounded by the Lips anteriorly, the Cheeks laterally, and the Teeth and Gums internally. It opens to the exterior via the oral fissure, which is bounded by the lips. The outer surface of the lips is covered with Skin, while the inner surface is lined with mucous membrane, distinguishing an outer cutaneous part and an inner mucosal part. There is also an intermediate zone covered with a thin layer of keratinized stratified squamous epithelium and devoid of mucous glands and Hair.

The oral cavity proper lies internal to the teeth and gums and communicates with the vestibule through the interdental spaces. Its superior wall is formed by the hard palate and the soft palate, both covered with mucous membrane. The soft palate, or palatine velum, attaches posteriorly to the hard palate and terminates posteriorly in a narrow projection called the uvula. Two pairs of folds, or arches, extend laterally and inferiorly from the soft palate: the posterior palatopharyngeal arch and the anterior palatoglossal arch. Located between the arches on each side is the palatine tonsil, an organ of The Immune System. The floor of the oral cavity is formed by the oral Diaphragm, which consists of the paired mylohyoid Muscles fused along the midline, supporting the Tongue. A fold known as the frenulum of the tongue is formed where the mucous membrane reflects onto its inferior surface. The ducts of the Salivary Glands open on each side of the frenulum at the summit of the sublingual caruncle.

Posteriorly, the oral cavity communicates with the Pharynx through the ISTHMUS OF THE fauces, which is bounded superiorly by the soft palate, laterally by the palatine arches, and inferiorly by the ROOT of the tongue.

In a newborn infant, the oral cavity is relatively small. Since teeth are not yet present, the vestibule is separated from the oral cavity proper by the gingival margins. The infant's lips are thick and the cheeks are rounded due to a well-developed sucking pad (fat body of the cheek). Starting at four years of age, this fat body partially atrophies and gradually decreases in size. The hard palate is flat, and its mucous membrane contains few glands. The soft palate is relatively wide and short, lying almost horizontally. Because the soft palate does not reach the posterior pharyngeal wall, the infant can breathe freely while suckling.