Oral cavity

Definition

The oral cavity, commonly referred to as the mouth, is the first portion of the digestive system. It is bounded by the lips anteriorly, the cheeks laterally, the palate superiorly, and the floor of the mouth inferiorly. It communicates posteriorly with the oropharynx through the isthmus of fauces.

Anatomical Divisions

The oral cavity is divided into two major parts by the alveolar arches (teeth and gums):

1. Oral Vestibule

The vestibule is the slit-like space between the inner surface of the lips and cheeks and the outer surface (facial/buccal) of the teeth and gingiva.

The parotid duct (Stensen's duct) opens into the vestibule opposite the maxillary second molar.
It is lined by non-keratinized stratified squamous epithelium.

2. Oral Cavity Proper

The oral cavity proper is the space internal to the dental arches.

Roof: Formed by the hard palate (anterior two-thirds) and the soft palate (posterior third).
Floor: Occupied primarily by the tongue and supported by the mylohyoid muscle.
Lateral/Anterior boundaries: The lingual surfaces of the teeth and gingiva.

Major Structures

The Tongue

A muscular organ vital for mastication, deglutition (swallowing), and speech. It is covered in papillae, some of which contain taste buds.

The Palate

Hard Palate: A bony structure formed by the palatine process of the maxilla and the horizontal plate of the palatine bone.
Soft Palate: A muscular flap that closes the nasopharynx during swallowing. The uvula hangs from its posterior margin.

Salivary Glands

While the major glands (parotid, submandibular, and sublingual) are located outside the cavity walls, their ducts open into it. Hundreds of minor salivary glands are located within the oral mucosa.

Clinical Significance

Oral Cancer Screening: Most malignancies occur on the lateral borders of the tongue and the floor of the mouth.
Xerostomia: Subjective feeling of dry mouth, often caused by salivary gland hypofunction.
Stomatitis: Inflammation of the mucous membrane of the mouth.