Learning Objective: By the end of this session, the learner will be able to describe the anatomy, boundaries, structures, and functional divisions of the oral cavity, and relate these features to their clinical relevance.
The oral cavity serves as the gateway to the digestive and respiratory tracts and is essential for digestion, speech formation, and breathing. It extends from the oral fissure anteriorly to the oropharyngeal isthmus posteriorly and is divided into the vestibule and oral cavity proper.
Divisions of the Oral Cavity
- Vestibule
- Oral Cavity Proper
Vestibule
The vestibule is the horseshoe-shaped space between the lips/cheeks and the teeth/gums.
- Communicates with the oral cavity proper behind the third molar.
- The oral fissure opens externally, with its diameter controlled by the orbicularis oris muscle.
- Opposite the upper second molar, the parotid duct opens into the vestibule.
Oral Cavity Proper
Located posterior to the vestibule, this space is enclosed by the roof, floor, and cheeks, with the tongue occupying a substantial portion.
Roof
- Hard palate (anterior) – bony structure separating the nasal cavity from the oral cavity; covered by respiratory mucosa superiorly and oral mucosa inferiorly.
- Soft palate (posterior) – muscular structure functioning as a valve; lowers to close the oropharyngeal isthmus and elevates to separate the nasopharynx from the oropharynx.
Cheeks
- Formed primarily by the buccinator muscle, responsible for keeping food between the teeth during mastication.
- Innervated by the buccal branches of the facial nerve (CN VII).
Floor
Consists of:
- Mylohyoid muscles form a muscular diaphragm supporting the floor.
- Geniohyoid muscles – assist in pulling the larynx forward during swallowing.
- Tongue and frenulum – a central muscular organ essential for speech and food manipulation.
- Salivary glands and ducts – contribute lubricating secretions.
