Oral Cavity and Tongue: Comprehensive Anatomy for Dental Practice
Hacı Mert Gökhan
@hacimertgokhan
Overview
The oral cavity (cavitas oris) is the entry point of the digestive system and the primary workspace of dentistry. It is divided by the dental arches into two continuous spaces: the vestibule, a slit between the lips/cheeks and the teeth/gingiva, and the oral cavity proper, bounded by the teeth anteriorly and laterally, the hard and soft palate superiorly, and the tongue and floor of the mouth inferiorly.
Vestibule
- Bounded externally by the lips (orbicularis oris) and buccinator muscle.
- The parotid duct (Stensen's duct) opens into the vestibule opposite the second upper molar — a key clinical landmark for identifying parotid pathology.
- The vestibular sulcus is where local anesthetic infiltration is typically deposited for maxillary and mandibular anterior teeth.
Hard and Soft Palate
- The hard palate is formed by the palatine processes of the maxillae (anterior 2/3) and the horizontal plates of the palatine bones (posterior 1/3).
- The incisive foramen transmits the nasopalatine nerve and vessels; the greater and lesser palatine foramina transmit the corresponding neurovascular bundles supplying the palate — both are important injection sites for palatal anesthesia.
- The soft palate is muscular (levator veli palatini, tensor veli palatini, palatoglossus, palatopharyngeus, musculus uvulae) and elevates during swallowing and speech to separate the oro- and nasopharynx.
Tongue: Muscular Architecture
The tongue is divided by a V-shaped sulcus terminalis into an anterior two-thirds (oral part) and posterior one-third (pharyngeal part).
Intrinsic muscles (superior/inferior longitudinal, transverse, vertical) alter the tongue's shape and have no bony attachment.
Extrinsic muscles alter its position, all innervated by the hypoglossal nerve (CN XII) except palatoglossus (vagus/pharyngeal plexus):
- Genioglossus: protrudes the tongue; the most important muscle to test for CN XII palsy (tongue deviates toward the side of a lower motor neuron lesion).
- Hyoglossus: depresses and retracts the tongue.
- Styloglossus: elevates and retracts the tongue.
- Palatoglossus: elevates the posterior tongue, forming the palatoglossal arch.