Anatomy of the Oral Cavity

Study Notes

The roof of the oral cavity consists of the palate, which has two parts: anterior hard palate and posterior soft palate.
The hard palate is formed by the palatine processes of the maxillae (anterior three-quarters) and the horizontal plates of the palatine bones (posterior one-quarter).
The hard palate is continuous with the soft palate posteriorly and is covered by a tightly bound layer of oral mucosa.
The hard palate separates the oral cavity from the nasal cavities.

The mucosa of the hard palate possesses numerous transverse palatine folds (palatine rugae) and a median longitudinal ridge (palatine raphe).
The palatine raphe ends anteriorly in a small oval elevation (incisive papilla).
The incisive papilla overlies the incisive fossa formed between the horizontal plates of the maxillae immediately behind the incisor teeth.

The mandible is the bone of the lower jaw, consisting of a body and two rami.
The hyoid bone is a small, U-shaped bone in the neck between the larynx and the mandible.

The tongue is composed of muscle, completely divided into a left and right half by a median sagittal septum.
The tongue has intrinsic and extrinsic muscles.
Intrinsic muscles contribute to precision movements of the tongue required for speech, eating, and swallowing.
Extrinsic muscles originate from structures outside the tongue and insert into the tongue, protruding, retracting, depressing, and elevating the tongue.

Genioglossus: originates from the superior mental tubercles, causes the tongue to protrude and depresses the central part.
Hyoglossus: originates from the greater horn and body of the hyoid, depresses the tongue.
Styloglossus: originates from the styloid process of the temporal bone, retracts the tongue and pulls it superiorly.
Palatoglossus: originates from the palate, elevates the tongue, moves the palatoglossal arch toward the midline, and depresses the soft palate.

The lingual artery, from the external carotid artery, is the main artery.
The dorsal lingual and deep lingual veins join the internal jugular vein.
The pharyngeal part of the tongue drains to the jugulodigastric node, while the oral part drains directly into the deep cervical nodes and indirectly through the submental and submandibular nodes to the deep cervical nodes.

The soft palate acts as a valve that can be depressed to help close the oropharyngeal isthmus or elevated to separate the nasopharynx from the oropharynx.
The smaller, deep part of the soft palate lies within the floor of the oral cavity.
The submandibular duct emerges from the medial side of the deep part and moves forward to open near the frenulum of the tongue.

Sublingual gland: the smallest of the salivary glands, located immediately lateral to the submandibular duct, and drains into the oral cavity through numerous small ducts.
Parotid gland: the largest gland of the paired salivary glands, located outside the boundaries of the oral cavity, produces a watery saliva and salivary amylase.

The parotid gland is enclosed within the split investing layer of deep cervical fascia.
The parotid duct leaves the anterior edge of the parotid gland, crosses the face, and opens into the oral cavity near the 2nd upper molar tooth.
The parotid gland has important relationships with the facial nerve, external carotid artery, and its branches.