Oral cavity

Last updated: November 13, 2023

Summarytoggle arrow icon

The mouth is the facial opening of the gastrointestinal tract. The oral cavity, which is bounded by the lips anteriorly, cheeks laterally, and the oropharynx posteriorly, encloses the tongue, palates, gums, and teeth. The mouth's primary function is the initiation of the digestion process, which involves ingestion, chewing to break down food (mastication), the release of digestive enzymes from the salivary glands into the oral cavity, and swallowing (deglutition). Secondary functions include taste (gustation), sound production and speech articulation, ventilation, facial expression, and touch. The oral cavity can be anatomically divided into the oral vestibule, the space between the teeth and the mucosa of the lips and cheeks, and the oral cavity proper, the space bounded anteriorly and laterally by the teeth and posteriorly by the oropharynx. The teeth are hard, calcified structures used for sound articulation as well as biting and masticating food. The oral cavity is separated from the nasal cavity by the palate, which is divided into the soft and the hard palate. The masticatory movements of the jaw are enabled by the muscles of mastication, and swallowing is facilitated by the palatine muscles. The tongue is the organ responsible for the gustatory sense, which occurs via stimulation of the taste buds situated in the lingual papillae. The oral cavity is, furthermore, a secondary respiratory channel, which communicates with the nasal cavity posteriorly.

Anatomytoggle arrow icon


The oral cavity is divided into two spaces: the oral vestibule and the oral cavity proper.

Anatomical boundaries

Anatomical structures

Structures of the oral cavity
  • Form the oral fissure, which is the opening of the oral cavity
  • Can be divided anatomically and histologically into three regions: external facial skin, vermillion zone, and internal mucosa.
Oral (buccal) mucosa
Intermaxillary commissure
  • Hard, calcified structures used to break down food
  • Embedded in the alveolar processes of the mandible and maxilla (see “Teeth” below)
Salivary glands
  • Consists of an anterior, bony part (hard palate) and a posterior muscular part (soft palate)
  • Separates the oral cavity from the nasal cavity (oral cavity roof)
  • Muscles of the soft palate are involved in ventilation and deglutition
  • Both hard and soft palates are important for sound production and speech articulation (see “Palate” below)

Lipstoggle arrow icon


The lips form the oral fissure, which is the opening of the mouth leading into the oral vestibule.


Can be divided anatomically and histologically into three regions:

Embryology [1][2][3]

  • Development of the upper lip
    • The maxillary prominences grow medially and fuse with the lateral nasal prominence, giving rise to the lateral parts of the upper lip.
    • The maxillary prominences continue to grow medially and fuse with the medial nasal prominence on either side; , bringing the nostrils closer together at approx. 5 weeks' development; disruption of this process leads to cleft lip.
    • Fusion of the medial nasal prominences forms the philtrum and middle ⅓ of the upper lip, the primary palate, the central nose, and the nasal septum
  • Development of the lower lip: Fusion of the right and left mandibular processes forms the lower lip and the mandible

Teethtoggle arrow icon


  • Food break-down into smaller particles, which facilitates digestion and absorption
  • Sound production and speech articulation

Types of teeth according to age

  • Primary teeth (also known as deciduous teeth or milk teeth)
    • Develop during embryogenesis, erupt during infancy, and shed by the age of 6–12 years
    • Five in each quadrant (right, left, upper, and lower) 20 in total
  • Permanent teeth
    • Usually completed by 13 years of age
    • Eight in each quadrant (right, left, superior, and inferior), 32 in total
    • Wisdom teeth (vestigial third molars)
      • Usually erupt by the age of 17–38 years
      • One in each quadrant (right, left, superior, and inferior), 4 in total
      • Partial eruption may cause inflammation and infection in the surrounding gingiva (pericoronitis), which are often indications for extraction.
    • Developmental alterations may affect the number, size, shape, and structure of permanent teeth.
      • Hypodontia: the congenital absence of one or more teeth
      • Hyperdontia: the condition of having one or more extra teeth (supernumerary teeth)

Types of teeth according to function

Type Characteristics
  • Primarily used for grinding of food
  • Contain 3–5 cusps
  • Upper molars have 3 roots and attach to the maxilla.
  • Lower molars have 2 roots and attach to the mandible.
  • Primarily used for grinding of food
  • Contain 2 cusps
  • Contain a single root
  • The first upper premolar can be bifid.
  • Primarily used for tearing of food
  • Contain a single downward cone-shaped prominence
  • Contain a single root
  • Primarily used for biting and cutting food
  • Contain a single root
  • The free end is shaped like a chisel.



Part Characteristics
  • Located between the crown and the root
  • Located in the alveolar surface of the mandible and/or maxilla
  • Connected to the bone by the periodontal ligament (a type of modified periosteal layer)
  • Covered with cementum
  • Mandibular molars have 2 roots.
  • Maxillary molars have 3 roots.


Structure Characteristics
  • The outer layer of the tooth that covers the crown
  • Develops from the surface ectoderm
  • Produced by ameloblasts
  • Whitish, yellowish, or grayish in color
  • Hardest part of the tooth
  • Most highly mineralized substance in the human body
  • Primarily composed of hydroxyapatite
  • Does not contain collagen
  • Can be damaged and degraded by acids in food and drinks
  • Does not contain blood vessels or nerves

Gingivatoggle arrow icon


  • Definition: a mucosal tissue that covers the following:
  • Description: pinkish color (can be pigmented in dark-skinned individuals)
  • Types: can be divided into the following 2 types:
    • Attached gingiva
      • Keratinized tissue that is firmly attached to the bone structure
      • Fills the interdental spaces beneath each tooth to form the interdental papillae
    • Free gingiva: forms a collar around the tooth but is not directly attached to the tooth surface


  • Protection of the root of the teeth and the underlying bone from mechanical insults and infections
  • Modulation of inflammatory response and tissue repair


  • Buccal (outer, anterior) surface
    • Maxillary (superior) side: innervated by branches of the infraorbital nerve (anterosuperior, middle, and posterior branches)
    • Mandibular (inferior) side: innervated by the mental and buccal nerves
  • Lingual (inner, posterior) surface
    • Maxillary (superior) side: innervated by the nasopalatine and greater palatine nerves
    • Mandibular (inferior) side: innervated by lingual nerves

Tonguetoggle arrow icon




The tongue consist of the following layers:

Lingual papillae

Lingual papillae type Characteristics Innervation
Filiform papillae
  • Most numerous type of the lingual papillae
  • Follow the V shape of the sulcus terminalis throughout the anterior two-thirds of the tongue, becoming more transverse at the tip of the tongue
  • Slender, small, and conical in shape
  • The only keratinized papillae
  • Responsible for
    • Sensation of touch
    • Increasing friction between the tongue and the food to facilitate mastication and digestion
  • The only papillae without taste buds
Fungiform papillae
  • Located on both sides of the body of the tongue and the apex
  • Mushroom-shaped
  • Deep red color is due to highly vascularized connective tissue core
  • Contain very few taste buds
Foliate papillae
  • Located in front of the palatoglossal arches and the lingual tonsils, on both sides of the tongue
  • Rudimentary in humans
  • Leaf-shaped
  • Contain abundant taste buds
Circumvallate papillae
  • The largest of the papillae
  • 8–12 in number
  • Follow the V shape of the sulcus terminalis anteriorly
  • Dome-shaped (narrower at the base and larger at the apex)
  • Surrounded by a slight circular mucosal elevation (vallum or wall) which is separated from the papilla by a circular sulcus
  • Covered by stratified squamous epithelium
  • Contain abundant taste buds

Lingual tonsils

Muscles of the tongue

Extrinsic muscles of the tongue

The extrinsic muscles of the tongue originate outside of the tongue.

Muscle Origin Insertion Innervation Function
  • Posterolateral sides of the tongue
  • Protrusion and depression of the tongue

The genioglossus normally protrudes the tongue evenly in the midline, but if there is unilateral hypoglossal damage, the tongue will deviate towards the side of the damage.

The Genie propels out of the bottle (the genioglossus protrudes the tongue).

Intrinsic muscles of the tongue

The intrinsic muscles of the tongue originate and insert within the tongue.

Muscle Origin Insertion Innervation Function
Superior longitudinal muscle
Inferior longitudinal muscle
Vertical muscle
  • Flattens and broadens the tongue
Transverse muscle of the tongue
  • Median fibrous septum
  • Narrows and elongates the tongue

Blood vessels and nerve supply of the tongue

Structure Characteristics
Arterial supply
Venous drainage

All of the tongue muscles (intrinsic and extrinsic) are innervated by the hypoglossal nerve (CN XII), except for the palatoglossus (CN X).


Structure Characteristics

Anterior two-thirds of the tongue

Posterior one-third of the tongue
Foramen cecum (tongue)
  • Located at the intersection between the sulcus terminalis and sulcus medianus
  • Site of embryonic origin of the thyroglossal duct
Muscles of the tongue

Palatetoggle arrow icon


  • The palate divides the oral cavity from the nasal cavity.
  • Constitutes the roof of the mouth and contributes to the floor of the nose

Anatomy of the definitive palate

Structure Characteristics
Hard palate
Soft palate

Muscles of the palate

Muscle Origin Insertion Innervation Function
Tensor veli palatini

Levator veli palatini

Musculus uvulae
  • Posterolateral side of the tongue

In vagus nerve (CN X) lesions, the uvula deviates away from the side of the lesion.

Embryology (development of the palate)

  • 4th week of development
    • Downward proliferation of the mesoderm covering the forebrain → formation of the frontonasal prominence
    • Local thickening of the surface ectoderm on both sides of the frontonasal prominence → formation of the nasal placodes
  • 5th week of development: : invagination of the nasal placodes → formation of medial and lateral nasal prominences
  • 6th–7th week of development
  • 7th–8th week of development: fusion of the primary and secondary palates; at the level of the incisive foramen → formation of the permanent palate
Structure Formation Developmental defects
Primary palate
  • Formed through the fusion of the medial nasal prominences in the midline with palatine processes
Secondary palate
Permanent palate
  • N/A

Salivary glandstoggle arrow icon

In addition to the three larger paired glands (parotid, submandibular gland, and sublingual glands), there are several hundred small salivary glands in the oral cavity and throat. As secretory glands, they secrete up to 1.4 L of saliva per day. The primary functions of saliva include:

  • Digestion
  • Protection of the mucosa and teeth
  • Immunological defense
  • Transport of soluble flavors to the taste buds

Parotid gland

  • Located on the surface of the masseter muscle, dorsal to the mandibular ramus and ventrocaudal to the external auditory canal in the retromandibular fossa.
  • Subdivided by the branches of the facial nerve which runs through the parotid gland
  • Its salivary duct (Stensen duct) runs forward along the masseter muscle and opens adjacent to the 2nd molar in the vestibule of the mouth (the space between the cheeks and the teeth).
  • Produces mainly serous fluid and ∼ 40% of the total amount of saliva.

Submandibular gland

Sublingual gland

  • Located medial to the mandible above the mylohyoid muscle and below the sublingual fold
  • Its main salivary duct also ends in the Wharton duct
  • Produces mainly mucous fluid

Masticationtoggle arrow icon

Muscles of mastication

Muscle Origin Insertion Innervation Function Embryology
  • Zygomatic arch (lower and medial surface)
Lateral pterygoid
  • Bilateral contraction
  • Unilateral contraction: laterotrusion (sideways movement) of the mandible to the contralateral side
Medial pterygoid


To remember the muscles of mastication that close the mouth: “Resist the TEMPtation to eat yuMMy food!” (TEMP = Temporalis; M = Masseter; M = Medial pterigoyd)

Deglutitiontoggle arrow icon

Phase Characteristics
Oral phase (deglutition)
Pharyngeal phase (deglutition)
Esophageal phase (deglutition)
  • Involuntary process
    1. Contraction of the pharyngeal constrictor muscles (superior, middle, and inferior) → propulsion of the bolus of food downward to the esophagus
    2. Esophageal peristalsis propulsion of the bolus of food towards the stomach
  • Affected by achalasia

Taste (gustation)toggle arrow icon


Anatomy of taste

Gustatory pathway

The nerves responsible for taste transmit information to the solitary nucleus in the medulla, which in turn projects to three different brain areas:

Taste papillae and taste buds

Physiology of taste

Types of taste Tastant Mechanism Function
  • Ions (e.g., Na+, NH4+, K+, SO42-, Cl)
  • Hydrogen ions (H+)
  • Hydrogen ions enter the cell via transmembrane ionic channels → acidic intracellular environment → generation of action potentials in nerve fibers → brain perception of sour taste
  • Warning signal for toxins
  • Increase appetite for calorie-dense foods
  • Warning signal for toxins
Umami (savory)
  • Increase appetite for protein-rich foods

Clinical significancetoggle arrow icon

Neurologic disorders

Inflammatory and infectious diseases

Immunologic disorders

Congenital diseases and dysmorphisms

Neoplastic disorders

Dental injuries

Other disorders

Referencestoggle arrow icon

  1. Kandel E, Schwartz J, Jessell T. Principles of Neural Science, Fourth Edition. McGraw-Hill Medical ; 2000
  2. Craniofacial Development. Updated: December 12, 2016. Accessed: April 26, 2018.
  3. $Facial and palatal development.
  4. Development of the Palate. . Accessed: April 26, 2018.
  5. Standring S. Gray's Anatomy: The Anatomical Basis of Clinical Practice. Elsevier Health Sciences ; 2016
  6. Sadler TW. Langman's Medical Embryology. LWW ; 2018
  7. Douglas D. Damm; Jerry E. Bouquot; Brad Neville; Carl M. Allen. Oral & Maxillofacial Pathology. W B Saunders Company ; 2002
  8. Prada CE, Zarate YA, Hopkin RJ. Genetic Causes of Macroglossia: Diagnostic Approach. Pediatrics. 2012; 129 (2): p.e431-e437.doi: 10.1542/peds.2011-1732 . | Open in Read by QxMD
  9. Palate. Updated: December 31, 2018. Accessed: March 4, 2020.
  10. Núñez-Martínez PM, García-Delgado C, Morán-Barroso VF, Jasso-Gutiérrez L. Congenital macroglossia: clinical features and therapeutic strategies in pediatric patients. Bol Med Hosp Infant Mex. 2016; 73 (3): p.212-216.doi: 10.1016/j.bmhimx.2016.03.003 . | Open in Read by QxMD

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