Dental Neuroanatomy
Thursday February 10th, 2011
David A. Morton, Ph.D.
4.B. NASAL AND ORAL CAVITIES
Somatic Sensations of the Face and Head
Objectives:
1. Review and understand the basic anatomy of the following structures for sensory innervation
including central and peripheral pathways:
a. Nasal cavity
b. Paranasal sinuses
c. Palate
d. Tongue
e. Teeth
f. Pharynx
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A. NASAL CAVITY
 Divided into two lateral compartments separated by nasal septum
 Lined with mucous membrane; vascular supply from maxillary, facial, and ophthalmic aa.
 Innervated by branches of the CN I, CN V-1, and CN V-2
 Bordered by the following structures:
 Roof. Cribriform foramina, which transmits CN I for smell
 Nasal septum. Perpendicular plate of the ethmoid bone, vomer bone, and septal cartilage
 Lateral wall. Superior and middle nasal conchae (ethmoid bone) and the inferior nasal concha,
in addition to the maxillary, sphenoid, and palatine bones. The lateral wall contains the
following openings, enabling communication with the nasal cavity:
 Sphenoethmoidal recess. Openings from the sphenoid sinus.
 Superior meatus. Openings from the posterior ethmoidal air cells.
 Middle meatus. Openings for the frontal sinus via the nasofrontal duct, middle
ethmoidal air cells, anterior ethmoidal air cells and maxillary sinus
 Inferior meatus. Opening for the nasolacrimal duct, which drains tears from the eye
into the nasal cavity
 Sphenopalatine foramen. Opening posterior to the middle nasal concha; receives the
nasopalatine nerve and the sphenopalatine artery from the pterygopalatine fossa into
the nasal cavity
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B. PARANASAL SINUSES
Hollow cavities within the ethmoid, frontal, maxillary, and sphenoid bones. They help decrease the
weight of the skull, resonate sound produced through speech, and produce mucus. The paranasal
cavities communicate with the nasal cavity, where mucus is drained. Branches of CN V provide
general sensory innervation.

Ethmoidal Sinus. Consists of numerous small air cells within the bone, as opposed to one or two
large sinuses. Innervated by CN V-1.

Frontal Sinus. The frontal sinus is located in the frontal bone and opens into the anterior part of
the middle meatus via the frontonasal duct. Innervated by CN V-1.

Maxillary Sinus. Largest of the paranasal sinuses; lateral to the nasal cavity and inferior to the
orbit. Opens into the hiatus semilunaris in the middle meatus. Innervated by CN V-2.

Sphenoid Sinus. Contained within the body of the sphenoid bone and is inferior to the sella
turcica. Opens into the sphenoethmoidal recess of the nasal cavity. Innervated by CN V-1 and
CN V-2.
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C. PALATE
Sensory innervation of the palate:


Hard palate. Consists of the maxillary and palatine bones. Sensory innervation is from the
nasopalatine, greater palatine and lesser palatine nerves (CN V-2).
Soft palate. Possess the uvula; ensures that food moves down into the esophagus when
swallowing, rather than up into the nose by acting like a flap-valve. CN V-2 provides sensation
via the lesser palatine nerves.
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D. TONGUE
The following nerves innervate the tongue:
 CN V-3 (lingual nerve). The anterior two-thirds of the tongue receives general sensation from the
lingual branch of CN V-3. The lingual nerve courses inferior to the submandibular duct.
o Chorda tympani nerve (CN VII). Enters the infratemporal fossa via the petrotympanic
fissure, where it joins with the lingual nerve. The chorda tympani nerve provides special
sensory taste from the anterior two-thirds of the tongue, as well as visceral motor
parasympathetic innervation to the submandibular and sublingual salivary glands.
 CN IX (glossopharyngeal nerve). The posterior third of the tongue receives both its general
sensory and special sensory (taste) innervation from CN IX.
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Taste Pathways
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E. TEETH AND GINGIVAE
The teeth cut, grind, and mix food during mastication. Branches of CN V-2 supply the maxillary teeth
and gingivae and branches of CN V-3 supply the mandibular teeth and gingivae.
Innervation of the Maxillary Teeth and Gingivae
 Maxillary teeth. CN V-2 exits the pons and enters the pterygopalatine fossa via the foramen
rotundum. CN V-2 courses into the infraorbital canal, where branches provide general sensory
innervation to the maxillary teeth in a plexus of nerves formed by the anterior, middle, and
posterior superior alveolar nerves.
 Maxillary gingivae. The posterior, middle, and anterior superior alveolar nerves innervate the
buccal surface of the gingivae, whereas the greater palatine and nasopalatine nerves innervate the
lingual surface.
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Innervation of the Mandibular Teeth and Gingivae
 Mandibular teeth. CN V-3 exits the brain and enters the infratemporal fossa via the foramen
ovale. A branch of CN V-3, the inferior alveolar nerve, enters the mandibular foramen and
provides general sensory innervation to the teeth on that side of the mandible. The inferior alveolar
nerve exits the mandibular canal as the mental nerve by traversing the mental foramen and
provides general sensory innervation to the bottom lip.
o Auriculotemporal nerve. Splits around the middle meningeal artery to provide general
sensory innervation to the temporal region of the face and scalp.
 Mandibular gingivae. The long buccal and mental nerves innervate the buccal surface of the
gingivae, whereas the lingual nerve innervates the lingual surface.
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F. PHARYNX
Sensory innervation
 Nasopharynx. Sensory of the nasopharynx via CN V-2
 Oropharynx. Sensory of the oropharynx via CN IX
 Laryngopharynx. Sensory of the laryngopharynx via CN X
Motor Innervation
Neurons originating from the nucleus ambiguous in CN X, course through the jugular foramen and
supply all pharyngeal muscles (except stylopharyngeus). CN IX originates in the nucleus ambiguous
and exits the jugular foramen en route to the stylopharyngeus muscle.
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The gag reflex tests both the sensory and motor components of CN IX and CN X, respectively. This
reflex contraction of the back of the throat is evoked by touching the soft palate, thus blocking entry to
the larynx. The sensory limb of the gag reflex is supplied by CN IX to the brainstem. The motor limb
is supplied by CN X, which results in contraction of the pharyngeal muscles. Absence of the gag reflex
can be a symptom of several severe medical conditions, including damage to CN IX or CN X.
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Identify CN’s I, V, VII, IX, X and XII on the following schematic; trace pathways and identify central
nuclei for each CN.
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