This presentation was developed by me and another classmate to present some of the major features and characteristics of the nervous system as relating to orofacial structures. We also focused on learning how to make adjustments and adaptations for individuals with nervous system disorders.

1. Nerves and the Nervous System
Oral Implications and Dental Considerations
 Nerves and how they work
 Overview of the different Nervous Systems
 Cranial Nerves
 Focus on Facial and Trigeminal Nerves
 Nervous System Disorders
 Clinical Considerations: Anesthesia
 Case Study: Multiple Sclerosis

2. Nerves
 Neuron: A functional cell of the nervous system. The cell is composed of an axon,
cell body, and dendrite.
 Nerve: A bundle of neurons.
 Afferent Nerve: Sensory nerve that sends signals from the periphery of the
body to the CNS.
 Efferent Nerve: Motor nerve that sends signals from the CNS to the periphery
of the body.
 Ganglion (Ganglia): An accumulation of cell bodies outside the CNS.
 Synapse: A junction between two neurons or between a neuron and an effector
organ.
 Innervaition: A supply of nerves to a body part.

3. How Nerves Work
1. There is an “equal” distribution of electrical charges and ions inside and
outside the neuron cell membrane. The outside of the cell is more positive
(Na) and the inside cell is more negatively charged (K). The charge
difference is called Resting potential. This balance of ions is maintained
by Sodium-Potassium pumps.
2. An Action potential occurs when the cell membrane depolarizes allowing
sodium ions to rush inside the cell. The action potential moves down the
cell at an alarming rate. Sodium and potassium pumps work together to
reestablish resting potential.
3. When a impulse reaches a synapse, the cell uses chemical agents called
Neurotransmitters to relay the impulse to the next nerve or tissue.

5. Central Nervous System (CNS)
 Composed of brain and spinal cord.
 Meninges: membrane that has three layers; Dura mater, arachnoid
mater. And pia mater.
 Cerebrum – two cerebral hemispheres.
 Cerebellum
 Brainstem: Includes medulla, pons, midbrain.
 Diencephalon: Thalamus and hypothalamus.
 Surrounded and protected by bone.

6. Peripheral Nervous System (PNS)
 Network of 43 pairs of
motor and sensory nerves
that connect the brain and
spinal cord to the rest of
their body
 Control functions of
sensation, movement, and
motor coordination
 Includes nerves such as the
femoral, radial, ulnar,
brachial plexus, and sciatic.

7. Autonomic Nervous System (ANS)
 Conveys sensory impulses from the blood vessels, the heart, and all of the
other organs in the chest, abdomen, and pelvis through nerves to other parts
of the brain
 Impulses do not reach our consciousness, elicit mostly automatic or reflex
responses
 Consists of sympathetic and parasympathetic divisions, either fight or flight
or rest and digest.

8. Overview of Cranial Nerves
 12 pairs of nerves that go
directly from the brain to
specific areas of the head
and neck
 Some are involved in
special senses
 Some are involved in
muscle movement and gland
regulation
 Nerves are named and
numbered according to their
location from the front of
the brain to the back

9. Cranial Nerve I/Olfactory Nerve
 Type of Nerve: Afferent – special sensory for smell.
 Origin: Nerve enters the skull through the perforations in the cribriform
plate of the ethmoid bone to join the olfactory bulb in the brain
 Transmitting Foramen: Olfactory Foramina
 Innervates: Transmits smell from the olfactory mucosa to the brain

10. Cranial Nerve II/Optic Nerve
 Type of Nerve: Afferent – special
sense of vision
 Origin: Nerve enters the skull
through the optic canal of the
sphenoid bone on its way to the
retina. Right and left optic nerves
join at the optic chiasma, many of
the fibers cross and continue into
the brain as the optic tracts.
 Transmitting Foramen: Optic
Canal
 Innervates: Transmits sight from
the retinal ganglionic layer to the
brain

11. Cranial Nerve III/Oculomotor Nerve
 Type of Nerve: Efferent
 Origin: Lateral wall of the cavernous sinus, carries preganglionic
parasympathetic fibers to the ciliary ganglion near the eyeball, and
postganglionic fibers to the small muscles inside the eyeball.
 Transmitting Foramen: Superior Orbital Fissure
 Innervates: Two components control muscles for precise eye movement
(Somatic Motor) and control pupillary light and accommodation reflexes
(Visceral Motor).

12. Cranial Nerve IV/Trochlear Nerve
 Type of Nerve: Efferent
 Origin: Runs in the wall of the cavernous sinus and goes to the orbit.
 Transmitting Foramen: Superior Orbital Fissure
 Innervates: The superior oblique muscle of the eye which is responsible
for eye movement, tracking, and fixation on an object

13. Cranial Nerve VI/Abducens Nerve
 Type of Nerve: Efferent
 Origin: Runs through the sinus, close to the internal carotid artery on its
way to the orbit
 Transmitting Foramen: Superior Orbital Fissure
 Innervates: The lateral rectus muscle which is also responsible for eye
movement, tracking, and fixation on an object

14. Cranial Nerve VIII / Vestibulocochlear Nerve
 Type of nerve: Afferent Nerve – Sensory for hearing and balance.
 Origin: The nerve attaches to the brain at the junction of the pons and
medulla oblongata, just lateral to the origin of the facial nerve.
 Transmitting Foramen: Nerve enters cranial cavity through the internal
acoustic meatus of the temporal bone.
 Innervates: Connects brain to inner ear.

15. Cranial Nerve IX / Glossopharyngeal Nerve
 Type of nerve: Efferent and afferent nerve
 Origin: Arises from the anterior portion of the posterolateral sulcus of the
medulla oblongata.
 Transmitting Foramen: Jugular foramen
• Innervates:
 (Efferent) Innervates the pharyngeal muscle, the stylopharyngeus muscle, and the
preganglionic gland parasympathetic innervation for the parotid salivary gland.
 (Afferent) Innervates the oropharynx and deals primarily with taste and general sensation
for base of the tongue and the gag reflex.
 Additionally, the lesser petrosal nerve of IX, synapses with the otic ganglion.

16. Cranial Nerve X / Vagus Nerve
 Type of nerve: Afferent and Efferent nerve.
 Origin: Arises from the lateral aspect of the medulla oblongata just below the ipsilateral
glossopharyngeal nerve. It is the longest cranial nerve.
 Transmitting Foramen: Jugular foramen.
 Innervates:
 (Afferent) Innervates parasympathetically to many organs in the thorax and abdomen such as
the heart, thymus, and stomach. It also innervates the skin around the ear and taste sensation,
and the epiglottis.
 (Efferent) Innervates muscle of soft palate, pharynx, and larynx.

17. Cranial Nerve XI / Accessory Nerve
 Type of nerve: Efferent nerve.
 Origin: Originates as two roots: one from the medulla oblongata adjacent
to the origin of the vagus nerve; the second from the cervical spinal cord.
 Transmitting Foramen: Jugular foramen.
 Innervates: Innervates the trapezius and sternocleidomastoideus muscles.
Additionally, it innervates muscles of the soft palate and pharynx.

18. Cranial Nerve XII / Hypoglossal Nerve
 Type of nerve: Efferent Nerve.
 Origin: Arises as 10 to 15 rootlets from the anterolateral sulcus between
the olive and pyramid of the medulla oblongata.
 Transmitting Foramen: The ipsilateral hypoglossal canal of the occipital
bone.
 Innervates: Innervates muscles the intrinsic and extrinsic muscles of the
tongue.

19. Cranial Nerve VII/Facial Nerve
 Type of Nerve: Afferent and Efferent components
 Origin: The main trunk of the nerve emerges from the skull and gives off two
branches, the posterior auricular nerve and a branch to the posterior belly of the
digastric and stylohyoid muscles. It also sends off small efferent branches to
the stapedius muscle and two other branches to the ear. There are also a
multitude of smaller nerves that go off into the muscles of the face.
 Transmitting Foramen: Mainly the Stylomastoid Foramen
 Branches of the Facial Nerve:
 Greater Petrosal Nerve
 Chorda Tympani Nerve
 Posterior Auricular, Stylohyoid, and Posterior Digastric Nerves
 Temporal Branch
 Zygomatic Branch
 Mandibular Branch
 Buccal Branch
 Cervical Branch

20. Greater Petrosal Nerve
 Type of Nerve: Afferent and Efferent
 Origin: Branch off the facial nerve before it exits the skull, carries
preganglionic parasympathetic fibers
 Innervates: Parasympathetic fibers go to the pterygopalatine ganglion and
then join with branches of the maxillary nerve which is carried to the
lacrimal gland, nasal cavity, and minor salivary glands of the hard and soft
palate. The afferent nerve fibers of the greater petrosal nerve go to the
palate for taste sensation.

21. Chorda Tympani Nerve
 Type of Nerve: Afferent and Efferent
 Origin: Branches off the facial nerve within the petrous portion of the
temporal bone and crosses the eardrum before exiting and traveling down
to the lingual nerve along the floor of the mouth
 Transmitting Foramen: Petrotympanic Fissure (behind the TMJ)
 Innervates: Parasympathetic efferent fibers innervate the submandibular
and sublingual salivary glands, afferent fibers are found in the body of the
tongue for taste sensation.

22. Posterior Auricular, Stylohyoid, and Posterior
Digastric Nerves
 Types of Nerves: All are Efferent nerves
 Origins: Branches of the facial nerve after it exits the stylomastoid
foramen
 Innervates: Posterior auricular nerve goes to the occipital belly of the
epicranial muscle. The stylohyoid innervates the stylohyoid muscle. The
posterior digastric nerve innervates the posterior belly of the digastric
muscle

23. Branches to the Muscles of Facial Expression
 Types of Nerves: All five branches are efferent
 Origins: These branches of the facial nerve originate in the parotid salivary
gland and then go to the muscles they supply
 Innervates:
 Temporal: Muscles anterior to the ear, frontal belly of epicranial muscle, superior
portion of orbicularis oculi, and corrugator supercili
 Zygomatic: Inferior portion of orbicularis oculi and zygomatic minor and major muscles
 Buccal: Muscles of upper lip and nose, buccinators, risorius, and orbicularis oris
 Mandibular: Muscles of lower lip and mentalis muscle
 Cervical: Runs inferior to the mandible to supply platysma

24. Cranial Nerve V / Trigeminal Nerve
 Type of nerve: Efferent and afferent nerve.
 Afferent - The sensory component is thick.
 Efferent - The motor component is thin.
 Origin: Emerges from the inferolateral aspect of the pons. The trigeminal
nerve is the largest cranial nerve in diameter and is composed of a thin
efferent nerve and a thick afferent nerve. At the sight of the trigeminal
ganglion (located within the skull), the nerve divides into three anatomical
branches and exits through transmitting foramen.
 Branches of the Trigeminal Nerve:
1. Ophthalmic Nerve (V1)
2. Maxillary Nerve (V2)
3. Mandibular Nerve (V3)

25. Ophthalmic Nerve (V1)
 Type of nerve: Afferent nerve. Is the smallest division.
 Transmitting Foramen: Superior Orbital Fissure.
 Innervates: Innervates the conjunctiva, cornea, eyeball, orbit, forehead, and ethmoidal and frontal sinsuses.
 Three major nerves:
1. Frontal Nerve – Composed of supraorbital nerve and supratrochlear nerve. This nerve courses along the roof of
the orbit.
2. Lacrimal Nerve – This nerve supplies the conjunctiva and the lacrimal gland. Additionally it also delivers the
postganglionic parasympathetic nerve to the lacrimal gland.
3. Nasociliary Nerve – Composed of several nerves including the infratrochlear nerve, ciliary nerves, anterior
ethmoidal nerve, external nasal nerve, and internal nasal nerves. These nerves innervates the skin of the eyelids,
lacrimal sac, eyeball, and the nose.

26. Maxillary Nerve (V2)
 Type of nerve: Afferent Nerve.
 Transmitting Foramen: Foramen rotundum of sphenoid bone.
 Other nerve branches: within the pterygopalatine fossa the main maxillary trunk
diverges into many nerves, the largest being the infraorbital nerve. Other nerves include
the zygomatic, the anterior, middle, and posterior superior alveolar nerves, the greater
and lesser palatine nerves, and nasopalatine nerves. Additionally, within the
pterygopalatine fossa the pterygopalatine ganglion can be found. This ganglion caries
parasympathetic fibers from the facial nerve, and caries parasympathetic fibers to minor
salivary glands.
 Innervates: Innervates the maxillae, overlying skin, maxillary sinuses, nasal cavity,
palate, and nasopharynx.

27. Maxillary Nerve (V2) Continued
1. Zygomatic nerve – divides into the zygomaticofacial and zygomaticotemporal nerves. It
exits the pterygopalatine fossa through the inferior orbital fissure. These nerve innervate the
skin of the cheeks and the temporal regions.
2. Infraorbital Nerve – Branches into nerves that innervate the upper lip, medial part of the
cheek, lower eyelid, and side of the nose. Emerges from the Infraorbital foramen.
3. Anterior Superior Alveolar Nerve – Innervates maxillary central incisors, lateral incisors,
and canines, as well as the surrounding tissue.
4. Middle Superior Alveolar Nerve – Innervates maxillary premolar teeth and mesiobuccal
root of the maxillary first molar and their associated periodontium and buccal gingiva.

28. Maxillary Nerve (V2) Continued
5. Posterior Superior Alveolar Nerve – Innervates most parts of maxillary teeth,
periodontium, buccal gingiva, and maxillary sinus.
6. Greater Palatine Nerve – Also known as the anterior palatine nerve, its located between
the mucoperiosteum and the bone of the posterior hard palate. Innervates the posterior hard
palate and posterior lingual gingiva.
7. Lesser Palatine Nerve – Also known as the posterior palatine nerve, it innervates the soft
palate and palatine tonsils.
8. Nasopalatine Nerve – Innervates the anterior hard palate, anterior lingual gingiva, and
nasal septum tissue.

29. Mandibular Nerve (V3)
 Type of nerve: Afferent and efferent nerve. This is the largest of the three
branches.
 Transmitting Foramen: Foramen ovale of sphenoid bone.
 Innervates:
 (Efferent) innervates muscles of mastication.
 Muscles of mastication include: Temporal, masseter, and lateral
pterygoid muscles.
 (Afferent) innervates skin, mucous membranes, gingiva, tongue, and
periodontium.
 Several nerve branches arise from the mandibular nerve (V3)

30. Mandibular Nerve (V3) Continued
 Meningeal branches – Afferent nerves for
parts of the dura mater.
 Buccal nerve – Afferent nerve that
innervates the skin of the cheek, buccal
mucous membrane, and buccal gingiva near
mandibular posterior teeth.
 Muscular branches – Efferent Nerves
 Deep Temporal Nerves – two nerves
(anterior and posterior) .
 Masseteric Nerve
 Lateral Pterygoid Nerve
 Medial Pterygoid Nerve – Efferent nerve
that innervates the medial pterygoid, tensor
tympani, and tensor veli palatini muscles.
 Auriculotemporal Nerve – Afferent nerve
that innervates external ear and scalp. This
nerve also caries postganglionic
parasympathetic nerve fibers to the parotid
salivary gland.

31. Mandibular Nerve (V3) Continued
 Lingual Nerve – Afferent nerve that supplies general sensation for the body of the
tongue (anterior 2/3), floor of mouth, lingual gingiva, and mandibular teeth.
 Inferior Alveolar Nerve – Afferent nerve that divides into the incisive and mental
nerves.
 Mental Nerve – Afferent nerve that emerges from the mental foramen and supplies the
chin, lower lip, and labial mucosa.
 Incisive Nerve – Afferent nerve which innervates mandibular premolars and anterior
teeth and periodontal tissue.
 Mylohyoid Nerve – Efferent nerve that innervates the mylohyoid muscle and anterior
belly of the digastric muscle.

32. Disorders of the Nervous System
 The nervous system can be damaged by
trauma, infection, genetic defects,
degeneration, tumors, autoimmune disease, and
blood flow disruption
 Signs of a disorder can be loss of feeling,
tingling, persistent headaches, memory loss,
double vision, weakness, tremors, seizures,
lack of coordination, and change in mental
ability

33. Categories of Nervous System Disorders
 Vascular Disorders: Stroke, transient ischemic attack (TIA),
subarachnoid hemorrhage, subdural hemorrhage and
hematoma, and extradural hemorrhage’
 Infections: Meningitis, encephalitis, polio, and epidural
abscess
 Structural Disorders: Brain or spinal cord injury, Bell's
palsy, cervical spondylosis, carpal tunnel syndrome, brain or
spinal cord tumors, peripheral neuropathy, and Guillain-Barré
syndrome
 Functional Disorders: Headache, epilepsy, dizziness, and
neuralgia
 Degeneration: Parkinson's disease, multiple sclerosis,
amyotrophic lateral sclerosis (ALS), Huntington's chorea, and
Alzheimer's disease

34. Case Study: Oral Implications of MS
 Multiple Sclerosis is an autoimmune disorder
that affects about 400,000 people in the U.S.
 Affects Central Nervous System by damaging
myelin sheath around the nerves
 Symptoms may include numbness, tingling,
weakness, fatigue, dizziness, blurring vision
 Oral manifestations commonly include
paresthesia and facial palsy

36. Case Study: Oral Implications of MS
 54 year old Caucasian male with MS since the age of 19
 Healthy gingival tissues with slight xerostomia (due to
medications), slight bleeding on probing
 Severe attrition and some hyperkeratinization due to
bruxism from muscle spasticity
 Plaque score of 57% with most of it found
interproximally
 Very motivated and educated patient who just needed
slight adjustments for better oral care
 Showed how to angle brush 45 degrees and floss in a C
shape for improved plaque removal
 Every patient is an individual and needs an individual
treatment plan, help those who have chronic illnesses
improve their oral health

37. Review
 Nerves control what we feel, how we feel it, and how we respond
to it.
 The nervous system has different divisions and each are
interrelated and have coordinating functions
 We have 12 pairs of cranial nerves that have special sensory,
motor, and regulatory functions
 The facial and trigeminal nerves are absolutely essential to
understand as dental professionals
 It is important to understand nervous system disorders and nerve
damage when dealing with people who have chronic illnesses or
conditions or when administering anesthesia.

38. References
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http://www.youtube.com/watch?v=K_qjguv2Wtg
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http://www.yale.edu/cnerves/contents.html
Homan, D. P., Shively, M. J. (2008). Fundamental Concepts of Human
Anatomy. Eden Prairie, Minnesota: Bluedoor, LLC.

39. References
Overview of Nervous System Disorders. (n.d.). Retrieved November 10,
2014, from
http://www.hopkinsmedicine.org/healthlibrary/conditions/nervous_system
_disorders/overview_of_nervous_system_disorders_85,P00799/
Peripheral Nerve System. (n.d.). Retrieved November 10, 2014, from
http://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/
peripheral_nerve_surgery/conditions/peripheral_nerve_system.html
Reich, M., & Campbell, P. (2010, January 1). The Oral Implications of MS.
Retrieved November 10, 2014, from
http://www.dimensionsofdentalhygiene.com/ddhright.aspx?id=6992
Rubin, M. (2014, October 1). Overview of the Cranial Nerves. Retrieved
November 10, 2014, from
http://www.merckmanuals.com/home/brain_spinal_cord_
and_nerve_disorders/cranial_nerve_disorders/overview_of_the_cranial_ne
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Streeten, D. (n.d.). The Autonomic Nervous System. Retrieved November 10,
2014, from http://www.ndrf.org/ans.html