chapter 5: cranial nerves to oral cavity

nervous system

extensive, intricate network of neural structures that activate, coordinate, and control all function of the body

2 divisions of the nervous system

-central

-peripheral

cellular component of the nervous system

neuron

2 types of nerves

-afferent

-efferent

afferent nerves

sensory nerve that carries information from the periphery of the body to the brain

efferent nerves

motor nerve that carries information away from the brain to the periphery of the body

CN I

olfactory nerve

olfactory nerve

sensory nerves for smell

CN II

optic nerve

optic nerve

sensory nerves for vision

CN III

oculomotor nerve

oculomotor nerve

motor nerve for eye movement 

CN IV

trochlear nerve

trochlear nerve

motor nerve for eye movement

CN V

trigeminal nerve

trigeminal nerve

largest cranial nerve with both sensory and motor nerves for sensation of face and teeth mastication; has 2 roots a sensory and motor

CN VI

abducens nerve

abducens nerve

motor nerve for eye movement 

CN VII

facial nerve

facial nerve

sensory nerve for taste on anterior 2/3 of tongue and motor nerves for muscles of facial expression, salivation and lacrimation

CN VIII

vestibulocochlear nerve

vestibulocochlear nerve

sensory nerves for balance and hearing

CN IX

glossopharyngeal nerve

glossopharyngeal nerve

sensory nerves for taste and general sensation from the base of the tongue and motor nerves for pharyngeal muscles and parotid gland

CN X

vagus nerve

vagus nerve

sensory nerves for sensation of the ear and motors nerves for muscles of soft palate, pharynx, and larynx

CN XI

accessory nerve

accessory nerve 

motor nerves for shrugging shoulders and head turning as well as muscles of the soft palate and pharynx

CN XII

hypoglossal nerve

hypoglossal nerve

motor nerves for movement of muscles under the tongue

3 parts of the sensory root of trigeminal nerve

-opthalmic division or V1

-maxillary division or V2

-mandibular division or V3

trigeminal nerve ganglion alternative names

Gasserian ganglion or semilunar ganglion

trigeminal nerve ganglion

sensory relay station located in the middle cranial fossa at the base of the skull; it plays a crucial role in transmitting sensory info from the face, head, and oral cavity to the CNS

opthalmic nerve or division enters skull through…

the superior orbital fissure

maxillary nerve or division enters the skull through… 

the foramen rotundum 

mandibular division enters the skull through…

the foramen ovale

the opthalmic and maxillary nerves carry…

only afferent (sensory) nerves

mandibular nerve carries…

both afferent and efferent, a mixed nerve; the sensory root runs together with the motor root 

motor root of the trigeminal nerve

supplies the efferent nerves for the muscles of mastication and then travels with the mandibular nerve of the sensory root of the trigeminal nerve

opthalmic nerve provides…

sensation to upper face and scalp

maxillary and mandibular nerves provide…

sensation to the middle and lower face

opthalmic nerve or V1

smallest division of the sensory root of the trigeminal nerve that serves as an afferent nerve for the conjuctiva, cornea, eyeball, orbit, forehead, ethmoidal and frontal sinuses, part of dura mater, and parts of the nasal cavity and nose

opthalmic nerve gives 3 major nerves

-frontal

-lacrimal

-nasociliary

frontal nerve of opthalmic division

scalp, forehead, upper eyelid

lacrimal nerve of opthalmic division

lacrimal gland, upper eyelid

nasociliary nerve of opthalmic division

cornea of eye, nasal cavity, ethmoid sinus, tip of nose

maxillary nerve or V2

second division from sensory root of trigeminal nerve that carries sensory info for the maxilla and its overlying skin, oral mucosa, maxillary sinuses, nasal cavity, palate, nasopharynx, and part of the dura mater

8 branches of the maxillary division of trigeminal nerve

-infraorbital nerve

-zygomatic nerve

-anterior superior, middle superior, and posterior superior alveolar nerves

-greater and lesser palatine nerves

-nasopalatine nerve

infraorbital nerve (IO) of maxillary division

largest branch of maxillary division and goes to lower eyelid, nose, and upper lip

zygomatic nerve of maxillary division

skin of the cheek and temporal region

anterior superior alveolar nerve or ASA nerve

serves as an afferent nerve for the maxillary central incisors, lateral incisors, and canines as well as associated labial periodontium and gingiva to the midline

ASA nerve origin

from dental branches in pulp of CI, LI, and canine that exit through the apical foramina never also receives interdental branches from the surrounding periodontium

dental plexus

network of nerves within both the maxillary and mandibular dental arches

ASA nerve insertion

ascends along the anterior wall of the maxillary sinus to join the IO nerve within the infraorbital canal

middle superior alveolar nerve or MSA nerve

serves as an afferent nerve for the maxillary premolar teeth and mesiobuccal root of the maxillary first molar also the associated buccal periodontium and gingiva, if nerve is present

MSA nerve origin

if present- from dental branches in pulp that exit the teeth through apical foramina, as well as interdental and interradicular branches of periodontium

MSA nerve insertion

ascends to join the IO nerve by running in the lateral wall of the maxillary sinus

MSA nerve presence

-only in about 28% of the population

-if not present the area is innervated by the ASA and PSA

-if present, there is also communication between the MSA, ASA, and PSA

posterior superior alveolar nerve or PSA nerve

serves as an afferent nerve for the mucous membranes of the maxillary sinus and the maxillary molars with the associated buccal periodontium and gingiva in most cases unless MSA nerve is present

PSA insertion

joins the IO nerve (or maxillary nerve directly in some cases) in the pterygopalatine fossa

ASA, MSA, and PSA are all part of the…

superior dental plexus of maxillary arch

GP nerve location

between the mucoperiosteum and bone of the posterior hard palate

greater palatine nerve or GP nerve or anterior palatine nerve

serves as an afferent nerve for the posterior hard palate and associated palatal periodontium and gingiva of the ipsilateral maxillary posterior teeth

lesser palatine nerve or LP nerve or posterior palatine nerve

serves as afferent nerve for the soft palate and palatine tonsils

GP and LP nerves

move superiorly through the pterygopalatine canal, toward the maxillary nerve in the pterygopalatine fossa. on the way, the palatine nerves are joined by lateral nasal branches

lateral nasal branches

afferent nerves from the posterior nasal cavity

nasopalatine nerve or NP nerve

serves as an afferent nerve for the anterior hard palate and associated palatal periodontium and gingiva of the maxillary anterior teeth bilaterally from maxillary canine to canine, as well as nasal septal tissue

NP nerve location

in mucosa of the anterior hard palate, palatal to the maxillary central incisors

right and left NP nerve 

enters the incisive canal by way of the incisive foramen, thus exiting the oral cavity

mandibular nerve or V3

largest and third nerve division of trigeminal nerve that is a short main trunk within the infratemporal fossa deep to the base of the skull

mandibular nerve is a…

mixed nerve, had both afferent and efferent nerves 

mandibular nerve contains…

the entire efferent part of the trigeminal nerve

branches of the undivided mandibular nerve

-meningeal branches

-medial pterygoid nerve

meningeal branches of mandibular nerve

afferent nerves for parts of the dura mater

medial pterygoid nerve of mandibular division

efferent nerve for the medial pterygoid and tenson veli palatini muscles, as well as a muscle of the middle ear, the tensor tympani

2 trunks of mandibular nerve

-anterior trunk

-posterior trunk

anterior trunk or anterior division of mandibular nerve

formed by the merger of the buccal nerve and additional muscular nerve branches; has both afferent and efferent nerves, mixed nerve

muscular branches part of the anterior trunk of V3

-deep temporal nerve

-masseteric nerve

-lateral pterygoid nerve

deep temporal nerve of anterior trunk of V3

innervates the temporalis muscle

masseteric nerve of anterior trunk of V3

innervates the masseter muscle

lateral pterygoid nerve of anterior trunk of V3

innervates the lateral pterygoid muscle

buccal nerve or long buccal nerve

serves as an afferent nerve for the skin of the cheek, buccal mucosa, as well as the associated buccal periodontium and gingiva of the mandibular molars

pathway of buccal nerve

passes anteriorly to the anterior border of the mandibular ramus and goes between the two heads of the lateral pterygoid muscle to join the anterior trunk of V3

posterior trunk or posterior division of mandibular nerve

formed by the merger of the auriculotemporal, lingual, and inferior alveolar nerves; also a mixed nerve

auriculotemporal nerve

travels with the superficial temporal artery and vein and serves as an afferent nerve for the external ear and scalp

lingual nerve

serves as an afferent nerve for general sensation for the body of the tongue, the floor of the mouth, and the associated lingual periodontium and gingiva of the mandibular teeth to the midline

IA nerve pathway

formed from the merger of the mental and incisive nerves; after forming, it continues to travel through the mandibular canal, along the inferior alveolar artery and vein

the IA nerve is part of the…

inferior dental plexus in mandibular arch

IA nerve exit

through the mandibular foramen and then joined by nearby mylohyoid nerve

inferior alveolar nerve or IA nerve

afferent nerves for the mandibular teeth and associated facial periodontium and gingiva of the mandibular anterior teeth and premolars, as well as labial mucosa through its incisive and mental branches

mental nerve

serves as an afferent nerve for the chin, lower lip, and labial mucosa as well as the associated facial periodontium and gingiva of the mandibular anterior teeth and premolars to the midline

mental nerve enters the skull at the…

mental foramen on the lateral surface of the mandible

incisive nerve

composed of dental branches from the mandibular anterior teeth and premolars 

incisive nerve origin

in the pulp

incised nerve exit

the teeth through the apical foramina, and joins with interdental branches from periodontium and gingiva

incisive nerve is a part of…

inferior dental plexus in mandibular arch

mylohyoid nerve pathway

pierces the sphenomandibular ligament and runs inferiorly and anteriorly in the mylohyoid groove and then onto the inferior surface of the mylohyoid muscle

mylohyoid nerve

serves as an efferent nerve to the mylohyoid muscle and anterior belly of the digastric muscle 

trigeminal neuralgia (TN) or tic douloureux

-no known cause but involves the afferent nerve of the fifth cranial or trigeminal nerve; usually the maxillary or mandibular division but not opthalmic

one theory of TN

that this lesion is caused by pressure on the sensory root of the trigeminal ganglion by area blood vessels