Head 3 (nerves) Flashcards
Which cranial nerves carry parasympathetic pre-ganglionic fibers with them
3, 7, 9 (to the head)
10 (to cervical, thoracic, and abdominal viscera)
which cranial nerves are sensory
1, 2, 8
Which cranial nerves are mixed
5, 7, 9, 10
Which cranial nerves are motor
3, 4, 6, 11, 12
List the cranial nerves
1 - olfactory
2 - optic
3 - oculomotor
4 - trochlear
5 - trigemal
6 - abducent
7 - facial
8 - vestibulocochlear
9 - Glossopharyngeal
10 - Vagus
11 - Accessory
12 - Hypoglossal
Which cranial nerves are involved in eating/eliminating
5, 7, 9, 10, 12
which is the largest cranial nerve
Trigeminal n
List the branches of the trigeminal nerve and if they are sensory, motor, or mixed and which foramen each exits
V1 = Opthalmic, sensory (to eye and adnexa), orbital fissure
V2 = Maxillary, sensory, round foramen
V3 = Mandibular, mixed, oval foramen
Origin of Trigeminal n
Motor nucleus: pons
Sensory larger root: trigeminal ganglion
Describe the shape and location of the trigeminal ganglion
aka semilunar ganlion
crescent shape
locates in cranial cavity, outside the brain
What is in the trigeminal ganglion
Is a sensory ganglion containing cell bodies of pseudounipolar sensory neurons, similar to the dorsal root ganglion of the spinal cord. Gives the V1, V2 & the sensory part of V3 (mandibular)
Maxillary nerve origin
Trigeminal ganglion
Maxillary nerve course
Runs on cavernous sinus (with ophthalmic and 3) and passes through round foramen (orbitorotundum in Ru.)
Then goes to alar canal (in canine and equine) and rostral alar f.
to Ptyerygopalatine fossa to maxillar foramen to infraorbital canal and infraorbital f.
Maxillary nerve branches
Zygomatic, Pterygopalatine, infraorbital (continuation of maxillary n)
What are the branches of the zygomatic n
Zygomaticotemporal
Zygomaticofacial
What are the branches of the pteryogopalatine and what do they supply
Lesser palatine - soft palate
Greater palatine - hard palate
Caudal nasal - nasal cavity and maxillary sinus
What does the infraorbital n do
Runs in infraorbital canal and supplies the upper dental arcade via the caudal, middle, and rostral superior alveolar branches and continues outside the canal
What does the infraorbital n divide into and when does it divide
Outside the canal → divides into:
External nasal
Internal nasal
superior labial
What runs in the infraorbital canal and name its two openings
Infraorbital VAN
Caudal opening = maxillary foramen
Rostral opening = infraorbital foramen
Mandibular n course
Passes through oval foramen (foramen lacerum in horse)
short course ventrally to enter mandibular foramen of mandible
passes through mandibular canal and emerges at mental foramina as mental n.
Which main group of muscles does the mandibular n supply?
muscles of mastication (except caudal belly of digastric)
also supplies mylohyoideus, tensor veli palatini, and tensor tympani
List the motor branches of the mandibular n and what muscle they innervate
masticator -> massester m and rostral belly of digastric
deep temporal -> temporalis m
deep pterygoid -> pterygoid mm
mylohyoid -> mylohyoid m
tensory veli palatini -> tensory veli palatini m
tensor tympani n -> tensor tympani n m
List the sensory branches of the mandibular and what area they supply
Auriculotemporal - skin near rostral part of ear and eye (note: Gives sensation to same field for which the dorsal buccal of 7 provides motor innervation)
buccal - inside cheek
lingual - general and special sense of tongue
inferior alveolar - all lower teeth
mental - skin of chin
Describe the auriculotemporal n branches
Branches to transverse facial n and communicating br with dorsal buccal of 7
Facial nerve course
Origin: medulla oblongata at lateral part of trapezoid body
through Stylomastoid foramen
Very superficial under skin on lateral side of face
Which nerve passed through middle ear and can be affected by otitis media
Facial n
What does facial nerve do
Muscles of facial expression
Taste, rostral 2/3 of tongue
secretions (saliva, lacrimal, nasal)
Note: it is the only parasym supply to lacrimal gland
Name the three main branches of the facial nerve
Auriculopalpebral
Dorsal buccal
Ventral buccal
What does auriculopalpebral n do
Motor to orbicular oculi - muscle that closes eyelid
What does supraorbital n do and what is it a branch of
Sensory to upper eyelid
Branch of CN 5 ophthalmic nerve
Glossopharyngeal n origin and foramen
Lateral aspect of medulla oblongata and goes through jugular foramen
Glossopharyngeal n function
motor to pharynx
sensory to pharynx and carotid sinus (baro and chemo receptors)
Special sense for tastes in caudal 1/3 of tongue
parasympathetic to zygomatic and parotid salivary glands
Vagus n origin and foramen
Lateral aspect of medulla oblongata and goes through jugular foramen
note: longest CN
What does vagus n do
parasymp. innervation to viscera of pharynx, nech, thorax, and abdomen
motor and general sensory to soft palate, pharynx, larynx, trahea, esophagus, thoracic viscera, and abdominal viscera
Few special sense (taste from epiglottis)
What are the important branches from the vagus and what do they do
Cr laryngeal n: motor to one laryngeal n, sensory to laryngeal mucosa
Ca. laryngeal n: continuation of the recurrent laryngeal n and motor to laryngeal mm
What does the man’s face represent?
Otic Ganglion
1) Sensory branches (buccal n, lingual n, inf. alveolar n)
2) tensor veli palatini n
3) Temporalis m
4) medial pterygoid m
5) masseter m
6) Lateral pterygoid m
7)Tensor tympani n
How is accessory n unique
only cranial n that does not take part in innervation of head structures
What can occur with a trigeminal nerve injury
Trigeminal Neuritis: Results in sensory deficit of the face and dropped jaw (paralysis of the muscles of mastication).
Note: Wear gloves on dealing with any acute neurologic
disease (like trigeminal neuritis) as rabies is a
differential diagnosis, especially in unvaccinated
animals.
Accessory n course
Passes through F. magnum to join medullary root and exit via jugular. foramen
What are differentials for temporalis and masseter muscle atrophy
Masticatory muscle myositis
Trigeminal neuropathy
What does accessory n do
Motor to omotransversarius, cleidocephalicus, trapezius, and sternocephalicus
1) Auriculotemporal n
2) Mylohyoid n
3) Inferior alveolar
4) Lingual n
Hypoglossal n function
motor to all muscles of tongue
Describe the path of the inferior alveolar n
Enters the mandibular canal → lower dental
arcade
It exits the mental foramina as the mental
nerves.
Hypoglossal n course
Origin: Ventral(not lateral!!) aspect of medulla oblongata (motor nucleus of hypoglossa)
exits hypoglossal canal and runs lateral to ext. carotid a. with linguofacial trunk (horse and ruminant) or lingual a (dog)
Facial nerve sensory innervation
inner pinna
special sensory for taste for rostral 2/3 of tongue
What nerve(s) runs here and name the foramen
Optic (CN 2), optic canal
Facial nerve motor innervation
Motor nerve of the face → mm of facial expression & caudal digastricus m
What nerve(s) runs here and name the foramen
Oculomotor (CN 3) and Trochlear (CN 4)
orbital fissure (orbitorotundum in Ru.)
Facial nerve parasympathetic ganglion and innervation
Pterygopalatine ganglion the innervation to:
Lacrimal gland
nasal glands
palatine glands
Also innervates
Mandibular and sublingual salivary glands
Name this nerve
Trochlear n (CN 4)
What foramen does the facial nerve run though
Sensory, motor fibers run through stylomastoid foramen
parasymp, special sensory fibers run through petrotympanic fissure
What are these nerves branches of? and what is their function?
Branches of Ophtalmic nerve (V1 of trigeminal- all sensory)
1) Supraorbital n
2) frontal n
3) Lacrimal n
4) Nasociliary n
4’) Infratrochlear
What is the chorda tympani n
Arises from the facial n. within the middle ear. It carries special sensory fibers from rostral 2/3 of tongue
(fungiform papillae) & parasympathetic fibers → sublingual & mandibular salivary glands.
Runs with mandibular lingual br
Name nerve and clin sig
Cornual br of infratrochlear n
Important in dehorning in small ru.
Describe the route of the chorda tympani n
It leaves via petrotympanic fissure, and ride with the lingual n. (regular sensory) of mandibular n. → tongue.
1) Infratrochlear n
2) frontal n
1) Dorsal buccal br of 7
2) ventral buccal br of 7
3) Stylomastoid foramen
4) auriculopalpebral n
5) palpebral br
What are these nerves branches of? and what is their function
Branches of Maxillary nerve (V2 of trigeminal- all sensory)
5) maxillary n
6) infraorbital n
7) zygomatic n
8) pterygopalatine n
9) lesser palatine n
10) greater palatine n
11) caudal nasal n
Which nerve runs through the parotid sg
7 (but does not innervate it)
What innervates these sensory regions
1) Ophthalmic n
2) maxillary n
3) mandibular n
Which nerve supplies the parotid sg
CN 9
What are these nerves branches of? and what is their function
Branches of Maxillary nerve (V2 of trigeminal- all sensory)
1) Zygomaticotemporal n
2) Zygomatic n
3) Maxillary n
4) Pterygopalatine n
5) Superior alveolar nn (not a maxillary br)
6) Inferior alveolar n
which cn’s share common entry at internal acoustic meatus and clin sig
7,8
So, vestibular involvement if facial nerve is affected by infection.
1) Infraorbital n
2) Zygomaticotemporal n
3) Zygomaticofacial n
Which nerve supplies the occipitomandibularis m
Facial n
1) Cornual br of infratrochlear n
2) cornual br of zygomaticotemporal n
3) Frontal n
Which nerve is vulnerable in the ruminant while in lateral recumbency
only the dorsal buccal branch
ventral is protected by edges of mandible and masseter
What nerve(s) runs here and name the foramen
Mandibular n of Trigeminal n (CN 5),
Oval foramen (foramen lacerum in horse)
1) Palpebral branches
2) auriculopalpebral n
3) Dorsal buccal br of 7
4) ventral buccal br of 7
What are these nerves branches of? and what is their function
Branches of Mandibular n (V3 of trigeminal - motor and sensory)
13) Masticator n (motor)
14) Deep temporal n (motor)
15) Buccal n (sensory)
16) Deep pterygoid n (motor)
17) Auriculotemproal (sensory)
18) Lingual (sensory)
19) Inferior alveolar (sensory)
19’) Mylohyoid n (motor)
19’’) Mental (sensory)
1) Dorsal buccal br of 7
2) Ventral buccal br of 7
1) Auriculotemporal n
2) Mylohyoid n
3) Inferior alveolar
4) Lingual n
1) Dorsal buccal br of 7
2) Ventral buccal branch of VII
1) Maxillary br (CN 5)
2) Ophthalmic br (CN 5)
3) Facial nerve (CN 7)
4) Mandibular br (CN 5)
5) C2 (Dorsal branch)
in which situations can the facial nerve be affected
Trauma to the face
Parotid salivary gland tumors or infections
Chronic middle ear infections (otitis media)
Auriculopalpebral br of Facial n (CN 7)
What clin sign would be seen if facial n is injured
Unilateral paralysis the lip and nose are pulled to the healthy side due to muscle tone
1) Dorsal buccal br of CN 7
2) Ventral buccal br of CN 7
3) Parotid duct
4) Parotid salivary gland
Which clinical sign if lesion is in central part of facial nerve
If lesions in central parts → affect the whole facial field
* paralysis of ear, eyelids, nose and lip muscles
* Loss of secretions of the lacrimal gland
* Reduce salivary gland secretion.
5) Dorsal buccal br of CN 7
6) Ventral buccal br of CN 7
10) Parotid duct
11) Parotid salivary gland
Which clin signs would be see if lesion is peripheral in facial nerve
Peripheral lesions (in middle ear or outside the skull)
* → unilateral paralysis of muscles of facial expression
* (asymmetrical dropping of the muzzle and inability to close the
eye → keratoconjunctivitis sicca. * In humans → hyperacusis (due to stapedial n paralysis). * In the horse the subcutaneous part of the nerve is damaged by
pressure from a tight halter → paralysis of lips and cheeks.
Which unique response in the horse requires the facial nerve and in which situation may that be harmed
Flehmen
The buccal branches of the facial nerve Cross the lateral aspect of the masseter m. and is susceptible to injury→ facial paralysis
(e.g. a horse lying on a harness buckle during surgery- buccal on buckle)
Describe the facial trigeminal reflex arc
CN7 supplies the motor component to the sensory component of CN5.
Pricking the face with a pin checks this arc.
If either nerve is paralyzed, then a twitch of the muscles will not be elicited.
Describe the parasymp innervation of the glossopharyngeal n
Parasympathetic To dorsally located SGs (parotid, buccal & zygomatic)
Describe general sensory innervation of the glossopharyngeal
middle ear
carotid Sinus & body
cd 1/3 of tongue pharynx
Describe special sensory innervation of the glossopharyngeal
Taste buds on caudal 1/3 of tongue
Describe motor innervation of the glossopharyngeal
Motor to mm of pharynx + branch to stylopharyngeus m. (by itself)
Name the ganglion for the postganglionic neurons (parasymp) in the glossopharyngeal n
Otic ganglion
The postganglionic neurons (parasymp) in the glossopharyngeal n run closely with which other nerve
Mandibular br
Which foramens does the glossopharyngeal nerve exit
Jugular f. & Tympano-occipital fissure
Clin sig of gag reflex
CN9 & CN10 are most important for swallowing - Gag reflex (afferent IX / efferent X)
* Gag reflex deficits as dysphagia may occur due to CN IX or X (loss of afferent pathways
from the laryngeal additus and from loss of motor vagal pathways to the pharyngeal Mm.)
List Ddx for lack of gag reflex
CN IX has no contributions to larynx.
So if larynx is normal, probably 9 is the problem
if larynx affected then 10 is affected
Note: The gag reflex involves complex interplay among the CN 5,9,10 &12
Why do rabies patients have a fear of water
Due to paralysis of the pharynx (9,10)
(therefore, if paralyzed have rabies as a differential)
Where does cn9 travel in the horse
on guttural pouch caudal to stylohyoid bone
What is the nucleus ambiguus
shared motor nucleus for IX, X, and XI
Where does the lingual nerve run and clin sig
crosses the lateral aspect of stylopharyngeus
m. to reach root of tongue.
During its course, it is related to the lateral
aspect of the palatine tonsillar pouch.
Therefore, during surgical removal of the
palatine tonsil, one should consider the
close proximity of this nerve.
What does the lingual n supply
The lingual nerve not only supplies the tonsil,
but also the caudal 1/3 of the tongue with
GVA (temp and nociception) and SVA fibers (vallate and foliate papillae).
Vagus nerve special sensory innervation
special sensory taste to root of larynx, & pharynx, of tongue & epiglottis
Vagus nerve motor innervation
Straited mm of larynx and pharynx (except stylopharyngeus)
Clin sig of vagus motor innervation
The only n. supplying
the larynx -if paralyzed → no
swallowing
Vagus nerve general sensory innervation
Sensory from larynx, pharynx, viscera
Vagus nerve parasymp innervation
to viscera
Where does the vagus nerve exit
Jugular foramen and tympano-occipital fissure
Name the ganglia for the vagus
Proximal and distal ganglia of vagus
Where does vagus run in horses
Over guttural pouch
What can cause vagus nerve problems
Nucleus Ambiguous (motor) lesions- middle part
Descrive hypoglossal n origin, exit, androute
rom the ventral aspect of medulla oblongata
(hypoglossal nucleus) *
Exit via hypoglossal canal
lies lateral to the external carotid artery *
follows the caudal curvature of the styloglossus M.
Which nerves does the hypoglossal run closely with
Runs between 9 & 11
Hypoglossal nerve innervation
Only motor
ALL tongue Mm. + geniohyoideus & sternohyoideus (via ansa cervicalis)
What is the ansa cercicalis and what does it supply
Connection between C1 and CN12 *
This loop supplies:
* Geniohyoideus * Sternohyoideus * Sternothyroideus
What clinical signs are seen with hypoglossal n dysfunction (compare unilateral vs bilateral)
Lack of resistance to pull tongue out of the mouth
* Inability to retract it.
* Dysphagia, animal can’t prehend food or water
unilateral paralysis, the tongue is curved towards the paralyzed
side & atrophied on the paralyzed side.
bilateral (diffuse cerebral damage or diseases of the medulla
oblongata (ex. Neoplasm) may involve the motor nucleus of the
CNXII → tongue paralysis → atrophy of the denervated tongue
muscles) → complete paralysis of the tongue which hangs flaccidly
from the mouth
Where does hypoglossal nerve run in the horse
Passes through the medial compartment of the
guttural pouch (GP), in a common fold with the CN 9.
Guttural pouch disease can affect which cranial nerves and what clinical signs might occur
damage of the
cranial nerves 7, 9, 11 & 12. → can be loss of sensibility & taste up to paralysis of the tongue.
Guttural pouch (name #6-12)
(6) CN IX
(7) internal carotid a. enveloped by fold of (GP) (8) CN XII emerging from hypoglossal canal
(9) CN XI
(10) cranial cervical ganglion
(11) CN X
(12) cervical sympathetic trunk;
