Cranial Nerves Flashcards
Which cranial nerves carry autonomic nerves/parasympathetic fibers with them
3, 7, 9 (to the head)
10 (to cervical, thoracic, and abdominal viscera)
Which cranial nerves run with sympathetic fibers
9, 10, 11, 12
What is cranial nerve #0
Terminal nerve
passes through cribriform plate and responsible for pheromones
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 a part of the CNS
CN 1 and 2
Desrcibe the olfactory nerve
Made from numerous unmyelinated axons
Bipolar olfactory neurons replaced monthly
Only cranial nerve that does not have a nucleus in the brainstem
Enters though cerebrum (not brainstem/thalamus)
Origin of olfactory nerve
Cell bodies (receptors) in olfactory mucosa in ethmoidal conchae and vomeronasal organ
Course of olfactory nerve
leave nasal fundus via cribriform plate of ethmoid and then fibers collect together to form the olfactory bulb
Olfactory bulbs form olfactory stria which then goes to piriform lobe
Describe optic nerve
Not a true peripheral nerve
Part of brain and it is a tract enveloped by meninges and the dura blends with the sclera
Optic nerve origin
Ganglion cells of the retina
optic nerve course
Axons converge toward optic papilla to form optic nerve which exit the retina at the optic disc
Optic nerve enters the skull at the optic canal
The nerve from each eye cross at the optic chiasm where median fibers cross to the other side while lateral ones do not
The nerves continue as the optic tract which end in the lateral geniculate nucleus (LGN) in the thalamus then to the occipital lobe
term for medial optic nerve in the optic chiasm
Nasal
Term for lateral optic nerve in the optic chiasm
Temporal
Describe the oculomotor nerve
Purely motor
Carry parasympathetic fibers
Somatic motor: carries general somatic efferent (GSE) motor fibers to several extra-ocular muscles
Visceral mototr: carries general visceral efferent (GVE) parasympathetic fibers to pupillary sphincter constrictor m. (miosis) and to ciliary muscles (control thickness of lens)
Oculomotor origin
Motor nucleus and parasympathetic nucelus in midbrain
Oculomotor course
Leaves midbrain between cerebral peduncles
Travels in cavernous sinus with trochlear, opthalmic, and abducent nerves (4,5,6)
Leave cranial cavity through orbital fissure (orbitorotundum in ruminants)
Enters pterygopalatine fossa and courses rostrally to supply structures in orbit
Name the ganglion for the parasympathetic fibers of the oculomotor nerve
Ciliary ganglion
What is unique to trochlear nerve
smallest cranial nerve
only cranial nerve to emerge from dorsal side of brainstem
only cranial nerve to decussate (cross midline) entirely to innervate contralateral side
What muscle does the trochlear nerve innervate
Superior Oblique m
Where does the trochlear nerve exit
via the orbital fissure (orbitorotundum in rum.)
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
What are the branches of the ophthalmic nerve
Lacrimal, Nasociliary, Frontal
Function of lacrimal nerve
Parasymp to lacrimal gland
sensory to skin and conjunctiva of the lateral angle of the eye
What are the branches of the nasociliary nerve
infratrochlear, long ciliary n, ethmoidal n
Which nerve is important in dehorning in small ruminants vs large
Small: cornual branch of infratrochlear nerve
Large: Cornual branch of zygomaticotemporal nerve
What does the nasociliary nerve supply
Sensory to the parts of the eye and nasal cavity
What does the frontal nerve supply
Sensory to most of forehead and mucosa of frontal sinus
Name the important branch of the frontal nerve and what is supplies
Supraorbital nerve
Sensory to upper eyelid and skin near lateral angle
Supraorbital nerve species differences
Present in all species
In Eq and Ru ot emerges through supraorbital foramen which is accessible/palpable here for nerve blocks
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
Describe the Zygomatic n course and branches
Passes through orbit and exits near orbital lig or postorbital bar
Divides into zygomaticotemporal n and zygomaticofacial n
What does zygomaticotemporal n do
Supplies skin of temporal region and laterally in the upper eyelid and skin of forehead to the midline
major supply to the horn of cattle (cornual branch) - crossing temporal line of skull
What nerves supply the horn in cattle
Main one: cornual branch of zygomaticotemporal n
also cornual branch of infratrochlear n and frontal nerve if horns are large (cannot be blocked)
What does zygomaticofacial n do
more ventral, supplies skin over zygomatic arch and lower eyelid
What are the branches of the pteryogopalatine and what do they do
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
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.
What does mandibular n do
motor: muscles of mastication
Sensory
List the motor branches of the mandibular 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
buccal - inside cheek
lingual - general and special sense of tongue
inferior alveolar - all lower teeth
mental - skin of chin
Describe the auriculotemporal n and its branches
Sensory to skin of external ear and temporal region
Branches to transverse facial n and communicating br with dorsal buccal of 7
Gives sensation to same field for which the dorsal buccal of 7 provides motor innervation
Abducent n course
Exits orbital fissure (orbitorotundum in Ru.) with CN 3, 4, and opthalmic
What does abducent n do
Supplies lateral retractor m
Facial nerve course
Origin: medulla oblongata at lateral part of trapwezoid 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
What does vestibulocochlear n (CN 8) do
Special sensory for balance and hearing
vestibulocochlear n origin
Lateral aspect of medulla oblongata:
vestibular nuclei in medulla
cochlear nuclei in medulla
vestibulocochlear n course
Never leaves the skull
from medulla oblongata tot internal acoustic meatus to petrous part of temporal bone to inner ear
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
How is accessory n unique
only cranial n that does not take part in innervation of head structures
Accessory n course
Passes through F. magnum to join medullary root and exit via jugular. foramen
What does accessory n do
Motor to omotransversarius, cleidocephalicus, trapezius, and sternocephalicus
Hypoglossal n function
motor to all muscles of tongue
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)
What nerve(s) runs here and name the foramen
Optic (CN 2), optic canal
What nerve(s) runs here and name the foramen
Oculomotor (CN 3) and Trochlear (CN 4)
orbital fissure (orbitorotundum in Ru.)
Name this nerve
Trochlear n (CN 4)
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
Name nerve and clin sig
Cornual br of infratrochlear n
Important in dehorning in small ru.
1) Infratrochlear n
2) frontal n
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
What innervates these sensory regions
1) Ophthalmic n
2) maxillary n
3) mandibular n
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
1) Infraorbital n
2) Zygomaticotemporal n
3) Zygomaticofacial n
1) Cornual br of infratrochlear n
2) cornual br of zygomaticotemporal n
3) Frontal n
What nerve(s) runs here and name the foramen
Mandibular n of Trigeminal n (CN 5),
Oval foramen (foramen lacerum in horse)
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) Auriculotemporal n
2) Mylohyoid n
3) Inferior alveolar
4) Lingual n
1) Maxillary br (CN 5)
2) Ophthalmic br (CN 5)
3) Facial nerve (CN 7)
4) Mandibular br (CN 5)
5) C2 (Dorsal branch)
Auriculopalpebral br of Facial n (CN 7)
1) Dorsal buccal br of CN 7
2) Ventral buccal br of CN 7
3) Parotid duct
4) Parotid salivary gland
5) Dorsal buccal br of CN 7
6) Ventral buccal br of CN 7
10) Parotid duct
11) Parotid salivary gland
Clin sig and function of the nerves in boxes
1) zygomatic
2) Lacrimal
3) Auriculopalpebral - motor to orbicular oculi (muscles that closes eyelid)
4) Supraorbital - sensory to upper eyelid
5) infratrochlear
3, 4 important in ocular procedures
