What is the general tract of CN IV?
- Exit dorsal surface of midbrain and pierce dura mater at margin of entorium cerebelli
- Run in lateral wall of cavernous sinus
- Enters orbit via superior orbital fissure
Cranial Nerve II
What is this nerve?
What is its CNS origin?
What is its distribution?
Optic Nerve
Diencephalon
Retina of eye
What is the general tract of CN X?
- Emerges from medulla
- Exit cranium through jugular foramen
Cranial Nerve IV
What is this nerve?
What is its CNS origin?
Trochlear Nerve
Midbrain: Pontine (Abducens) Nucleus
What presents first if CN III is compressed by an aneurysm?
Problems with parasympathetic division
Horner’s syndrome symptoms
What is the general tract of CN VII?
- Emerges from the pontine-medullary jxn
- Cross posterior cranial fossa to exit skull via internal acoustic meatus
- Run in facial canal and exit via stylomastoid foramen
- Pass through the parotid gland
What opening does the CN V2 exit from?
Foramen rotundum
What CN is affected in Bell’s Palsy?
What occurs as a result?
CN VII
Inability to use facial muscles
Cranial Nerve I
What is this nerve?
What is its CNS origin?
What is its distribution?
Olfactory Nerve
Telencephalon
Olfactory mucosa of nose
What happens if CN III is damaged?
- Ptosis (upper eleyid droop)
- Paralysis of eye muscles leading to strabismus
- eyes are not parallel and deviated properly
- Diplopia (double vision)
- Difficulty with focus
- Dilated pupil
Gaze will be down and out!!
What is the general tract of CN XII?
- Emerges from the medulla
- Exits skull via hypoglossal canal
- Travels with cervical plexus
- Cross occipital A.
- Enter oral cavity
What is the function of CN V2?
Sensory Afferent
Skin of face, lower eyelid, cheek, upper lip, maxillary teeth, mucosa of nose, maxillary sinus
What are the divisions of CN V?
CN V1: Ophthalmic Branch of the Trigeminal Nerve
CN V2: Maxillary Branch of the Trigeminal Nerve
CN V3: Mandibular Branch of the Trigeminal Nerve
What is the function of CN XII?
What happens if this nerve is damaged?
Somatic Efferent: Supplies all intrinsic and extrensic muscles of the tongue except Palaoglossus Muscle.
If damaged, can lead to difficulty swallowing and speaking.
Cranial Nerve III
What is this nerve?
What is its CNS origin?
Oculomotor Nerve
Midbrain/Mesencephalon: Oculumotor and Edinger Westphal nuclei
Cranial Nerve IX
What is this nerve?
What is its CNS origin?
Glossopharyngeal Nerve
Medulla
Derivatives of 3rd pharyngeal arch
What is the function of CN I?
What happens if this nerve is damaged?
Special Sensory: smell/olfaction
If damaged, can cause anosmia
Simply put, where are the 12 cranial nerves located?
Use Rule of 4s
Cranial Nerves 1-4 are above the pons
Cranial Nerves 5-8 in the pons
Cranial Nerves 9-12 in the medulla
What is the function of CN VII?
Special Visceral Efferent (Branchial Motor)
- Innervates Stapedius muscle (in ear)
- Innervates Stylohyoid, Posterior belly of Digastric Muscle
- Innervates muscles of facial expression
General Visceral Efferent
- Innervates lacrimal, submandibular, and sublingual glands
- Innervates mucous membrane of nose
- Innervates hard and soft palates
General Sensory Afferent
- Skin of concha of auricle, small patch behind ear
- Helps CN V3 with acoutsti meatus and external tympanic membrane
Special Sensory Afferent
- Senses taste from anterior ⅔ of tongue
- CN V3 does sensation!
- Senses taste from hard and soft palates
What is the function of CN VIII?
What happens if this nerve is damaged?
Special Sensory:
- Cochlea: Auditory Information
- Semicircular Canals: Balance Information
If there is damage, can lead to loss balance, nausea, vomitting, dizziness, and deafness
What direction will the tongue deviate if there is a lesion of the hypoglossal nerve on one side?
Towards the lesion
May atrophy
Cranial Nerve V
What is this nerve?
What is its CNS origin?
Trigeminal Nerve
Pons
Derivatives of 1st pharyngeal arch
Cranial Nerve VIII
What is this nerve?
What is its CNS origin?
What is its distribution?
Vestibulocochlear Nerve
Pontine Medullary Junction
Internal ear
Cranial Nerve VII
What is this nerve?
What is its CNS origin?
Facial Nerve
Pons
Derivatives of 2nd Pharyngeal Arch
What are the four parasympathetic ganglion?
Cilliary
Pterygopalatine
Otic
Submandibular
What CN is involved in closing the eye?
CN VII - Facial N.
What is the general tract of CN VI?
- Emerge from brainstem at pontine-medullary junction
- Traverse pontine cistern and pierce dura covering the clivus
- Run in cavernous sinus near Internal Carotid A.
- Enters orbit via superior orbital fissure
What is the tract of the CN V1 division?
Trigeminal cave => Cavernous sinus => Superior orbital fissure => orbit
What is the general tract of CNII from the brain?
- Optic nerve fibers arise from ganglion cells in retina
- Enters cranium via optic foramen
- Nerves unite at optic chiasm
- Synapse onto lateral geniculate bodies of thalamus
What does the parasympathetic motor function of CN VII?
Facial Nerve
-Innervates lacrimal gland of the eye, submandibular and sublingual salivary gland
If CN X is damaged, what conditions can occur?
- Larnyx issues: hoarseness or loss of voice
- Difficulty Swallowing
What does the parasympathetic motor function of CN X?
Vagus Nerve
-Innervates smooth muscles and glands of heart, lungs, larynx, trachea, and most abdominal organs
What does the parasympathetic motor function of CN IX?
Glossopharyngeal Nerve
-Innervates parotid salivary gland
Where is CN I located?
Where does it synapse onto?
Olfactory organ through cribiform plate to synapse onto Olfactory bulb
What is the function of CN VI?
What happens if this nerve is damaged?
Somatic Motor: Lateral Rectus Muscle (abducts eye)
If damaged, can lead to paralysis of lateral eye movements and diplopia
What nucleus do the parasympathetic fibers of CN IX arise from?
Inferior Salivatory nucleus
What cranial nerves go through the superior orbital fissure?
CN III, IV, V1, VI
Cranial Nerve VI
What is this nerve?
What is its CNS origin?
Abducens Nerve
Pontine Medullary Junction
What is the function of CN XI?
What happens if this nerve is damaged?
Special Visceral Efferent (Branchial Motor): Supplies SCM and Trapezius muscles
If damaged, can lead to difficulty elevation shoulder or turning head to opposite side
Cranial Nerve X
What is this nerve?
What is its CNS origin?
What is its distribution?
Vagus Nerve
Medulla/Myelencephalon
Derivatives of the 4th pharyngeal arch
What is the function of CN IV?
What happens if this nerve is damaged?
Somatic Motor: Innervates Superior Oblique Muscle (depresses, internally rotates, and abducts the eye)
If damaged, can lead to limited downard movement of eye, strabismus, and diplopia
What is the function of CN II?
What happens if this nerve is damaged?
Special Sensory: vision
If damaged, can cause anopsia (visual defects)
What is the sympathetic motor function of CN III?
(What muscles is it innervating?)
Somatic Motor Functions
- Innervates intrinsic eye muscle: Elevates eyelid
- Levator Palpebrae Superioris Muscle
- Innervates extrinsic eye muscle: Move eyeball
- Superior Rectus Muscle
- Medial Rectus Muscle
- Inferior Rectus Muscle
- Inferior Oblique Muscle
What is the function of CN X?
Special Visceral Efferent (Branchial Motor)
- Innervates most of the striated muscles of pharynx, tongue, and larnyx
General Visceral Efferent
- Innervates smooth muscles and glands of pharynx, larynx, thoracic and abdominal viscera
Visceral Sensory Afferent
- Carries sensation from larynx, pharynx, esophagus, thoracic and abdominal viscera
- Sensation from stretch receptors and chemoreceptors of aortic arch
General Sensory Afferent
- Sensation from skin at back of ear and external acoustic meatus
- Sensation from external surface of tympanic membrane and pharyx
*
What is the general tract of CN XI?
- Emerges from the spinal cord
- Enters cranium through foramen magnum
- Exit skull through jugular foramen
What is the general tract of CN IX?
- Emerges from medulla
- Exit cranium through jugular foramen
- Pass b/w superior and middle pharyngeal constrictors
- Enter oral cavity
What is the function of CN V1?
Sensory Afferent
Sensation to cornea, skin of forehead and scalp, upper eyelid, the bridge to the point of nose, and nasal cavity
What is the only nerve that exits on the dorsal surface of the brainstem?
Trochlear Nerve (CN IV)
What is the function of CN V3?
Sensory Afferent
- Anterior 2/3 of the tongue
- Skin of mandible, lower lip, mandibular teeth, TMJ joint, part of oral mucosa
Visceral Efferent (Branchial Motor)
- Innervates muscles of mastiation
- Innervates mylohyoid, anterior belly of digastric muscle, tensor tympani, and tensor veli palatini
Which direction does the uvula deviate if there is a lesion on CN X?
Away from the side of the lesion
What opening does the CN V3 Mandibular exit from?
Foramen Ovale
What is the parasympathetic motor function of CN III?
(What muscles is it innervating?)
Visceral Motor Functions
- Innervates sphincter pupillae muscle (constrictor)
- Contracts cilliary muscle to make muscle more round and relaxed (good with near vision)
What is the function of CN IX?
Special Visceral Efferent (Branchial Motor)
- Innervates stylopharyngeus muscle
General Visceral Efferent
- Innervates otic ganglion: stimulates parotid gland
Visceral Sensory Afferent
- Carries sensation from carotid body and sinus
General Sensory Afferent
- Sensation to posterior third of tongue
- Sensation to skin of external ear and internal surface of tympanic membrane
Special Sensory Afferent
- Senses taste from posterior third of tongue
Cranial Nerve XI
What is this nerve?
What is its CNS origin?
What is its distribution?
Spinal Accessory Nerve
Superior Spinal Cord
Superficial layer of neck
What nucleus do the parasympathetic fibers of CN VII travel with?
Superior salivatory nucleus
What is the general tract of CN VIII?
- Enter skull via interal acoustic meatus
- Enter brainstem on pontine-medullary jxn
- Vestibular - innervate utricle and saccule; Cochlear innervates cochlea
Cranial Nerve XII
What is this nerve?
What is its CNS origin?
What is its distribution?
Hypoglossal Nerve
Medulla/Myelencephalon
Muscles of tongue
What is the general tract of CN III from the brain?
- Exits midbrain through dura lateral to diaphragma sellae
- Runs in lateral wall of cavernous sinus
- Enters through superior orbital fissure into orbit
