Lecture 2: Cranial Nerves Flashcards

1
Q

What are the four parasympathetic ganglion?

A

Cilliary

Pterygopalatine

Otic

Submandibular

Mnemonic: Cats Prefer Smart Owners

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2
Q

Simply put, where are the 12 cranial nerves located?

Use Rule of 4s

A

Cranial Nerves 1-4 are above the pons

Cranial Nerves 5-8 in the pons

Cranial Nerves 9-12 in the medulla

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3
Q

Cranial Nerve I

What is this nerve?

What is it’s origin

Fun fact about nerve

A

Olfactory Nerve

Receptors in nasal mucosa of nasal cavity

Only type of nervous tissue to regenerate

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4
Q

What is CN I’s pathway

A

Travels through the foramina in cribiform plate of ethmoid bone and synapses in the olfactory bulb.

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5
Q

What is the modality & function of CN I?

How can CN I be damaged

What happens if this nerve is damaged?

A

Special Sensory: smell/olfaction

Fracture of cribiform plate

If damaged, can cause anosmia (partial or total loss of smell) or cerebrospinal fluid rhinorrhea

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6
Q

Cranial Nerve II

What is this nerve?

What is its origin?

A

Optic Nerve

Retina of the eye

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7
Q

What is the general tract (pathway) of CN II from the brain?

A
  1. Optic nerve fibers arise from ganglion cells in retina
  2. Enters cranium via optic foramen
  3. Nerves unite at optic chiasm
  4. Synapse onto lateral geniculate nucleus of thalamus
  5. Information is forwarded to the occipital lobe
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8
Q

What is the modality & function of CN II?

What happens if this nerve is damaged?

A

Special Sensory: vision

If damaged, can cause anopsia (visual defects) & loss of pupillary constriction

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9
Q

What cranial nerves go through the superior orbital fissure?

A

CN III - Occulomotor N.

CN IV - Trochlear N.

CN V1 - Opthalmic N.

CN VI - Abducens N.

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10
Q

Cranial Nerve III

What is this nerve?

What is it’s modality?

What is its origin?

A

Oculomotor Nerve

Somatic Motor (GSE) & Visceral Motor (GVE)

Oculumotor and Edinger Westphal nuclei within mesencephalon (midbrain)

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11
Q

What is the general tract of CN III from the brain?

A
  1. Leaves cranium via superior orbital fissure and travels to eye and eyelid.
  2. PS fibers travel to ciliary ganglion
  3. Post-gang PS fibers then travel to iris and ciliary muscle.
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12
Q

What is the parasympathetic motor function of CN III?

(What muscles is it innervating?)

A

Visceral Motor Functions

  • Constricts the pupil: sphincter pupillae muscle (constrictor)
  • Contracts cilliary muscle to make the lens of the eye more spherical and relaxed (as needed for near vision and to maintain focus)

Parasympathetic: Rest, Digest, READ

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13
Q

What is the somatic motor function of CN III?

A

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
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14
Q

What happens if CN III is damaged?

A

Oculomotor (CN III) Nerve Palsy

  • Paralysis of eye muscles leading to strabismus
    • eyes are not parallel and deviated improperly
  • Ptosis (upper eleyid droop)
  • Diplopia (double vision)
  • Dilated pupil
    • Difficulty with focusing

Gaze will be down and out!!

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15
Q

Cranial Nerve IV

What is this nerve?

What is it’s modality?

What is its origin?

A

Trochlear Nerve

Somatic Motor (GSE)

Trochlear nucleus within mesencephalon (midbrain)

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16
Q

What is the general tract of CN IV?

A

Leaves cranium via superior orbital fissue and travels to superior oblique muscle

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17
Q

What is the only nerve that exits on the dorsal surface of the brainstem?

A

Trochlear Nerve (CN IV)

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18
Q

What is the function of CN IV?

What happens if this nerve is damaged?

A

Somatic Motor: Innervates Superior Oblique Muscle (depresses, internally rotates, and abducts the eye)

Paralysis of superior oblique, leading to strabismus (cross eyes)

Inability to look down when eye is adducted

Diplopia (double vision)

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19
Q

Cranial Nerve VI

What is this nerve?

What is it’s modality?

What is its origin?

A

Abducens Nerve

Somatic motor (GSE)

Pontine (abducens) nucleus in pons

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20
Q

What is the general tract of CN VI?

A

Leaves cranium through superior oribital fissue and travels to lateral retus muscle

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21
Q

What is the function of CN VI?

What happens if this nerve is damaged?

A

Somatic Motor: Innervates Lateral Rectus Muscle (abducts eye)

ABDUCENT NERVE PALSY

  1. No lateral eye movement (can’t abduct eye)
  2. diplopia (double vision)
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22
Q

Cranial Nerve V

What is this nerve?

What is its CNS origin?

A

Trigeminal Nerve

Lateral side of Pons

Derivatives of 1st pharyngeal arch

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23
Q

What are the divisions of CN V?

A

CN V1: Ophthalmic Branch of the Trigeminal Nerve

CN V2: Maxillary Branch of the Trigeminal Nerve

CN V3: Mandibular Branch of the Trigeminal Nerve

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24
Q

What is the tract of the CN V1 division?

A

Sensory fibers enter cranium via superior orbital fissue and travel to trigeminal ganglion before entering pons

superior orbital fissue -> trigeminal ganglion -> pons

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25
What is the function of CN V1?
**Sensory Afferent** Conducts sensory impulses from cornea, nose, forehead and anterior scalp
26
What is the pathway for CN V2
foramen rotundum -\> trigeminal ganglion -\> pons
27
What is the function of CN V2?
Sensory Afferent Skin of face, lower eyelid, nasal mucosa, upper lip, cheeks, maxillary teeth
28
What is the pathway for CN V3
Sensory: foramen ovale -\> trigeminal ganglion -\> pons Motor: Pons -\> foramen ovale -\> muscles
29
What is the function of CN V3?
**Sensory Afferent** * Sensory Impulses for Anterior 2/3 of the tongue (**sense not taste)** * Skin of mandible (chin), lower jaw, lower teeth; one-third from sensory fibers of auricle of ear **Visceral Efferent (Branchial Motor)** * Innervates muscles of mastiation * Innervates mylohyoid, anterior belly of digastric muscle, tensor tympani, and tensor veli palatini
30
CN V Damage
Loss of Pain & Touch sensations paraesthesia masseter and temporalis muscles do not contract Deviation of mandible to side of lesion when mouth is open Trigeminal Neuralgia (tic douloureux) produces exruciating, episodic pain that is usually restricted to the areas supplied by the maxillary and/or mandibular divisions of this nerve
31
**Cranial Nerve VII** What is this nerve? What is its origin?
Facial Nerve Nuclei within the Pons *Derivatives of 2nd Pharyngeal Arch*
32
What are the modalities of CN VII
1. Branchial Motor (Special Visceral Efferent) 2. Visceral Motor (General Visceral Efferent) 3. General Sensory (General Somatic Afferent) 4. Specail Sensory (Special Sensory Afferent)
33
What are the branches of CN VII and their function
Facial N. proper - Muscles of fascial expression, Posterior Belly of digastric M. & Stylohyoid M. Chorda Tympani N. - Innervates submandibullar and sublingual salivary glands. Receives Special Sesonsory from anterior 2/3rds of tongue Greater Petrosal N. - Innervates lacrimal, nasal & palatine glands
34
What is the pathway for CN VII Sensory Fibers
Travel from tongue via chorda tympani (branch of Facial N.) -\> enter skull -\> fibers synapse at geniculate ganglion of the Facial N.
35
CN VII Somatic Motor pathway
Leave the pons and enter the temporal through the internal acoustic meatus. Project through the temporal bone and emerge out the stylomastoid foramen to supply the musculature.
36
CN VII Parasympathetic motor pathway
PS motor fibers leave the pons, enter the internal aucoustic meatus, leave with either the **greater petrosal nerve or chorda typani nerve**, and travel to an autonomic ganglion before innervating their respective glands.
37
CN VII Branches to Muscles of Facial Expression
Posterior **A**urcicular, **T**emporal, **Z**ygomatic, **B**uccal, **M**andibular & **C**ervical branch **A** **T**iny **Z**ebra **B**it **M**y **C**heek
38
Sensory Function of VII
Taste from anterior two-thirds of tongue
39
Somatic Motor Function of VII
The 5 major motor branches innervates the muscle of fascial expression, the posterior belly of the digastric muscle, and the stylohyoid and stapedius muscle.
40
What does the parasympathetic motor function of CN VII?
Greater Petrosal - Innervates Lacrimal, Palatine & Nasal glands Chorda Tympani - Innervates Submandibular and Sublingual salivary glands
41
What CN is involved in closing the eye?
CN VII - Facial N. proper
42
What happens if CN VII is damged
Decreased tearing (dry eye) Decreased salivation (dry mouth) Loss of taste sensation to anterior 2/3 of tongue Bell Palsy/Facial Nerve Palsy: Paralyzed facial muscle, eyelid droop, sagging at corner of mouth.
43
What CN is affected in Bell's Palsy? What occurs as a result?
CN VII Inability to use facial muscles
44
Remembering CN VII functions
CN closes your eyes, tastes like pie (anteriror 2/3), makes you cry & innervates all the glands in the head except the one it goes through (parotid gland).
45
**Cranial Nerve VIII** What is this nerve? What is its modality? What is its origin?
Vestibulocochlear Nerve Special Sensory Vestibular branch - Hair cells in the vestibule of inner ear Cochlear branch - Cochlea of inner ear
46
What is the general tract of CN VIII?
Vestibular branch + cochlear branch meet then enter cranial cavity via the internal acoustic meatus and travel to junction of the pons and medulla oblongata (pontomedullary junction)
47
What is the function of CN VIII? What happens if this nerve is damaged?
Hearing - cochlear branch Balance - vestibular branch If there is damage, can lead to loss balance, nausea, vomitting, dizziness, and deafness. **Progressive unilateral hearing loss. Tinnutus (noises in ear)**
48
**Cranial Nerve IX** What is this nerve? What is its CNS origin?
Glossopharyngeal Nerve Medulla *Derivatives of 3rd pharyngeal arch*
49
CN IX Modalities
Branchial Motor (SVE) Visceral Motor (GVE) Visceral Sensory (GVA) General Sensory (GSA) Special Sensory (SA)
50
What is the function of CN IX?
1. General sensation and taste to posterior 1/3 of tongue 2. chemoreceptor fibers to the carotid bodies (detect and monitor O2 & CO2 lvls in blood going to brain) 3. Motor: Innervates stylopharyngeus (pharynx muscle) 4. Para: Innervated parotid salivary gland
51
What is the Sensory Pathway of CN IX?
Sensory fibers travel from posterior 1/3 of tongue and carotid bodies along nerve through the inferior or superior ganglion into the jugular foramen and travel to pons posterior 1/3 of tongue & carotid bodies --\> inferior or superior ganglion --\> jugular foramen --\> pons
52
CN IX Motor Pathway
Somatic motor fibers leave the cranium via jugular foramen and travel to stylopharyngeaus M.
53
CN IX Parasympathetic Pathway
PS motor fibers travel to otic ganglion and then to parotid gland
54
What is the parasympathetic function of CN IX?
Innervates parotid salivary gland
55
CN IX Damage
Reduced salivary secretion (dry mouth), loss of taste sensations to posterior 1/3 of tongue; **loss of sensation on affected side of soft palate.**
56
**Cranial Nerve X** What is this nerve? What is its CNS origin?
Vagus Nerve medulla oblongata
57
What are the modalities of CN X
Branchial Motor (SVE) Visceral Motor (GVE) Visceral Sensory (VA) General Sensory (GSA)
58
What is the general tract of CN X?
Leaves cranium via jugular foramen before traveling and branching extensively in neck, thorax and abdomen; sensory neuron cell bodies are located in the superior and inferior gangla associates with the nerve.
59
What is the Sensory function of CN X?
Visceral sensory information from pharynx, larynx, heart, lungs and most abdominal organs. General sensory information from external auditory canal, eardrum, and pharynx
60
Motor function of CN X
BM - Innervates palatoglossus (tongue M.) and most pharynx and larynx muscles VM - Innervates smooth muscles and glands of heart, lungs, pharynx, larynx, trachea, and most abdominal organs
61
What is the parasympathetic function of CN X?
Innervates smooth muscles and glands of heart, lungs, larynx, trachea, and most abdominal organs
62
If CN X is damaged, what conditions can occur?
* Larnyx issues: hoarseness or loss of voice * Difficulty Swallowing * Impared gastrointestinal system mobility * Deviation of Uvula away from the lesion
63
Which direction does the uvula deviate if there is a lesion on CN X?
_Away_ from the side of the lesion
64
**Cranial Nerve XI** What is this nerve? What is its origin?
**Spinal Accessory Nerve** cranial root - motor nuclei in medulla oblangata spinal root - motor nuclei in spinal cord
65
What is the general tract of CN XI?
Spinal root travels superiorly to enter skull through foramen magnum. There the cranial and spinal roots merge and leave the skull via jugular foramen. Once outside the skull, cranial roots splits to travel with CN X (vagus) and spinal root travels to strenoclenoidmastoid and trapezius
66
What is the function of CN XI? What happens if this nerve is damaged?
**Special Visceral Efferent (Branchial Motor)**: Cranial root - travels with CN X fibers to pharynx Spinal root - supplies SCM and Trapezius muscles If damaged, can lead to difficulty elevating shoulder **(drooping of shoulders)** or _turning head to opposite side_
67
**Cranial Nerve XII** What is this nerve? What is its origin?
**Hypoglossal Nerve** hypoglossal nucleus in medulla oblongata
68
What is the general tract of CN XII?
Leaves cranium via hypoglossal canal; travels inferior to mandible and to inferior surface of tongue.
69
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 Palatoglossus Muscle (CN X). If damaged, can lead to difficulty swallowing and speaking. If a single hypoglossal nerve is paralyzed, a protrude tongue deviates to the side of the damaged nerve. Name means "under the tongue"
70
What direction will the tongue deviate if there is a lesion of the hypoglossal nerve on one side?
_Towards_ the lesion May atrophy
71
What nucleus do the parasympathetic fibers of CN VII travel with?
Superior salivatory nucleus
72
What nucleus do the parasympathetic fibers of CN IX arise from?
Inferior Salivatory nucleus
73
The ______ provides the efferent limb of the gag reflex while the ________ provodes the afferent limb of the gag reflex
1. Vagus N. (CN X) 2. Glossopharyngeal N (CN IX)