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What is formed at 6 weeks of embryological development in respect to CN?
3 motor columns and 3 sensory columns that span through the brainstem.
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What is general somatic sensory column
- GSA
- Sensation to faces, sinus, and meninges
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What is visceral sensory column?
- GVA and SVA
- Smell, taste, and input for CV control
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What is Special somatic sensory column?
- SSA
- Other special senses such as hearing, vision
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What is somatic motor column?
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What is the parasympathetic column?
- GVE
- head, neck and thoracoabdominal viscerae
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What is th branchial motor column?
- SVE
- Muscle of mastication, face, stern/trap, pharynx, larynx
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What is the course of the Olfactor Nerve
Olfactory nerve -> Cribiform plate -> olfactory bulbs -> olfactory tracts
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What is anosmia?
Olfactory loss. bilateral condition is rare bu can occur in people with PD or AD, or TBI w/ frontal lobe
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What fiber type is the olfactory nerve?
SVA
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What is the course of the optic nerve?
Retina -> bipolar / ganglion neurons -> optic chiasm -> optic tract -> LAT geniculate nucleus -> optic radiation -> visual cortex
(from orbit into the optic canal)
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What fiber type is the optic nerve?
SSA
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What is the point of origin(s) and target organ(s) of CN III?
- From Midbrain; interpeduncular fossa to the:
- SUP, INF, MED rectus, and INF oblique.
Parasympathetic fibers supply the pupillary constrictor and ciliary muscles.
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What is the point of origin(s) and target organ(s) of CN IV?
Posterior midbrain --> Superior oblique
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What is the point of origin(s) and target organ(s) of CN VI?
Pontomedullary junction --> Lateral Rectus
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What are the fiber types for CN III?
- GVE for paraympathetic from the Edinger - Westphal nucleus and go to the ciliary ganglion to the ciliary muscles and pupillary constrictor muscles
- GSE for eye movements
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What fiber types and CN(s) are responsible for eye movement?
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How do the eye muscles affect an "Adducted" eye (Medially rotated)
- SUP rectus = intorsion
- INF rectus = extorsion
- SUP oblique = depression
- INF obliqu = elevation
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How do the eye muscles affect an "ABDucted" eye (Laterally rotated)?
- SUP rectus = Elevation
- INF rectus = depression
- SUP oblique = intorsion
- INF obliqu = extorsion
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What is the course of the trigeminal nerve?
Arises from mid pons -> enters Meckel's cave (fossa), where the trigeminal (semilunar) ganglion is.
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What are the branches of the trigeminal nerve?
- V1 - Opthalamic (GSA)
- V2 - Maxillary (GSA)
- V3 - Mandibular (GSA and SVE)
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What is the fiber type and target organ of V1?
- Skin sensation of nose, orbits, forehead, nasal sinus, cornea
- GSA
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What is the fiber type and target organ of V2?
- skin sensation of upper lip, cheeks, temples
- GSA
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What is the fiber type and target organ of V3?
- GSA - Skin sensation of mandible, TMJ, ear, EXT auditory canal
- SVE - Muscles of mastication, tensor tympanis and palatini mm, ANT belly of digastric, and mlohyoid mm.
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What is the course of the Facial nerve? (CNVII)
emerges from the cerebeloopontine angle -> internal auditory meatus -> auditory canal, the genu (geniculate ganglion, -> facial canal -> exits through the stylomastoid foramen. Goes through the parotid gland (but does not supply it)
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What are the division of the facial nerve?
- Temporal
- zygomatic
- buccal
- mandibular
- cervical branches
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What kind of fibers and what is the function of the facial nerve?
- GSA: Sensation of the EXT auditory meatus
- SVA: Taste of ANT 2/3 of tongue
- GVE: Parasympathetic innervation to lacrimal, sublingual and submandibular salivary glands
- SVE: muscles of facial expression, stapedius, and POST belly of digastric
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What are the 2 branches off of the facial nerve?
- Greater petrosal nerve
- chorda tympani
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Where does the greater petrosal nerve go?
From the facial nerve --> pterygopalatine ganglion --> lacrimal gland
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Where does the chorda tympani go?
Branches from the facial --> joins the lingual nerve (from V3) --> submandibular ganglion --> submandibular and sublingual salivary glands
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How would an upper motor lesion of the facial nerve present?
spare contralateral forehead, affects lower face. Accompanied by upper limb mixed deficits.
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How would a lower motor neuron lesion of the facial nerve present
Affects the whole ipsilateral face. i.e. bell's palsy
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What is Bell's palsy?
- LMN facial nerve.
- unilateral facial muscle weakness
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What causes the corneal reflex?
- Afferent limb: V1;
- Efferent limb: VII.
- Action- stroke cornea with a cotton swab; reflex causes bilateral blinking.
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What is the couse of CN VIII (Vestibulocochlear)?
- Emerges from cerebellopontine angle enters INT auditory meatus along with CN VII travels in auditory canal.
- Terminates at the vestibular organs and cochlea
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What type of fiber(s) does CN VIII contain?
SSA
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What does the CN VIII (Vestibulocochlear) nerve do?
Mediates auditory input and vestibular input for balance.
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What is the course of CN IX (Glossopharyngeal)
Emerges from the ventrolateral medulla and exits skull via the jugular foramen
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What are the fibers and function of the CN IX?
- GSA - sensation from middle ear, region near the EXT auditory meatus, pharynx, and POST 1/3 of tongue
- GVA - Chemo/baroreceptors of carotid body
- SVA - taste from POST 1/3 of tongue
- GVE - parotid glad
- SVE - styopharyngeus muscle (gag reflex)
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What are is the cell bodies for the GVA CN IX?
Caudal nucleus solitarius --> chemoreceptors of carotid body
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What are is the cell bodies for the SVA CN IX?
Rostral nucleus solitarius - taste POST 1/3 tongue
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What are is the cell bodies for the GVE CN IX?
Inferior salivatory nucleus -> otic ganglion -> parotid gland (parasympathetic innervation)
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What are is the cell bodies for the SVE CN IX?
Branchila motor from nucleus ambiguus -> supply the stylopharyngeus mm
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What is the course of CN X (Vagus)?
Exits the ventrolateral medulla, post-olivary sulcus. Exits skull through jugular foramen.
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What are the fibers and nuclei of the Vagus nerve?
- GSA
- Caudal nucleus solitarius --> GVA to chemo/baroreceptors
- Rostral nucleus solitarius --> SVA fibers carrying taste from epiglottis
- Nucleus ambiguus --> SVE pharyngeal and laryngeal mm, upper esophagus (gag and swallow)
- Dorsal motor nucleus - GVE viscerla organs does to the transverse colon
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What are the actions of the GSA fibers from the vagus nerve?
sensation from pharynx, POST meninges, part of EXT auditory meatus
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What are the actions of the CN X influence on the caudal nucleus solitarius?
GVA to chemo/baroreceptors
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What are the actions of the CN X influence on the rostral nucleus solitarius
SVA fibers carrying tast from the ipglottis
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What are the actions of the CN X influence on the Nucleus ambiguus?
SVE - branchial motor fibers to the parygneal and laryngeal mm and upper esspophagus (swallowing and gag reflex)
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What are the actions of the CN X influence on the Dorsal motor nucleus
- Forms vagal trigone. - GVE
- parasympathetic innvervation to all visceral organs down to the transverse colon
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What is the course of the CN XI (accessory)
Spinal accessory nucleus --> emerges from the medulla, post olivary and upper 5 cervical levels. Exits the juglar foramen.
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What are the fiber type(s) and targets CN XI (accessory)?
- Trapezius
- Sternocleidomastoid.
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What is the course of CN XII (hypoglossal)?
Hypoglossal nucleus in the medulla -> exits PRE-olivary -> goes through the hypoglossal foramen -> somatic motor innervation to intrinsic and extrinsic muscles of the tongue
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What are the fiber type(s) and action of CN XII?
GSE to intrinsic and extrinsic muscles of the tongue
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What is dysartria and what CN(s) are involved?
- abnormal articulation of speech
- CN V, VII, IX, X, and XII
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What is dysphagia and what CN(s) are involved?
- impaired swallowing.
- Lesions of CN IX, X and XII
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What is the only CN that emerges on the dorsal part of the brainstem?
CN IV
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What CN(s) decussate?
CN IV
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What CN emerge post olivary?
9, 10, 11
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What CN emerge pre-olivary?
12
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What CN(s) carry parasympathetic fibers?
CN 3, 7, 9, 10
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What does the motor and sensory to the face?
- Sensory - CN V
- Motor - CN VII
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What CN(s) do taste?
- VII (ANT 2/3)
- IX (POST 1/3)
- X (epiglottis)
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What are the CN(s) that move the eye and what foramen do they exit?
- occulomotor
- trochlear
- abducens
- ALL THROUGH THE SUPERIOR OCCIPITAL FISSURE
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