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.
What is general somatic sensory column
- Sensation to faces, sinus, and meninges
What is visceral sensory column?
- GVA and SVA
- Smell, taste, and input for CV control
What is Special somatic sensory column?
- Other special senses such as hearing, vision
What is somatic motor column?
What is the parasympathetic column?
- head, neck and thoracoabdominal viscerae
What is th branchial motor column?
- Muscle of mastication, face, stern/trap, pharynx, larynx
What is the course of the Olfactor Nerve
Olfactory nerve -> Cribiform plate -> olfactory bulbs -> olfactory tracts
What is anosmia?
Olfactory loss. bilateral condition is rare bu can occur in people with PD or AD, or TBI w/ frontal lobe
What fiber type is the olfactory nerve?
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)
What fiber type is the optic nerve?
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.
What is the point of origin(s) and target organ(s) of CN IV?
Posterior midbrain --> Superior oblique
What is the point of origin(s) and target organ(s) of CN VI?
Pontomedullary junction --> Lateral Rectus
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
What fiber types and CN(s) are responsible for eye movement?
How do the eye muscles affect an "Adducted" eye (Medially rotated)
- SUP rectus = intorsion
- INF rectus = extorsion
- SUP oblique = depression
- INF obliqu = elevation
How do the eye muscles affect an "ABDucted" eye (Laterally rotated)?
- SUP rectus = Elevation
- INF rectus = depression
- SUP oblique = intorsion
- INF obliqu = extorsion
What is the course of the trigeminal nerve?
Arises from mid pons -> enters Meckel's cave (fossa), where the trigeminal (semilunar) ganglion is.
What are the branches of the trigeminal nerve?
- V1 - Opthalamic (GSA)
- V2 - Maxillary (GSA)
- V3 - Mandibular (GSA and SVE)
What is the fiber type and target organ of V1?
- Skin sensation of nose, orbits, forehead, nasal sinus, cornea
What is the fiber type and target organ of V2?
- skin sensation of upper lip, cheeks, temples
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.
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)
What are the division of the facial nerve?
- cervical branches
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
What are the 2 branches off of the facial nerve?
- Greater petrosal nerve
- chorda tympani
Where does the greater petrosal nerve go?
From the facial nerve --> pterygopalatine ganglion --> lacrimal gland
Where does the chorda tympani go?
Branches from the facial --> joins the lingual nerve (from V3) --> submandibular ganglion --> submandibular and sublingual salivary glands
How would an upper motor lesion of the facial nerve present?
spare contralateral forehead, affects lower face. Accompanied by upper limb mixed deficits.
How would a lower motor neuron lesion of the facial nerve present
Affects the whole ipsilateral face. i.e. bell's palsy
What is Bell's palsy?
- LMN facial nerve.
- unilateral facial muscle weakness
What causes the corneal reflex?
- Afferent limb: V1;
- Efferent limb: VII.
- Action- stroke cornea with a cotton swab; reflex causes bilateral blinking.
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
What type of fiber(s) does CN VIII contain?
What does the CN VIII (Vestibulocochlear) nerve do?
Mediates auditory input and vestibular input for balance.
What is the course of CN IX (Glossopharyngeal)
Emerges from the ventrolateral medulla and exits skull via the jugular foramen
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)
What are is the cell bodies for the GVA CN IX?
Caudal nucleus solitarius --> chemoreceptors of carotid body
What are is the cell bodies for the SVA CN IX?
Rostral nucleus solitarius - taste POST 1/3 tongue
What are is the cell bodies for the GVE CN IX?
Inferior salivatory nucleus -> otic ganglion -> parotid gland (parasympathetic innervation)
What are is the cell bodies for the SVE CN IX?
Branchila motor from nucleus ambiguus -> supply the stylopharyngeus mm
What is the course of CN X (Vagus)?
Exits the ventrolateral medulla, post-olivary sulcus. Exits skull through jugular foramen.
What are the fibers and nuclei of the Vagus nerve?
- 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
What are the actions of the GSA fibers from the vagus nerve?
sensation from pharynx, POST meninges, part of EXT auditory meatus
What are the actions of the CN X influence on the caudal nucleus solitarius?
GVA to chemo/baroreceptors
What are the actions of the CN X influence on the rostral nucleus solitarius
SVA fibers carrying tast from the ipglottis
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)
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
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.
What are the fiber type(s) and targets CN XI (accessory)?
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
What are the fiber type(s) and action of CN XII?
GSE to intrinsic and extrinsic muscles of the tongue
What is dysartria and what CN(s) are involved?
- abnormal articulation of speech
- CN V, VII, IX, X, and XII
What is dysphagia and what CN(s) are involved?
- impaired swallowing.
- Lesions of CN IX, X and XII
What is the only CN that emerges on the dorsal part of the brainstem?
What CN(s) decussate?
What CN emerge post olivary?
9, 10, 11
What CN emerge pre-olivary?
What CN(s) carry parasympathetic fibers?
CN 3, 7, 9, 10
What does the motor and sensory to the face?
- Sensory - CN V
- Motor - CN VII
What CN(s) do taste?
- VII (ANT 2/3)
- IX (POST 1/3)
- X (epiglottis)
What are the CN(s) that move the eye and what foramen do they exit?
- ALL THROUGH THE SUPERIOR OCCIPITAL FISSURE