6. Cranial Nerves Flashcards
CN12 has what components, what does it do, and what nucleus does it come from?
Hypoglossal nerve.
1 somatic motor component going to muscles of tongue
Hypoglossal nucelus
CN6 has what components, what does it do, and what nucleus does it come from?
Abducens
1 somatic motor component going to lateral rectus muscle of eye
Abducens nucleus
CN4 has what components, what does it do, and what nucleus does it come from? Fx of m. it innervates? What is so special about CN4
Trochlear n
1 somatic motor component going to superior oblique muscle (depression, intorsion)
Trochlear nucleus
Special: Innervates contralateral eye
CN11 has what components, what does it do, and what nucleus does it come from?
Spinal accessory n
1 branchial motor going to trapezius and SCM
Spinal accessory nuc
CN3 has what components, what does it do, and what nucleus does it come from?
Occulomotor n
1 somatic motor and 1 visceral motor
Somatic motor: innervate medial, inferior, superior rectus m., inferior oblique m., superior levator palpebrae m. - From occulomotor nuc
Visceral motor: innervate pupil and ciliary m - From Edinger-Westphal nuc
CN5 has what components, what does it do, and what nucleus does it come from?
Trigeminal n
1 branchial motor and 1 somatic sensory
Branchial motor: Muscles of mastication - Motor nuc of V
Somatic sensory: sensory R from face - Trigeminal sensory nuclei
CN7 has what components, what does it do, and what nucleus does it come from?
Facial n
2 motor and 2 sensory components
Brancial motor: M. of facial expression - facial motor nucleus
Visceral motor: Salivary and lacrimal glands - superior salivary nucleus
Special visceral sensory: Taste buds and project to solitary nucleus
Somatic sensory - outer ear projecting to spinal nuc of V
CN9 has what components, what does it do, and what nucleus does it come from?
Glossopharyngeal n
2 motor, 3 sensory
Branchial motor: stylopharyngeus m. - nucleus ambiguus
Visceral motor: parotid gland - inferior salivary nucleus
Special visceral sensory: taste buds and projecting to solitary nuc
Visceral sensory: pharynx, carotid body, and sinus - solitary nucleus
Somatic sensory: outer ear, pharynx, and posterior tongue - spinal nucleus of V
CN10 has what components, what does it do, and what nucleus does it come from?
Vagus
2 Motor, 3 sensory
Branchial motor: m. of pharynx and larynx - nuc ambiguus
Visceral motor: thoracic and abdominal viscera - dorsal motor nuc of X
Special visceral sensory: taste buds - solitary nuc
Visceral sensory: thoracic and abdominal viscera - solitary nuc
Somatic sensory: outer ear - spinal nuc of V
What are the three nuclei that are shared by the cranial nerves?
Solitary nucleus
Spinal nucleus of V
Nucleus ambiguus
What information is received by the solitary nucleus, which nerve(s)?
Shared by CN7,9,10. Taste info from rostral 2/3 of the tongue goes in CN7, posterior 1/3 is CN9, epiglottis is CN10
Which nucleus has fibers from CN 5, 7, 9, 10?
Spinal nucleus of 5
Which cranial nerves share nucleus ambiguus?
CN 9, CN 10
Generally speaking, what happens with a upper motor neuron lesion?
Nothing because you have contralateral innervation as well that make up for the lesion. May be weaker
Generally speaking, what happens with a lower motor neuron lesion?
See ipsilateral deficits
CN1 has what components, what does it do, and what nucleus does it come from?
Olfactory n.
Special sensory: Smell
Projects into the pyriform area B/L
CN2 has what components, what does it do, and what nucleus does it come from?
Optic n.
Special sensory: Vision
Projects to: Superior colliculus (pretectal area of midbrain), lateral geniculate nucleus (thalamus) –> visual cortex
Also to suprachiasmatic nucleus (hypothalamus)
What is the purpose of CN2 having projections to the suprachiasmatic nucleus?
For wakefulness/sleep (Circadian rhythm)
What is the pathway for how visual information comes in through the optic nerve to the visual cortex?
Signal goes through optic nerve to to lateral geniculate nucleus in thalamus –> Meyer’s loop –> optic radiations –> visual cortex
What are the muscles and fx of those muscles that are innervated by CN3?
Pupillary muscle
Medial rectus - adduction
Inferior rectus - depression and extortion
Superior rectus - elevation and intortion
Inferior oblique - elevation and extortion
Which opening does CN3 transverse through to get to its target organ?
Superior orbital fissure
How does accommodation work?
Ciliary body contracts –> suspensory ligs loosen –> lens gets thicker –> NEAR VISION
Ciliary body relaxes –> suspensory ligs tighten –> lens gets stretched thin –> FAR VISION
Pupillary reflex
Shine light in one eye, goes through optic nerve to superior colliculus B/L –> interneuron to edinger-westphal –> occulomotor PNS branch to ciliary ganglion –> pupillary constriction
What happens if you damage the right optic nerve and shine light in right eye? Shine light in left eye?
No pupil reflex in either eye if you shine light in right eye.
Shine light in left eye, pupillary reflex in tact for both eyes
What happens if you damage the right occulomotor nerve and shine light in right eye? Shine light in left eye?
Shine light in right eye: Left eye constricts, right eye doesn’t
Shine light in left eye: Left eye constricts, right eye doesn’t
The facial motor nucleus wraps around which other nucleus?
Abducens nucleus
Conjugate gaze nerves and pathway
CN3, CN6
Starts in superior colliculus –> PPRF (lateral gaze center)
PPRF sends projects to two nuclei:
1) abducens nuc. - eye abduction
2) Occulomotor nuc - eye adduction through MLF (medial longitudinal fasiculus)
Lesion in MLF would cause what?
Imaired conugate gaze (doesnt get to occulomotor nucleus)
What is internuclear opthalmoplegia
Paresis of adduction in one eye and nystagmus in contralateral abducting eye
What are the three branches of the trigeminal nerve?
V1 - opthalmic (sensory)
v2 - maxillary (sensory)
v3 - mandibular (sensory and motor)
What is the pathway for afferent sensory information for trigeminal nerve to the sensory cortex?
Signal passes through ganglion to get to brainstem spinal nucleus of V –> decussates and synapses onto thalamus –> goes to sensory cortex
What nerve is responsible for the bite reflex?
Trigeminal V3
Pathway to induce secretions from the submandibular and sublingual glands. Which CN?
CN7
Superior salivary nucleus –> submandibular and ptergopalatine nuclei –> secretions from submandibular and sublingual glands
CN7 relays touch and pain sensation. Which areas?
Concha of ear
External auditory meatus
External surface of tympanic membrane
Skin behind ear
What is the difference in facial expression muscles’ innervation above the eye and below the eye?
Above eye: inn. by both upper and lower MN
Below eye: inn. by contralateral side
What happens if upper motor nuclei lesion of facial motor nucleus?
Not much difference, slight dropping of corner of mouth.
What happens if lower motor nuclei lesion of facial motor nucleus?
Drooping of lower portion of face
What are the nuclei involved in CN8 and fx.
Vestibular nuc (balance) Dorsal cochlear (contralateral, hearing) Ventral cochlear (B/L) hearing
Solitary nucleus receives which inputs?
CN7 - taste anterior 2/3
CN9 - taste posterior 1/3
CN10 - taste epiglottis
CN9 - carotid body has chemoreceptor (rate of respiration) that monitors O2, CO2, and acidity/alkalinity (at break between internal and external carotid arteries)
Carotid sinus has baroreceptors that monitor blood pressure
CN10- aortic bodies - chemoR
aortic arch - baroR
Which nerves are tested with the gag reflex?
CN9, CN10
Fx of vagus on heart, lungs, GI
Cardiac: slow HR
Resp: bronchiolar secretions and bronchoconstriction in lungs
GI: stimulate secretion and motility
Gag reflex
CN9 is sensory
Vagus is motor
Sensory input of something in back of mouth:
- closure of epiglottis
- protrusion of tongue (hypoglossal n)
- constrict pharyngeal m
CN11 innervates which two muscles? C/L or ipsilateral?
Trapezius - contralateral
SCM - ipsilateral
CN12 inn which muscle?
genioglossal
UMN lesion of CN12
Tongue deviates to contralateral side
LMN lesion of CN12
Tongue deviates to ipsilateral side
