Lecture 6 Flashcards
study slide 4
ye
study slide 6
ye
what is CN I?
olfactory nerve
what is CN II?
optic nerve
what is CN III and its functions?
oculomotor nerve
- motor: levator palpebrae sup, all extraocular muscles (except SO and LR),
- parasymp. motor: pupi constriction and lens movement/ciliary muscles
what is CN VI?
trochlear nerve; purpose is for SO
what is CN V?
trigeminal nerve
- -sensation (touch, pain, temp, vibrations, proprioception) for the face (territories of V1, V2, and V3), mouth, ant 2/3s of the tongue, nasal sinuses, and meninges
- -pain is also supratenorial dura mater (above cerebellum)
-inns MOMs and tensor tympani muscle
what is CN VI?
abducens nerve– inns LR
what is CN VII?
facial nerve
- motor: muscles of facial expression, stapedius muscle, and part of digastric muscles
- parasymp: all glands but parotid
- special sensory: ant 2/3s of tongue taste
- sensation from small region near external auditory meatus
what is CN VIII?
vestibulocochlear nerve
what is CN IX?
glossopharyngeal nerve
–branchial motor: stylopharyngeus muscle
- parasymp: parotid gland
- general somatic sensory: -sensation from middle ear, region near EAM, pharynx, and post 1/3 of tongue
visceral sensory (special) = taste from post 1/3 of tongue
visceral sensory = chemo- and baroreceptors of carotid body
what is CN X?
vagus nerve
– branchial motor: pharyngeal muscles (swallowing) and laryngeal = voice
–parasymp = heart, lungs, and G tract down to splenic flexure
–general somatic sensory: sensation from pharynx, meninges, and a small region near EAM
visceral sensory (special): taste from epiglottis and pharynx
–visceral sensory (general): chemo and baroreceptors of the aortic arch
what is CN XI?
Accessory nerve
what is CN XII?
hypoglossal nerve, for intrinsic muscles of the tongue
describe the locations of the cranial nerves nuclei
CN I and II –> outside of the brainstain
CN III, IV,–> in the midbrain
CN V, VI, VII, VIII –> in the pons
CN IX, X, XI, XII –> in the midbrain
describe conjugate eye movements on the cortical level
the visual cortex connects to the parieto-occipito-temporal area (ipsilateral pursuit and contralateral eye movements)
it also connects to the frontal eye fields–> contralateral saccades/scanning
the posterior eye field controls smooth pursuit
why is conjugate eye movement important?
keeps vision in focus
describe trigeminal neuralgia
- most often in the V2 or V3 region of face
- recurrent episodes of brief but severe pain
- easily triggered by light stimulus
what are the CNs derived from ectoderm?
CN I, II, VIII
-purely sensory
what are the CNs derived from neural crest?
V, VII, IX, X, XI
–from branchial arches, mixed (sensory and motor)
–special motor
what are the CNs derived from mesoderm?
CN III, IV, VI, and XII
–somatic motor
what do we mean by branchiomeric?
neural crest derived CNs (V, VII, IX, X, XI)
describe the defecits seen in CN III lesions
-motor: ptosis (droopy eyelid); diplopia (double vision); impaired eye movements
- visceral motor deficits/parasym:
- -pupil dilation (mydriasis), (impaired pupillary light reflex). impaired accomodation
describe the deficits seen in CN IV lesion
- diplopia
- impaired eye movements
describe trigeminal nerve dysfunctin
-impaired chewing
somatosensory deficits (head)
describe facial nerve dysfunction
som. motor: – impaired facial expression
vis motor: - impaired salivation, earing
somat. sensory deficits (ext ear)
special sensory–>impaired aste
CN VIII dysfunctions?
-nausea
-dizziness
-nystagmus
impaired hearing
what are vagus nerve dysfunctions?
somatic motor dysfunction
- hoarseness
- difficulty swallowing (may see pocketing)
- impaired articulation
- impaired gag reflex
visceral motor dysfunction
- impaired peristalsis
- hypertension (impaired baroreflex)
- resp defecits
-somatosensory deficits (external ear)
impaired taste
what are glossopharyngeal nerve dysfunctions?
somatic sensory/motor: impaired gag reflex
visceral motor dysf.: impaired salivation (xerostomia) and hypertension (impaired baroreflex)
somatosensory dysf.: somatsens. deficits in external ear and impaired sensation in throat
special sense dysf: impaired taste (post 1/3 of tongue)
describe accessory nerve dysfunction
-drooping shoulder and impaired head turning
describe hypoglossal nerve dysfunction
-impaired tongue movements
- -if there is a UMN lesion, the tongue will deviate AWAY from the affected side (side of lesion)–contralateral
- if it is an LMN lesion, the tongue will deviate ipsilateral (to the side of the lesion)
-impaired articulation
frontal eye fields control saccades–>high speed, voluntary movements; contralateral
ye
posterior eye field (in parietal lobe) is for smooth pursuit; low speed smooth movement heavily influenced by visual input; IPSILATERAL
ye
what is the MLF?
medial longitudinal fasciculus; is ensures that eye muscles work together to keep the visual image centred on the FOVEA
–coordinates activity of CN III, IV, and VI
–e.g. both eyes move to right, so the lateral rectus of the right eye is activated, but not the lat rec of left
for CONJUGATE EYE MOVEMENT
study slide 44
ye
describe right oculomotor nerve palsy
-ptosis–droopy eyelid
–unopposed SO and LR–> eye looking down and out
describe right trochlear nerve palsy
right eye is looking up and out (lose intorsion and depression of eye)
people will turn their head to focus on you
describe CN VI nerve palsy (right)
right eye –>try to look right, but right LR cannot pull eye outwards (cannot abduct)
–diplopia
trigeminal nerve fibres enter the CNS at the level of the brainstem (midbrain, pons, medulla)
ye
describe where all the sensory nuclei of CN V are found in the brainstem
–the MESENCEPHALIC (midbrain-located) nuclei–mostly convey proprioceptive info, and sensory cell-bodies located in the nucleus
–in the pons, the main sensory nuclei (the primary neuron of the trigeminal nuclei) are the GSA fibres conveying discriminative touch into the nucleus
–in the medulla, the DESCENDNG spinal nuclei are found–mayb convey temp and pain info to sensory bodies in the trigeminal nucleus; they also receive fibres from VII, IX, and X for visceral afferents of larynx and pharynx
what is infratenorial pain conveyed by?
-CN X, XI, and first three cervical nerves
what are corticobulbar pathways?
motor pathways of cranial nerves which parallel the corticospinal tract
–most commonly they refer to motor pathways from CN V, VII, IX, some of X, and XII, and they derive from the cortex (UMNs) and synapse on LMNs
study slide 58
ye
UMN lesions cause weakness (paresis) on the CONTRALATERAL bottom 2/3s of the face as the LMNs only receive unilateral inn, while LMN lesions causes IPSILATERAL weakness on one side of the face (forehead not spared)- STUDY SLIDE 59
ye
cranial nerve 12–inn the intrinsic muscles of the tongue, and if the right UMN is damaged, there is hemiparesis on the CONTRALATERAL (left) side, and if the LMN is damaged, it is ipsilateral
ye
describe the pupillary light reflex
CN II receives light input unilaterally–synapse on the edinger-westphal nucleus (in the midbrain) which send BILATERAL autonomic output via CN III to BOTH eyes
does not require cortical input or extraocular muscles
describe the corneal reflex
irritation on one cornea–>unilateral input via CN V; synapse to CN VII which has BILATERAL output–> and causes both eyes to blink
study slide 66
ye
describe the gag reflex
sensory via glossopharyngeal if the soft palate or post pharynx is touched (back of tongue?) to the medulla –> to vagus–> vagus causes palate elevation and contraction of pharyngeal muscles
what is the cerebellopontine angle?
the region where, if a lesion occurs there, the person will xperience dizziness and nausea (lateral, vestibulocochlear nerve located)
