9/12 Brainstem2 - Rasin Flashcards Preview

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Flashcards in 9/12 Brainstem2 - Rasin Deck (13):



triangle associated

motor components and fx

sensory components and fx

mixed components (efferent coming out, afferents coming in)

dorsal view: can see vagal triangle lateral to hypoglossal triangle



2 efferent motor components

1. GVE (general visceral efferent)preganglionic parasympathetic to...

  • ganglia for heart, lungs, GI up to the splenic flexure
    • Q: what about below???
    • A: sacral parasympathetics! (S2-S4)

2. SVE (special visceral efferent) : muscles of branchial arches

  • pharnyngeal muscles (swallowing, gag reflex)
  • laryngeal muscles (vocals)


3 afferent sensory components

1. GSA (general somatic afferent) : touch/pain/pressure from small parts of face (pharynx/larynx, meninges of post fossa, small region of ext ear)

  • conscious sensory

2. SVA (special visceral afferent) : taste for small part of mouth (epiglottis, pharynx)

  • conscious sensory

3. GVA (general visceral afferent) : chemoreceptors and baroreceptors of aortic arch

  • subconscious sensory


CN X nuclei



multiple nuclei within the brainstem contribute to CN X → axons come together to form a single bundle at the level of the medulla


1. GVE (in dorsal motor nucleus of X) : column of cells laterally adjacent to hypoglossal nucleus on dorsal side of medulla

2. SVE (from nucleus ambiguus) : column of cell bodies dorsal to middle portion of inf olivary nucleus

3. SVA (taste) & GVA (subconsc sensory) (from nucleus solitarius) : lateral to dorsal motor nucleus of X

  • proximity to dorsal motor nucleus of X (GVE motor afferents) important for PSNS feedback!
  • forms a "U" with diff sensory inputs
    • rostral part of n. solitarius → taste signals
    • caudal part of n. solitarius → baroreceptor/chemoreceptor signals


sympathetic vs parasympathetic systems




origin of fibers


  • fight or flight
  • preganglionic: Ach
  • postganglionic: nor/epi
  • origin: intermediolateral horn (T1-L3)


  • rest and digest
  • pregang: Ach
  • postgang: Ach
  • origin:
    • CN X → PSNS up to splenic flexure
    • sacral segments S2-S4 → PSNS after splenic flexure


bilateral lesion of vagus nerve


unilateral lesion of vagus nerve

bilateral: FATAL


unilateral: widespread syxfx of palate, pharynx, larynx

  • arch sagging on affected side
  • deviation of uvula to unaffected side
  • vocal muscle paralysis on affected side



glossopharyngeal (innervates post tongue, pharynx)

both sensory/motor


2 efferent motor components:

1. GVE (general visc efferent) : pregang PSNS to ONE GLAND:

  • parotid gland

2. SVE (special visceral efferent) : from branchial arches to...

  • stylopharyngeal muscle


3 afferent sensory components

1. GSA (general somatic afferent) : touch/pain/pressure from small parts of face

  • pharynx, post 1/3 of tongue, middle ear, small region of ext ear
  • conscious sensory

2. SVA (special visceral afferent) : taste from larger part of tongue (post 1/3)

  • conscious sensory

3. GVA (general visceral afferent) : chemoreceptors and baroreceptors of carotid body

  • subconscious sensory


all in all, v similar to CN X!!!


 CN IX nuclei locations

1. GVE (pregang PSNS → parotid gland) : inferior salivary nucleus located in PONS

2. SVE (branchial arches → stylopharyngeus m.) : nucleus ambiguus 

3. SVA (taste of post 1/3 tongue) & GVA (chemo/baroceptors of carotid body) : nucleus solitarius 


lesions of CN IX and CN X

  • nucleus ambiguus
  • glossopharyngeal neuralgia

lesions of n. ambiguus

  • poliomyelitis
  • ischemic lesions
  • intramedullary tumors
  • motor neuron disease
  • neuroma
  • MG

glossopharyngeal neuralgia

  • episodes of severe throat and ear pain


testing glossopharyngeal/vagus nerve


cough test

open mouth, say AHHH

  • need CN IX, X

turn head against resistance

shoulder pushup against resistance

  • need CN XI

tongue out, movements

"yellow lorry"

swallow test


classification of CN sensory afferents

general visceral afferents (nucleus solitarius) : chemo/baror.

special visceral afferent (nucleus solitarius) : taste


medulla summary


name the nuclei and their locations relative to one another


explain the significance of the sulcus limitans in terms of embryology

motor develop from basal plate, stays mostly medial

sensory develop from alar plate, which wraps around to get to its outer/lateral positions


sulcus limitans "divides" the 3 motor nuclei and the 3 sensory nuclei


vascular supply of medulla

anterior circ : internal carotid artery

posterior circ : vertebral artery → inferior olivary nucleus

vertebral gives off PICA → lateral structures

  • anterolateral system
  • nucleus solitarius
  • vestibular nuclei
  • nucleus ambiguus
  • etc.

anterior spinal artery → midline structures

  • pyramids
  • medial lemniscus
  • hypoglossal nucleus


medial medullary syndrome


what tracts will be affected?

what sx will you see?

issue with anterior spinal artery → affects medial structures (supplied by ASA)


  • affects motor on contralateral side (rostral medulla = decussation hasnt happened yet)
  • affects disc touch/vibration/proprioception on contralateral side (medial lemniscus = decussation has happened)
  • affects hypoglossal nucleus (ipsilat bc decussation of UMN has already happened)

NO EFFECT on pain/temp in STT!



sx seen:

  • ipsilat tongue weakness
  • contralat arm/leg weakness
  • contralat decreased position/vibration sense



lateral medullary syndrome


what tracts will be affected?

what sx will you see?

issue with posterior inferior cerebellar artery → affects lateral structures (supplied by PICA)


  • affects nucleus solitarius (ipsilat)
  • affect nucleus ambiguus (ipsilat)
  • affects contralat pain/temp (hits STT)


sx seen:

  • ipsilat decreased taste
  • horaseness/dysphagia
  • contralat decreased pain/temp

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