Brainstem and Medulla Flashcards by Nathan Hansen

Brainstem

Continuous w/ thalamus at TI

Continuous w/ SC at foramen magnum

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Tegmentum

Continuation of SC, posterior
Major ascending tracts
Nuclei of CN 3-12

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Basilar region

corticospinal tracts
Nuclei involved in motor circuits
Pyramids of medulla

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Midbrain tectum

Superior Colliculus- NC visual processing

Inferior Colliculus- NC auditory processing

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Vertebral Artery/ ASA

Enters via foramen magnum, forms Basilar artery (pons/medulla)
Paramedian branches, on the midline

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Long/Short circumferential aa

pass around lateral aspect of brainstem towards the ventricle (eg PICA)

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CN at the brainstem
Midbrain
Pons
Medulla

3,4
5-8
5,9-12
nuclei located in these same regions, (CN V as exception)

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Embryology

Motor=midline
Somatomotor- muscles, midline (tongue, eye)
Visceral motor- glands, digestive system etc, just off midline
Visceral sensory= just outside
Somatosensory nuclei
Special nuclei- vestibular (dorsolateral)

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Lesion of midline affects

Paramedian branches
Pyramidal tract- contra leg/arm UMN signs
Hypoglossal nerve/nucleus- ipsi tongue weakness

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CN 5 (GSA)

Sensory to head

Motor to mastication and others

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Trigeminal ganglion

location of pseudounipolar cell bodies
Spinal trigeminal nucleus- pain/temp/crude touch
Principal nucleus of CN V= fine touch, proprioception
Mesencephalic nucleus of CN V= proprioceptive reflex for muscles of mastication
Also motor of CN V

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1st
2nd
3rd order neurons of Spinal trigeminal tract

1st- trigeminal ganglion, descend in STT and synapse on ipsilateral ST nucleus (think SG)
2nd- fibers cross to form ventral trigeminothalamic tract and synapse on contralateral VPM of thalamus
3rd- ascend through internal capsule and synapse on ipsi PSC

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PSCT
ASCT
LSTT

ipsilateral NC proprioception to the lower limb (go to cerebellum)
crossed NC proprioception to cerebellum
crossed tract for pain/temp fibers to thalamus

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Lesion on left side

Loss pain ipsi face
Loss pain contra body
Ipsi ataxia to lower limbs

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Pyramids

At decussation

anterior surface of medulla, contain descending CS/CN tracts

cross and move posterior/lateral to innervate anterior horn neurons

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Fibers at tip/base

Tip- crossed

Base- not crossed

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Medial longitudinal fasciculus

Posterior to tectospinal

carry Medial vestibulospinal fibers for neck/upper axial muscles

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Tectospinal

Lateral vestibulospinal tract

innervate neck muscles (adj to decussation)

innervates extensor muscles

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Accessory nucleus

Above decussation, innervate trapezius/sternocleidomastoid
LMN in the anterior horn of Cspine
Damage- ipsi shoulder droop and cant turn head to contra side

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Hypoglossal nerve (GSE)

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intrinsic/extrinsic tongue muscles
leave between pyramid/olive
Lesion- ipsi tongue atrophy/fasciculations/tongue deviation
Lesion of pyramids- UMN signs

DMN of Vagus (CN X)

NTS

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Parasympathetic preganglionic neurons
Baroreceptor/chemoreceptor fibers (CN IX)
also respiratory/heart/GI visceral afferent fibers (CN X)

Nucleus ambiguus

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CN IX and X somatomotor fibers innervating head/neck skeletal muscles and neurons to innervate the heart
motor to palate

Formation of Medial Lemniscus

Lesion

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NG/NC send fibers across midline
Lower limbs- anterior
Upper limbs- posterior
Head/neck- CN V ganglion
Lesion= contralateral signs (if midline, will see hypoglossal/pyramidal signs)

Glossopharyngeal CN IX

Vagus

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visceral sensory, stretch and BP

PNS outflow to heart

Hypothalamic tract

sympathetic fibers pass to IML | Lesion- lose all sympathetic outflow

Central tegmental tract

CTT | input to IO from red nucleus of midbrain

Vagus nerve SVE and signs

``` cell bodies in NA, innervate pharynx/larynx/soft palate Motor part of gag reflex Dysphagia Dysphonia Dysarthria Drooping palate on side of lesion Uvula deviates to opposite side ```

Vagus nerve GVE

PNS neurons located in DMN of Vagus Postganglionic neurons located in ganglia innervate smooth muscle of trachea/bronchi/abdomen/heart

Vagus nerve GSA

cell bodies of origin in superior ganglion of CNX tympanic membrane terminate in STN

Vagus nerve GVA

cell bodies of origin in nodose ganglion innervate bronchi/heart/esophagus/digestive tract taste from epiglottis/palate terminate in NTS

Vagus nerve SVA

taste buds from epiglottis/palate | terminate in NTS

Lateral Medullary syndrome (Wallenberg's syndrome/PICA syndrome) Effects

Circumferential branches (PICA) Spinothalamic- contra pain/temp SCT- ipsi proprioception/ataxia STT- ipsi pain/temp in face Vagus/NA- ipsi weak gag/swallowing reflex, dysarthria Hypothalamic fibers- miosis, ptosis, flushed face, dec sweating

R/F Raphe nuclei

ascending/desceding fibers to all regions Des- pain modulation in dorsal horn Asc- limbic system cnxn and arousal circuits (basal firing rate)

Medial R/F

outflow asc/des tracts

Lateral R/F

Collateral branches from asc sensory tracts descending collaterals from higher brain regions Coordinates local circuits with medial R/F

R/F important

complex/receptive orofacial motor- tongue movement/cheeck compression/swallowing CV and respiratory homeostasis Macturition center (urination)

ANS

Maintain homeostasis- maintiain equilibrium by adjusting physiological processses

Sympathetics | Parasympathetics

T1-L2, fight/flight (acetylcholine/Norepi-epi) | S2-S4/CN= rest/digest (acetylcholine)

Sympathetics

Can terminate on 2nd neuron @ the level it entered Can ascend/descend to terminate on 2nd neuron Can pass through w/o terminating as splanchnic nerve, which terminates in collateral ganglia (BV)

Parasympathetics

1st cell bodies- CN3/7/9/10 or S2-S4 | 2nd cell bodies- walls of organs (ciliary/otic/ptergopalatine/submandibular ganglion)

Somatic (spinal) reflex

discharge of an efferent somatic motor neuron in response to afferent stimulation of sufficient intensity Go to DH, then LMN in ventral horn at same level

Visceral reflex (longer distance)

discharge of an efferent visceral motor neuron in response to afferent stimulation of sufficient intensity converge @ NS, goes to R/F or CN nuclei

Rostral ventrolateral medullary pressor area (RVLM)

active neurons send monosynaptic projections to IML w/ symp pregang neurons Inc tone to BV/heart

termination of baroreceptor/chemoreceptor neurons

Caudal ventrolateral medullary depressor area (CVLM)

Gaba-ergic neurons that projects to RVLM | Allows parasympathetic tone to heart/BV

HBP | LBP

CVLM active, inhibits RVLM | Less CVLM, more RVLM

R/F helps to coordinate

respiration | in reticular areas of medulla

Hypothalamus

controls what ANS is trying to achieve | Parabrachial nucleus- relay NTS to higher functional areas

Hypothalamus pt 2

control over temp, symp/para events, endocrine function of pituitary, sexual behavior, feeding/drinking/aggression/flight

Brainstem and Medulla Flashcards

(49 cards)