Anatomy - Spinal Trigeminal Nucleus Flashcards Preview

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Flashcards in Anatomy - Spinal Trigeminal Nucleus Deck (17)
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describe the path of the spinal trigeminal nucleus

afferents enter pons and turn caudally to descend in the spinal trigeminal tract which then becomes continuous with Lissauer's tract in upper cervical cord


what are the three divisions of the spinal trigeminal nucleus and which does the most with pain and temperature sensation to the face

pars caudalis (most inferior, most involved with pain and temperature to face for CN V)
pars oralis
pars interpolaris


what is the significance of the spinal trigeminal tract merging with Lassauer's

it allows for a uniform pain/temp sensation for the face instead of dividing it into distinct sections


where is the pars oralis division of the spinal trigeminal nucleus

most rostral part
- extends from main sensory nucleus to pontomedullary junction


where is the pars interpolaris located

in the rostral medulla in between pars oralis and pars caudalis
- extends from superior medulla to obex


where is the pars caudalis located

from C2, C3 to the obex


compare more caudal lesions of the pars caudalis to more rostral lesions

caudal: the more caudal the lesion, the larger the area of sensory loss with the mouth spared

rostral: sensory loss starts at the back of the head and moves forward towards mouth

(onion peel sensory loss)


describe the pathway of primary afferents coming in from trigeminal using the spinal nucleus (pain and nociception from face)

primary afferents come in and synapse onto trigeminal ganglion --> enter midbrain and descend along spinal trigeminal tract until reaching pars cadualis --> contacts 2nd order neurons in pars caudalis --> cross contralaterally --> ascend as the anterior trigeminothalamic tract to VPM


describe the trigemino-reticulo-thalamic pathway

pain fibers project bilaterally to the reticular formation as trigeminoreticular fibers --> facilitates ascending reticular activating system (ARAS) --> plays and important role in arousal and alertness


what kind of info does the pars oralis receive

tactile information from central region of face


what kind of info does the pars interpolaris receive

info from peripheral region of face


information from the pars oralis and interpolaris go where along with the contralateral thalamus

project fibers to the cerebellum along with the contralateral thalamus


sx of a unilateral lesion of the trigeminal

- anesthesia in trigeminal dermatomes
- loss of jaw-jerk reflex
- atrophy of muscles of mastication
- loss of ipsilateral and consensual corneal reflex


what is alternating analgesia

where lesions in the upper medulla or lower pons destroys fibers in spinal trigeminal tract and in the medial leminiscus
--> ipsilateral hemianalgesia of face and contralateral hemianalgesia of body


what is alternating hemiplegia

lesion causing unilateral destruction of trigeminal nerve and corticospinal tract in the pons
--> causing ipsilateral trigeminal anesthesia and paralysis and contralateral spastic hemiplegia


sx of Wallenberg's and why

contralateral loss of pain and temp of body with ipsilateral loss of pain and temp over face

- damage to the PICA affects ALS and the spinal trigeminal nucleus (ALS controls contralateral pain and temp to the body and trigeminal controls ipsilateral pain and temp to face)


describe the corneal reflex

afferent limb: trigeminal
efferent limb: facial

irritating stimulus to cornea --> activates C fibers whose cell bodies are in trigeminal ganglion --> axons descend spinal trigeminal tract --> terminal in spinal trigeminal nucleus in pars caudalis --> en route to VPM fibers are sent to facial motor nucleus --> innervate orbicularis oculi to close eyelids