motor pathways brainstem systems

lenticulostriate arteries of M1

irrigates genu of internal capsule

reticular formations, cranial nerve motor, LMNs

targets of corticobulbar tract: majority to _____ _____, and minority to ____ ____ ____ nuclei (___)

V, VII, IX, X, XII

CNs involved in corticobulbar tract

bilateral, lower quadrant, facial nucleus, hypoglossal nucleus

most CN motor nuclei receive _____ corticobulbar inputs - the two exceptions are the _____ ___ of ____ ____, and the _____ _____

eye, III, IV, VI, brainstem pattern generators, superior colliculus

CNs for ____ movements (CNs?) do not receive direct corticobulbar inputs but are activated by _____ ____ ____ controlled by ____ _____

frontal, parietal, internal capsule, corticopontine

____ and ____ eye fields can activate pattern generators in brainstem associated with eye movements - axons travel through ____ _____ in ______ system

at level of nuclei they innervate

crossed corticobulbar fibers decussate where?

pre-olivary sulcus, pyramids, olive, will, dysphagia, dysarthria

hypoglossal: axons travel obliquely through the medulla to emerge from the ___-_____ _____ between the _____ and _____. unilateral damage will/will not lead to deficits? XII lesions —> trouble swallowing (_____) and trouble articulating (______)

ASA both

XII nucleus and nerve fascicle vascular territory

lateral rectus, abduction

VI muscle and movement

superior oblique, depresses adducted eye

IV muscle and movement

fascia bulbi, sclera

6 extraocular muscles pierce the ____ ____ to insert on the ____

superior rectus (III) and inferior oblique (III)

extraocular muscles that elevate eye with CNs

inferior rectus (III), superior oblique (IV)

extraocular muscles that depress eye with CNs

medial rectus (III)

extraocular muscles that adducts eye with CNs

lateral rectus (VI)

extraocular muscles that abducts eye with CNs

basilar

VI nucleus and nerve fascicle vascular territories

abducens nucleus or nerve damage

eye on affected side drifts medially and fails to abduct past midline on horizontal conjugate gaze to that side

trochlear nucleus, dorsal, caudal

axons decussate in superior medullary velum and emerge from ____ surface of brainstem just _____ to inferior colliculi

IV, depress, intort

superior oblique CN and action when eye is medial and when eye is lateral

SCA

irrigates trochlear nucleus and proximal nerve

trochlear nerve or nucleus lesion

diplopia that is worse when looking down and medially. compensation for extorsion of eye by tilting head toward non-lesioned side and forward to allow affected eye to view near objects

dorsolaterally, ventrally

unlike the trochlear nerve (runs _______), oculomotor nerve fibers pass _____ through the tegmentum

basilar and PChA

oculomotor nucleus and nerve vascular territory

levator palpebrae superiorisis, superior, inferior, and medial recti, inferior oblique

muscles irrigated by oculomotor nerve

oculomotor nucleus or nerve lesion

down and out, dilated pupil, ptosis, loss of pupillary light reflexes

PCOM, aneurysms

oculomotor nerve runs parallel with _____, it is therefore vulnerable to _____ in that

horizontal conjugate gaze, abducens

lateral movements of both eyes, driven by ______ nucleus

MLF, oculomotor, medial rectus, horizontal, MR, LR

abducens nucleus has interneurons that sends axons through _____ to contralateral _____ nucleus (_____ _____ portion) - causes synchronous contraction for _____ conjugate gaze. __ and __.

horizontal conjugate gaze

lesions of VI nucleus or fibers in MLF lead to ____ _____ ____ palsy

internuclear ophthalmoplegia, cannot, can

lesion to one side of MLF will produce _____ _____. when looking to side opposite of lesion, the ipsilateral eye ____ turn medially, and the contralateral eye ____ turn laterally and shows nystagmus

vertical conjugate gaze, SR, IR, SO, IO

_____ _____ ____ controlled by neurons in rostral midbrain - close to oculomotor nucleus and PAG. Coordinates actions of which muscles?

rostral dorsal, downwards

lesions affecting the ____ ____ midbrain can lead to paralysis of vertical gaze (usually eyes point ______)

pattern generators, brainstem tegmentum, VI, III, IV

cortex generates saccades via ____ _____ in _____ _____, these engage ___ nucleus for voluntary horizontal conjugate gaze, and the ____ and ___ nuclei for voluntary vertical conjugate gaze

frontal eye fields, parietal eye fields, superiorcolliculus, corticopontine

supranuclear command over brainstem nuclei responsible for saccadic eye movements (2x) - project mostly to _____ ____ via _______ pathways

frontal eye fields

in premotor cortex, govern initiation of contralateral voluntary saccadic eye movements and smooth pursuit and vergence eye movements

parietal eye fields

in posterior parietal cortex, produce signal for visual-evoked saccades and play a role in smooth pursuit

superior colliculus, saccadic, gaze, reticular formations, omnipause, reticular

receives visual inputs from retina and command inputs from cerebral cortex - if strong enough, an input can induce ______ eye movements, projects to ____ centers in brainstem ______ ______, inhibiting _____ neurons, which are clusters of pontine _____ neurons that fire continuously except just prior to and during saccades

inhibit, paramedian pontine reticular formation, MLF, pons, rostral interstitial nucleus of MLF, MLF, upper midbrain

at resting state, omnipause neurons constitutively _____ populations of burst neurons - two populations of burst neurons: _____ ____ ____ ____ for horizontal saccades near ____ in ____, and ____ ______ ____ __ ____ for vertical saccades within ____ in ____ _____

neural integrator, step signal

to maintain eccentric gaze - burst neurons also send collaterals to a _____ ____ - generate a ____ ____ to extra-ocular muscles

nucleus prepositus hypoglossi, MLF, medulla, interstitial nucleus of Cajal, MLF, upper midbrain

two populations of neural integrators: _____ ____ ____ for horizontal saccades near ___ in _____, and ______ _____ _ ____ for vertical saccades within ____ in ____ _____

PPRF lesion

inability to make saccades to side of lesion (horizontal), can be overcome with VOR

abducens nucleus lesion

inability to make horizontal eye movements, can not be overcome with VOR

MLF lesion (internuclear ophthalmoplegia)

inability to adduct ipsilateral eye during horizontal eye movements, can be overcome with vergence

vergence, medial rectus, near response, MLF, edinger-westphal, near triad, synkinesis

converging eyes toward midline recruits bilateral ____ ____ muscles using ____ ____ cells in rostral midbrain, which bypass the ____. They also activate the _____-____ nucleus, resulting in all three being the ____ ____ (______)

near triad (synkinesis)

eye convergence (medial recti), accommodation of lens, constriction of pupil

accessory nucleus, foramen magnum, jugular foramen, trapezius, sternocleidomastoid, extends

within upper cervical spinal cord ventral horn, enter skull via ____ ____ and leave via ____ ____ and supplies _____ and ________. The former ____ the neck, and the latter turns the face to the opposite side and can flex the neck

accessory nucleus or nerve damage

winging of scapula, loss of shoulder profile, difficult raising arm above shoulder level —> permanently turned head to damaged side

nucleus ambiguus, IX, X, post-olivary sulcus

motor innervation to pharynx, larynx, soft palate, and upper esophagus via CNs __ and __(mainly) . at midpoint of line between _____-_____ ____ and hypoglossal nucleus

nucleus ambiguus or IX/X nerve lesion

atrophy and flaccid paralysis of soft palate, pharynx, larynx —> dysphagia and dysarthria - uvula may deviate to contra-lesional side

IX, X, spinal V, nucleus ambiguus, VTT

gag reflex is a test of ___, ___, and ____ ____ function. sensory information is sent to bilateral ____ ____ via the ____

facial nucleus, pons

innervates muscles of facial expression, stylohyoid, posterior digastric, and stapedius, in the _____

abducens nucleus, dorsal, facial colliculus

VII axons wrap around the medial edge of the ____ ____ and pass over its _____ surface before exiting - raises a hillock visible in IV floor: ______ ______

facial nucleus UMN lesion

lower quadrant palsy

facial nucleus or nerve lesion

facial hemiplegia and hyperacusis

eight and a half syndrome, abducens, ophthalmoplegia

caudal tegmental pontine syndrome - unilateral - horizontal gaze palsy (___ nucleus), internuclear _________, facial nerve palsy

corneal blink reflex

involves facial nucleus and rostral spinal trigeminal nucleus - consensual reflex

jaw jerk reflex

consensual reflex between V nuclei - mesencephalic and motor - exaggerated in corticobulbar lesions

pseudobulbar palsy

bilateral interruption of corticobulbar fibers —> UMN weakness of muscles of head

locked-in syndrome

large lesions of basal pons - damage all corticospinal and corticobulbar pathways bilaterally - total complete paralysis of voluntary muscles

hypoglossal nucleus

abducens nucleus, MLF

trochlear nucleus, MLF

CN VI palsy

superior rectus (III), inferior oblique (III), lateral rectus (VI), medial rectus (III), inferior rectus (III), superior oblique (IV)

• what cranial nerve supplies

oculomotor nuclear complex, MLF

CN IV palsy

CN III palsy

medial rectus, lateral rectus, VI, III, MLF

supranuclear command, PPRF, riMLF, eccentric, neural integrator, ppH, IC

accessory nucleus

near response cells, rostral midbrain

LMN VII lesion, UMN VII lesion

nucleus ambiguus

facial nucleus, abducens nucleus, MLF

Motor V nucleus