Pons Flashcards

Terms Definitions
pons anatomy
dorsal tegmentum (contains reticular formation and CN nuclei) and ventral basilar portion (transverse fibers and corticospinal tract)
ascending pathways
DCML, spinothalamic and trigeminothalamic tracts, MLF, middle cerebellar peduncle, superior cerebellar peduncle, trapezoid body and lateral lemniscus, basilar pons
trigeminothalamic tract
conveys sensory info from head; spinal nucleus (in medulla) receives pain and temp sensation, main sensory nucleus (in pons) receives tactile info
only ascending fibers at and above level of pons- damage to this area disrupts eye movements and produces nystagmus
middle and superior cerebellar peduncles
middle: in pons, formed by TPFsuperior: in upper pons and medullaanterior spinocerebellar tract carries info about unconscious proprioception from GTO to cerebellum via entrance through sup. cerebellar peduncle; cerebellum feeds back to cortex via fibers from sup. cerebellar peduncle
trapezoid body
site of decussation of auditory relay pathway
lateral lemniscus
formed by fibers of auditory relay pathway after they cross midline at trapezoid body
basilar pons
composed of transverse pontine fibers, which converge laterally to form the middle cerebellar peduncle
descending pathways
rubrospinal tract, MLF (only ascending fibers here, but contains desc fibers in medulla), reticulospinal and vestibulospinal pathways, and basilar pons
descending tracts of basilar pons
corticospinal, corticobulbar, and corticopontine fibers
abducens nucleus
motor input to lateral rectus; GSE, close to floor of 4th ventricle
facial nucleus
SVE axons, innervate muscles of ipsilateral facial expression
superior salivatory nucleus
GVE, preganglionic parasympathetic axons of CN VII, which innervate submandibular, sublingual, and pterygopalatine ganglia; mediate lacrimation and salivation
superior olivary nucleus
part of auditory relay complex, w/ trap. body receives auditory inputs from cochlear nuclei
raphe nucleus
midline region of reticular formation; only site of serotonin production; cells ascend/descend into midbrain/medulla
sensory and motor nuclei of CN V
GSA, project to VPM nucleus of thalamus; GSE (?) motor axons project to muscles of mastication
locus ceruleus
largest norepi-producing region in the brain, involved in wakefulness and motivative behaviors
mesencephalic nucleus
receives muscle spindle afferents from the jaw and related areas - afferents for reflex closing of jaw (unconscious proprioception)
deep pontine nuclei
in basilar pons, give rise to transverse pontine fibers, which travel contralaterally to form middle cerebellar peduncle- nuclei that receive inputs from cerebral cortex and send their axons (TPF) to cerebellar cortex
caudal pons contents (nuclei; fiber pathways)
CN VIII, VII, VI, V, superior olivary nucleus, reticular formation; corticospinal, corticobulbar, corticopontine, middle and inferior cerebellar peduncles, trapezoid body, medial lemniscus, tract of CN V, spino and trigeminothalamic tracts, MLF
facial colliculus
bulge into fourth ventricle resulting from axon of CN VII first moving dorsally to wrap around the CN VI nucles before traveling ventrolaterally to exit at lateral aspect of basilar pons
rostral pons contents (nuclei; fiber pathways)
CN V, reticular formation, locus ceruleus, raphe nuclei; corticospinal, corticobulbar, corticopontine, medial and lateral leminusci, middle and superior cerebellar peduncles, and spino-trigeminothalamic tracts, MLF
Caudal Tegmental Pontine Syndrome
from occlusion of circumferential brs of basilar artery, impacts structures in caudal tegmentumsx: IPSI facial nerve palsy, lateral gaze palsy, and Horner's syndrome
Caudal Basal Pontine Syndrome
associated with paramedians brs of basilar artery, affects descending corticospinal tract and root fibers of CN VIsx: CONTR hemiplegia and signs of paralysis of CN VI (loss of lateral gaze in IPSI eye)
Rostral Basal Pontine Syndrome
occlusions of portions of paramedian brs of basilar artery, affects rostral 1/2 of basilar ponssx: CONTRA hemiplegia, IPSI loss of facial sensation and ability to chew
Rostral Pontine Tegmentum Syndrome
occlusion of long circumferential brs of basilar arterysx: IPSI loss of face sensation and ability to chew; CONTRA loss of pain, temp, Horner's syndrome, conscious proprioception from body and possible ataxia
Locked-In Syndrome
large infarct of basilar pons sx: paralysis of most motor fn of CONTRA body, and IPSI facial sensation and IPSI coordination, except ability to blink and display vertical gaze
Medial Tegmental Syndrome
lesion restricted to medial aspect of ponssx: IPSI facial paralysis, loss of lateral gaze on IPSI side, CONTRA loss of conscious proprioception if lesion extends ventral enough to involve medial lemniscus
One and a Half Syndrome
lesion of dorsomedial tegmentumsx: lateral gaze paralysis w/ inability to gaze to the side of lesion -pt can't move IPSI eye horizontally and CONTRA eye can only be abducted, resulting in nystagmus of that eye
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