Psarros Chapter 2 Flashcards
This connects the medial, intermediate, and lateral olfactory areas
diagonal band of Broca
Which thalamic nuclei facilitates the conscious perception of smell
projections from the pyriform cortex to the mediodorsal nucleus of the thalamus which then projects to the orbitofrontal cortex
Through what path do the olfactory areas project to the hypothalamus?
medial forebrain bundle
Through what pathway do the olfactory areas project to the habenular nuclei
stria medullaris thalami
Through what pathways does the amygdaloid body transmit to the anterior hypothalamus?
stria terminalis
what pathways facilitate visceral responses to olfactory stimuli?
through hypothalamic and habenular nuclei projections to the reticular formation
optic tracts project to the lateral geniculate bodies of the thalamus except for a small number of fibers that project to what area for the pupillary light reflex
pretectal nuclei
the upper bank of the visual cortex is comprised of this gyrus
cuneus
the lower bank of the visual cortex is comprised of this gyrus
lingual
the primary visual cortex projects to this
secondary visual cortex (areas 18 and 19)
why is there macular sparing with PCA infarcts
the occipital poles are also supplied by the MCA
what nucleus provides preganglionic parasympathetic fibers to CNIII
Edinger-Westphal
what is the route of the CNIII fibers?
the lower motor neurons pass through the red nuclei and the medial portion of the cerebral peduncles before exiting. CNIII passes between the PCA and the SCA before entering the cavernous sinus. It hugs the lateral border of the cavernous sinus and enters the superior orbital fissure, then through the annulus of zinn before dividing into superior and inferior divisions
which portion of CNIII do the parasympathetic fibers exit
they exit the inferior division of CNIII to synapse in the ciliary ganglion. Postganglionic fibers innervate the constrictor pupillae and the ciliary muscles.
What are the signs and symptoms of a lower CNIII lesion
ipsilateral ptosis, pupillary dilation, accomodation paresis, diplopia, and downward, abducted eye deviation.
where is the trochlear nucleus?
at the level of the inferior colliculus in the mesencephalon
Which cranial nerve exits the brainstem dorsally
CNIV
What path does CNIV take?
exits the brainstem dorsally and decussates through the superior medullary velum (roof), then courses lateral to the cerebral peduncles and passes between the posterior cerebral and superior cerebellar arteries lateral to CNIII. It eventually pierces the tentorium cerebelli before entering the lateral wall of the cavernous sinus. It passes above the annulus of Zinn through the superior orbital fissure
What nerve decussates outside of the CNS?
CNIV
What results from CNIV lesion?
extorsion of the ipsilateral eye with diplopia on downward gaze. As a result, patients tilt their head contralaterally to compensate (Bielschowsky’s sign)
What CN is a/w the first branchial arch?
Trigeminal
what composes the trigeminal nerve
portio major (sensory) and portio minor (motor)
where is the trigeminal ganglion?
meckels cave
pathway of the trigeminal nerve?
V1: superior orbital fissure
V2: foramen rotundum
V3: foramen ovale
V1/2 travel through the cavernous sinus. The motor portion travels along V3
Major branches of the trigeminal nerve?
V1: lacrimal, frontal, and nasociliary (passes through annulus of zinn)
V2: zygomatic, infraorbital, pterygopalatine, meningeal
V3: buccal, auriculotemporal, lingual, inferior alveolar, and meningeal
Special sensation of trigeminal nerve?
Anterior two thirds of taste and external surface of the tympanic membrane through V3
what portions of the dura are innervated by CNV?
anterior and middle fossa
What does the SVE component of CN5 innervate?
muscles of mastication (first branchial arch): tensor veli palatini, tensor tympani, masseter, pterygoids, temporalis, mylohyoid, anterior body of the digastric
nuclei of the trigeminal nerve
- motor
- sensory
- mesencephalic: proprioception from mastication muscles
- nucleus of the spinal tract: pain and temperature sensation from the face (from pons to the cervical spinal cord)
what is the only ganglion in the CNS?
trigeminal mesencephalic nucleus: primary sensory nerves for proprioception from the muscles of mastication
what is equivalent to the spinal cord substania gelatinosa in the brainstem?
spinal nucelus
what is equivalent to the spinal cord Lissauer’s tract in the brainstem?
spinal tract
where do the secondary neurons from the main sensory and spinal nuclei of the trigeminal nerve synapse?
VPM
What is in the dorsal trigeminal lemniscus?
crossed and uncrossed afferents mediating touch from the face
what is in the ventral trigeminal lemniscus?
crossed: touch and pain and temperature from face
what reflexes is the trigeminal nerve involved?
afferent corneal and efferent auditory reflex
what cranial nerve has the longest course?
abducens (CNVI)
where is the CNVI nucleus located and what is its course?
pontine tegmentum
exits ventrally between pons and pyramid of the medulla. It enters the cavernous sinus through dorello’s canal (just medial to petrous apex). It travels just lateral to the carotid artery in the cav sinus, then through Zinn
what is the result of lesions of the abducens nerve and nuclei?
Nerve: ipsilateral lateral rectus muscle weakness
nuclei: ipsilateral lateral gaze palsy involving both ipsilateral lateral rectus and contralateral medial rectus because the MLF is involved
What innervates the second branchial arch
Facial Nerve
course of the facial nerve to GSPN
Exits the pons as large motor branch and nervus intermedius.
Enters internal auditory meatus and traverses petrous bone.
Greater superficial superior petrosal (GSPN) nerve branches after geniculate ganglion toward pterygopalatine ganglion
Course of the facial nerve after GSPN
courses laterally and caudally along facial canal
- chorda tympani branches
- exits skull at stylomastoid foramen
muscles of the second branchial arch?
stapedius, stylohyoid, posterior belly of the digastric, occipitalis, frontalis, orbicularis oris and oculi, platysma, and buccinator
General visceral efferent for CNVII?
parasympathetic to lacrimal, submandibular, sublingual, and palates.
path of the GSPN?
exits the middle fossa via foramen lacerum
combines with the deep petrosal nerve in the pterygoid canal before synapsing at the pterygopalatine ganglion
where are the cell bodies of the sensory neurons of CNVII located?
geniculate ganglion
pathway for taste from ant 2/3 of tongue?
chorda tympani -> nervus intermidius ->solitary tract ->rostral solitary nucleus (gustatory)
facial nerve lesions relative to the geniculate ganglion?
hyperacusis, loss of anterior taste, decreased salivation,
Lesions proximal also cause impaired lacrimation
What are crocodile tears?
aberrant regeneration of preganglionic parasympathetic fibers that originally projected to the submandibular ganglion may enter GSPN after proximal CNVII lesions -> lacrimation in response to salivatory stimuli
what kinds of signals differentiate the dorsal and ventral cochlear nuclei?
high frequency signals are conveyed by the dorsal nuclei while low frequency goes to the ventral
through what portion of the internal capsule do fibers that travel through the medial lemniscus project?
posterior
what is analogous to the nucleus of Clarke in the brainstem for the upper extremities?
accessory cuneate nucleus, which gives rise to cuneocerebellar fibers that become mossy fibers and terminate in the anterior lobe
most excitatory fibers of the CNS?
climbing fibers (glutamatergic), which generally (inferior) olivo-cerebellar fibers that comprised the majority of the inferior cerebellar peduncle
only paired circumventricular organ?
area postrema
how does the medullary reticular formation and the thalamus connect?
efferent fibers from the gigantocellularis nucleus ascend in the central tegmental tract to synapse in the intralaminar nuclei of thalamus
restiform and juxtarestiform bodies?
form the inferior cerebellar peduncle
restiform body contains climbing fibers (olivocerebellar), dorsal spinocerebellar, cuneocerebllar, reticulocerebellar, and nucleocerebellar
juxtarestiform: vestibulocerebellar fibers (mossy fibers)
what do the perihypoglossal nuclei involved in?
oculomotor function
blood supply of the medulla?
anterior and posterior spinal arteries, PICA, and branches of the verts
what does PICA occlusion cause?
lateral medullary syndrome (Wallenberg)
ips loss of pain/temp from face, contra loss of pain/temp from body, ips larynx and pharynx function, ips horners, vertigo/ataxia/nausea
but clinically the most common cause of Wallenberg is vert dissection
what is the Barany chair used for
evaluation of post-rotational flow of endolymph fluid motion
what does the mnemonic COWS mean?
describes the effect of external ear irrigation on the fast phase of nystagmus (opposite of VOR)
loss of cortical input to these nuclei cause decerebrate posturing
vestibular nuclei
blood supply of the pons
branches of the basilar artery
occlusion of the paramedian branches of the pons?
Millard-Gubler syndrome or ventral pontine syndrome
-ips facial paralysis, ips gaze palsy, contra hemiplegia
What passes through the superior cerebellar peduncle?
efferent fibers from the dentate, emboliform, and globose nuclei and
afferent fibers from the ventral spinocerebellar, rubrocerebellar, tectocerebellar, tracts
highest concentration of substance P in the CNS
substantia nigra
inferior colliculi
receives auditory (tonotopic) fibers from the lateral lemniscus and projects to the medial geniculate body of the thalamus
superior colliculi
receives input from the retina and visual cortex superficially while deep input is from reticular formation, auditory, and motor systems
superficial sup colliculi projects to the lateral geniculate and pulvinar
deep sup colliculi projects to PPRF, RiMLF, spinal cord, cranial nerves, and retic form
what passes through the posterior commisure?
crossing fibers from the pretectal nuclei, the INC (interstitial nuclei of cajal), the nuclei of Darkshewitsch, and nuclei of the posterior commisure
what is the only circumventricular organ to have an intact blood-brain barrier?
the subcommissural organ, which is located in the ependyma of the cerebral acqueduct beneath the posterior commissure.
what composes the ascending reticular activating system (ARAS)?
projections from the reticular formation (medullary, pontine, and mesencephalic) to the intralaminar nuclei of the thalamus.
Also PPN participates and all connections are inhibitory
What does occlussion of the paramedian branches from the p-comm and PCA cause?
Weber’s syndrome: ipsilateral oculomotor palsy and contralateral hemiplegia
what is the extrageniculate visual pathway
projections of the pulvinar to the visual cortex
