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359 Cards in this Set
- Front
- Back
Functional components of the brainstem? (4)
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1) Cranial nerve nuclei 2) Long tracts 3) Cerebellar circuitry 4) Reticular formation and related structures.
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Anatomical components of the brainstem?
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Midbrain, pons, medulla oblongata.
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Structure dividing motor nuclei ventromedialy from sensory nuclei dorsolaterally?
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Sulcus Limitans
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Where is the sulcus limitans located?
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In the brainstem on the lateral wall of the 4th ventricle
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tectum
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"roof"; obvious only inthe midbrain and consists of the superior and inferior colliculi, which lie dorsal to the cerebral aqueduct
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Tegmentum
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"covering"; lies ventral to the cerebral aqueduct in the midbrain and ventral to the 4th ventricle in the pons and medulla
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Basis
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the most ventral portion of the brainstem, where the large collestions of fibers making up the corticospinal and corticobulbar tracts lie
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How do you distinguish sections with the superior colliculi from the sections of the inferior colliculi in the midbrain?
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Sections through the superior colliculi also inclue the oculomotor nuclei and the red nuclei while sections through the inferior colliculi include the trochlear nuclei and brachium nuclei
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What are the cerebral peduncles composed of?
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Substantia nigra + Basis pedunculi
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Major landmarks in the midbrain
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superior colliculus+oculomotor nuclei + red nuclei, inferior colliculus + trochlear nuclei + branchium conjunctivum, cerebral aqueduct, periaqueductal gray, midbrain reticular formation, medial lemnisus, anterolateral system, ad cerebral peduncles (substantia nigra + basis peduncles)
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The ventral pons consists of ___ which includes the corticospinal and corticobulbar tracts, as well as the pontine nuclei involved in cerebellar and corticospinal function.
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Basis Pontis
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What separates the pontine tegmentum from the cerebellum?
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The Fourth Ventricle.
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Pyramidal descussation
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transition between the medulla and spinal cord
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Where is the accessory spinal cord nucleus?
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Upper cervical spinal cord.
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The tegmentum of the midbrain lies ___ to the cerebral aqueduct.
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Ventral
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The tegmentum of the midbrain lies ___ to the 4th ventricle in the pons and medulla
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Ventral
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The corticospinal and corticobulbar tracts lie in the ____ of the midbrain.
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Basis
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Where do the superior and inferior colliculi lie in the midbrain?
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In the tectum
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The superior colliculi are more ___ than the inferior colliculi.
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rostral
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The oculomotor nuclei and red nuclei are contained in the _____
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Superior colliculi
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The trochlear nuclei and brainstem conjunctivum are contained in the ___
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Inferior colliculi
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The brainstem conjunctivum are aka ___
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Decussation of the superior cerebellar peduncles
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The cerebral peduncles are located in the midbrain. What do they consist of?
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Substantia nigra + basis pedunculi
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The medial geniculate nucleus is located ____ to the lateral geniculate nucleus in the rostral midbrain
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medial and dorsal
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The basis pedunculi is located ___ to the substantia nigra in the rostral midbrain
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ventral and lateral
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The red nucleus (parvocellular division) is located ___ to the cerebral aqueduct and ___ to the substantia nigra in the rostral midbrain
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ventral + lateral
dorsal + medial |
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In the caudal midbrain, the mesencephalic trigeminal tract is located ___ to the periaqueductal gray matter and ___ to the fascicles of the trochlear nerve (CN 4)
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lateral, dorsal lateral
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A lesion in the caudal midbrain immediately dorsolateral to the periaqueductal gray matter will most likely affect...
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The inferior colliculi
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In the caudal midbrain, the trochlear nucleus is surrounded by the ___. This little complex" is located immediately ventral to the ___."
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Medial longitudinal fasciculus (MLF)
periaqueductal gray matter |
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The ___ is located between the L and R superior cerebellar peduncle and decussation in the rostral midbrain.
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Median Raphe Nucleus
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Immediately caudal to the midbrain is the ___.
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Rostral pons
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The ventral pons consists of the ___ and ____.
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Basis pontis, pontine nuclei.
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The basis pontis contains the ____ and ____ tracts.
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corticospinal and corticobulbar
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The pontine nuclei are involved in ____ function
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cerebellar
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The ___ separates the pontine tegmentum from the cerebellum
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4th ventricle
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In the pontomesencephalic junction, the ____ and ___ are located immediately ventrolateral to the cerebral aqueduct.
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mesencephalic trigeminal nucleus/tract and the dorsal longitudinal fasciculus
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In the pontomesencephalic junction, the MLF is ____ to the reticular formation and ____ to the dorsal longitudinal fasciculus.
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dorsal
ventral |
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A lesion on the dorsolateral surface of the pontomesencephalic junction will most likely impinge upon which of the following?
- dorsal longitudinal fasciculus - trigeminal lemniscus - lateral lemniscus and nucleus - corticospinal fibers |
lateral lemniscus and nucleus
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A lesion that is midline immediately posterior to median raphe nucleus will most likely impinge upon which of the following?
- middle cerebellar peduncle - pontine nuclei - superior medullary velum - reticular formation |
reticular formation
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The 4th ventricle begins in the ___.
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Pons (rostral-mid, specifically)
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In the rostral/mid pons, the MLF is located midline and ___ to the 4th ventricle.
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Ventral
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In the rostral/mid pons, a lesion of the pontine nuclei will be seen on a scan ___ to the middle cerebellar peduncle and ___ to the superior cerebellar peduncle.
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medial, ventral/anterior
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In the rostral/mid pons, the principal sensory trigeminal nucleus is seen medial to the ___ and ventrolateral to the ___
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middle cerebellar peduncle, superior cerebellar peduncle
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In the rostral/mid pons, the superior vestibular nucleus of CN 8 is ___ to the 4th ventricle and ___ to the principal sensory trigeminal nucleus
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lateral, dorsomedial
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In the rostral/mid pons, the trigeminal nerve fascicles are ___ to the middle cerebellar peduncles
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medial
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In the rostral/mid pons, the medial lemniscus is located ___ to the lateral lemniscus
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medial. Duh.
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In the caudal pons, the nodulus of cerebellum extends into the ____ on the posterior side.
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4th ventricle
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In the caudal pons, the knee or the genu of CN 7 can be found here...
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adjacent to midline on the floor of the 4th ventricle
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In the caudal pons, the ___ can be found immediately dorsolateral to the genu of CN 7
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Dorsal longitudinal fasciculus
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In the caudal pons, the ___ is found immediately anterior to the dorsal longitudinal fasciculus and lateral to the genu of CN 7
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Nucleus of CN 4 (abducens nucleus)
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The deep cerebellar nuclei include (from medial to lateral):
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Fastigial, Globose, Emboliform, Dentate
(fat girls eat donuts) |
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In the caudal pons, the corticospinal and corticobulbar tracts are the most ___ structures compared with the others.
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ventral/anterior
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In the caudal pons, the CN 7 nucleus is found ___ to the genu of CN 7, ___ to the dorsal longitudinal fasciculus, and ___ to the abducens nucleus.
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ventrolateral, ventrolateral, ventrolateral
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In the caudal pons, the ___ cerebellar peduncle is located medial to the dentate nucleus, whereas the ___ and ___ cerebellar peduncles are localted lateral.
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superior
middle inferior |
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In the caudal pons, you can see the cerebellar peduncles from medial to lateral:
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superior, inferior, middle
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Where can the inferior olivary nucleus be seen?
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rostral medulla
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Where to the posterior columns and nuclei start appearing?
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caudal medulla
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Somatic Motor Nuclei (GSE)
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oculomotor, trochlear, abducens, hypoglossal; adjacent to midline
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Location oculomotor nuclei
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rostral midbrain
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Location trochlear nuclei
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caudal midbrain
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Medial Longitudinal Fasiculus
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interconnects occulomotor, trochlear, abducens, and vestibular nerve
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location hypoglossal nuclei
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form the hypoglossal trigones on the floor of the fourth ventricle
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Location trigeminal motor nucleus
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upper to mid pons, just ventral to the chief trigeminal sensory nucleus
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Parasympathetic nuclei and nerves
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Edinger-Westphal nucleus (III), Superior (VII) and Inferior (IX) Salivatory nuclei, and Dorsal motor nucleus of X
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Branchial motor nuclei
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trigeminal motor nucleus (CN V), spinal accessory nucleus (CN IX), facial nucleus (CN VII), nucleus ambiguous (CN IX, X)
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What is the trapezoid body?
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Where many cochlear nuclei decussate in the caudal pons.
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Where do all visceral afferents (special or general) travel to?
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Nucleus solitarius
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Where do Special Visceral Afferents (SVA) for taste go to?
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(VII, IX, and X) reach the rostral nucleus solitarius.
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Where do general visceral afferents (GVA) go to?
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They reach the caudal nucleus solitarius. (IX and X).
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The taste pathway continues rostrally via the ____ tract to synapse on the ___ nucleus of the thalamus.
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Central Tegmental tract. Ventral Posterior Nucleus. (VPM)
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In the rostral medulla, the nucleus solitarius gives rise to CN __, __, and __.
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CN VII, IX, X
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In the rostral medulla, the nucleus solitarius surrounds the ___.
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solitary tract of CN 7, 9, 10
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In the rostral medulla, the spinal trigeminal tract is located immediately medial to the ___ and carries fibers for CN ____
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inferior cerebellar peduncle
CN 5, 7, 9, 10 |
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In the rostral medulla, the spinal trigeminal tract is located immediately lateral to the ___
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Spinal trigeminal nucleus
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In the rostral medulla, the nucleus ambiguus is located ___ to the spinal trigeminal nucleus
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medial
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The nucleus ambiguus gives rise to tracts that form CN ___.
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9, 10 & 11
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In the rostral medulla, what is located adjacent to midline and posterior to the pyramid (corticospinal tract) and anterior to the solitary tract of CN 7, 9, and 10?
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Medial lemiscus
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In the rostral medulla, what nuclei are located posterior/dorsal to the nucleus solitarius?
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Medial and Inferior vestibular nuclei (CN 8)
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In the rostral medulla, the ___ nuclei are located immediately medial to the nucleus solitatius.
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dorsal motor nucleus of CN 10
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In the rostral medulla, what nucleus is located immediately medial to the dorsal motor nucleus of CN 10?
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Hypoglossal nucleus CN 12
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In the rostral medulla, the reticular formation is located medial to the ___ and lateral to the ___
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nucleus ambiguus
medial lemniscus |
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What are the 3 parts to the inferior olivary nucleus?
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Dorsal accessory
Principal (teethlike looking part) Medial accessory |
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In the caudal medulla, the nucleus that is adjacent to midline in the posterior/dorsal portion is called the __ nucleus and the nucleus immediately lateral to it is called the ___ nucleus.
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Gracile nucleus, cuneate nucleus
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In the caudal medulla, the ___ nucleus/tract is immediately ventrolateral to the cuneate nucleus/tract.
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Spinal trigeminal nucleus/tract for CN 5, 7, 9, 10.
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In the caudal medulla, the nucleus solitarius, dorsal motor nucleus of vagus, and the hypoglossal nucleus are all surrounding the ___
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central canal
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T/F: In the caudal medulla, the reticular formation is located adjacent to midline and immediately medial to the nucleus ambiguus.
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F: In the caudal medulla, the reticular formation is located lateral to the medial lemniscus (which are adjacent to midline) and immediately medial to the nucleus ambiguus.
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In the caudal medulla, the ___ is/are the most anterior/ventral structure(s)
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Pyramid (corticospinal tract)
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In the caudal medulla, name 3 structures that are located immediately anterior/ventral to the central canal.
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medial vestibulospinal tract
tectospinal tract medial lemniscus/sensory decussation |
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In the caudal medulla, a lesion on the dorsolateral surface will most likely impede on which of the following structures?
- gracile fascicle - cuneate fascicle - rubrospinal tract - arcuate nucleus |
cuneate fascicle
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Describe the location of the gracile nuclei and fascicle in the cervicomedullary junction.
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Adjacent to midline in the posterior aspect
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Describe the location of the cuneate nuclei and fascicle in the cervicomedullary junction.
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Immediately lateral to the gracile nuclei (which are adjacent to midline)
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Describe the location of the spinal trigeminal tract and nuclei in the cervicomedullary junction.
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Immediately lateral to the cuneate nuclei and posterior to the dorsal spinocerebellar tract and rubrospinal tract
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The spinal trigeminal nucleus has 3 portions seen in the cervicomedullar junction. Name them.
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Marginal zone
Substantia gelatinosa Magnocellular nucleus |
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The corticospinal tract crosses via the _____ in the _____ portion of the cervicomedullary junction.
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pyramidal decussation
anterior |
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In the cervicomedullary junction, the dorsal and ventral spinocerebellar tracts are located ___
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laterally
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In the cervicomedullary junction, the ___ is located immediately medial to the spinocerebellar tracts
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anterolateral system
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In the cervicomedullary junction, the ____ is located immediately medial to the anterolateral system.
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Spinal Accessory nucleus (CN 11)
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The pyramidal decussation is located immediately anterior to the ___
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central gray matter
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A lesion in the anterior portion of the cervicomedullary junction will most likely impinge on which of the following?
- lateral vestibulospinal and reticulospinal tracts - central gray matter - rubrospinal tract - cuneate fascicle |
lateral vestibulospinal and reticulospinal tracts
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In the cervical spinal cord, a midline lesion on the posterior aspect will most likely impinge upon...
- lissauer's tract - anterior corticospinal tract - rubrospinal tract - gracile fasciculus |
gracile fasciculus
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In the cervical spinal cord, a lesion on the anterolateral aspect will most likely impinge upon...
- gracile fasciculus - cuneate fasciculus - rubrospinal tract - substantia gelatinosa |
rubrospinal tract
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In the cervical spinal cord, a large lesion of the central canal area will most likely SPARE which of these?
- dorsal spinocerebellar tract - lateral corticospinal tract - spinal accessory nucleus - tectospinal tract |
dorsal spinocerebellar tract
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In the cervical spinal cord, the anterior corticospinal tract is located...
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adjacent to midline, anteriorly
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In the cervical spinal cord, what is located immediately lateral to the anterior corticospinal tract?
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Medial vestibulospinal tract
Tectospinal tract |
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In the cervical spinal cord, where are the anterior corticospinal tract, medial vestibulospinal tract, and tectospinal tract located in relationship to the ventral horns?
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Medial
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In the cervical spinal cord, if someone wanked upon an area of the posterior aspect immediately medial to the dorsal root of the spinal nerve, what structure did he most likely wank upon?
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Cuneate fasciculus
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Name the somatic motor nuclei (GSE).
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oculomotor
trochlear abducens |
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Where is the oculomotor nucleus located?
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rostral midbrain, ventral to the periaqueductal gray area
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Where is the trochlear nucleus located?
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caudal midbrain, ventral to the periaqueductal gray area
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What forms the ventral border of the oculomotor and trochlear nuclei, interconnecting them with the abducens and vestibular nuclei?
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MLF
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The hypoglossal trigones are located...
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on the floor of the 4th ventricle in the medulla
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In the 4th ventricle, name the 3 nuclei from medial to lateral
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hypoglossal
dorsal motor 10 solitary |
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The branchial motor nuclei include the trigeminal motor nucleus, facial nucleus, nucleus ambiguus, and spinal accessory nucleus. These generally lie ___ to the somatic motor nuclei and eventually end up in the ___
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lateral
tegmentum |
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The spinal accessory nucleus is located...
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in the upper 5 cervical segments
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The trigeminal nuclear complex consists of _____ and runs from the ___ to the _____.
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mesecephalic, chief sensory, and spinal trigeminal nuclei
midbrain upper cervical spinal cord |
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The mesencephalic trigeminal nucleus and tract run along the ___ edge of the periaqueductal gray matter and subserve ____.
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lateral
proprioception |
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The chief trigeminal sensory nucleus is located _____ and is _____ to the trigeminal motor nucleus.
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in the upper/mid pons
dorsolateral |
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The spinal trigeminal nucleus and spinal trigeminal tract run the length of the ___ and ___
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lateral pons
medulla |
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The spinal trigeminal nucleus is the ___ extension of the ____ of the spinal cord.
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rostral
dorsal horn |
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The spinal trigeminal nucleus conveys ____ from the ____
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pain and temperature sensation
face |
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The chief trigeminal nuclei convey ___ from the ___.
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fine discriminative touch
face |
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The dorsal and ventral cochlear nuclei wrap around the lateral aspect of the ___ at the pontomedullary junction
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inferior cerebellar peduncle
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T/F: the hearing pathways decussate at multiple levels, not at a single level.
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TRUE
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The vestibular nuclei (superior, inferior, medial, lateral) are located on either side of the brainstem on the ___ in the ___
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lateral floor of 4th ventricle
pons and rostral medulla |
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The ___ vestibular nucleus is the largest.
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Medial
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Where do fibers of the lateral vestibular nucleus go?
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They traverse the inferior vestibular nucleus and descend to the spinal cord
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All visceral afferents (special AND general) travel to the...
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nucleus solitarius
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The nucleus solitarius is located ___ to the dorsal motor nucleus of CN 10
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lateral
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The rostral nucleus solitarius is for ___ (what kind of afferent?) and CN ___ go to it.
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gustatory (taste)
7, 9, 10 |
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The caudal nucleus solitarius is for ___ (what kind of afferent?) and CN ___ go to it.
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cardiorespiratory and GI
9, 10 |
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The taste pathway goes rostrally via the _____ tract to the ____ of the thalamus, and then to the cortical taste area.
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central tegmental
VPM |
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The corticospinal and corticobulbar tracts travel in the _____ of the cerebral peduncles in the midbrian?
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middle 1/3.
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The other portions of the cerebral peduncles carry predominantly what?
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Corticopontine fibers involved in cerebellar circuitry.
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Where to medial lemniscus fibers synapse in the thalamus?
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VPL (Ventro Posterior Lateral nucleus).
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Where does the sympathetic pathway run in the brainstem?
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Laterally. In close proximity to the Anterolateral system.
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What does damage here cause?
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Horner's syndrome.
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What is locked-in syndrome?
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Absent motor function, but maintain intact sensation and cognition (verticle eye movements and eye opening spared)
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What is locked-in syndrome usually caused by?
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Infarct of the ventral pons affected the bilateral corticospinal and corticobulbar tracts
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Why are vertical eye movements, but not horizontal movements, spared in locked-in syndrome?
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Vertical eyelid movements and eyelid elevation are controlled by a region in the tegmentum of the rostral midbrain; horizontal movements depend on pontine circuits
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Usually, locked in patients eventually succumb to...
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respiratory infection or complication of paralysis
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Ataxia
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uncoordinated wavering movement
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Does ataxia typically occur ipsilateral or contralateral to the side of the lesion? Why?
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Ipsilateral; cerebellar circuits tend to decussate twice before reaching lower motor neurons
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Superior cerebellar peduncle
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contained mainly cerebellar outputs; the decussation of the superior cerebellar peduncles occur at the midbrain at the level of the inferior colliculi
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Middle cerebellar peduncle
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largest of the cerebellar peduncles; receives massive inputs from pontine nuclei (which receive inputs from the corticopontine fibers of the cerebral peduncles)
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Inferior cerebellar peduncle
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Receives inputs from the spinal cord
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The red nucleus receives inputs from _________
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superior cerebellar peduncle
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Palatal myoclonus
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movement disturbance characterized by continuous, clicking, movements of the palate; caused by interruption of the circuit from the cerebellum to the brainstem and back to the cerebellum
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The central core of nuclei that runs the entire length of brainstem is...
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the reticular formation
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The reticular formation is continuous rostrally with certain ____ nuclei and caudally with the ___
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diencephalic
intermediate zone of the spinal cord |
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What does the rostral reticular formation do?
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Maintain a conscious alert state in the forebrain
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What does the caudal reticular formation do?
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Helps carry out a variety of important motor, reflex, and autonomic functions.
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Which part of the brainstem is the reticular formation located?
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Throughout the whole brainstem; in the tegmentum
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The consciousness system is formed mainly by the ___
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medial and lateral frontoparietal association cortex (and also arousal circuits of rostral reticular formation)
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Where in the brain can a lesion cause a coma?
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rostral reticular formation and/or bilateral cerebral cortex or bilateral thalamus (especially the medial and intralaminar regions)
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Processes involved in the level of consciousness
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Alterness, Attention, Awareness
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Ascending reticular activating system (ARAS)
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areas in the rostral midbrain reticular formation and medial diencephalon; lesions in this area cause coma whereas stimulation can lead to arousal during deep anesthesia
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Where in the brain can a lesion cause coma?
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Coma is caused either by dysfunction of the upper brainstem reticular formation or by dysfunction of extensive bilateral regions of the cerebral cortex; bilateral lesions in the thalamus
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Location of cell bodies in reticular formation
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midbrain and rostal pons
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Main targets of reticular formation
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thalamic intralaminar nuclei, hypothalamus, basal forebrain
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Neurotransmitter receptors: Reticular Formation
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Unknown (glutamate?)
|
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Functions Reticular formation
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alertness
|
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Locations of cell bodies intralaminar nuclei
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thalamic intralaminar nuclei
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Main targets of intralaminar nuclei
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cortex, straitum
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Neuroreceptor receptors of intralaminar nuclei
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Glutamate?
|
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Functions of intralaminar nuclei
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Alertness
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Locations of cell bodies: midline thalamic nuclei
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micline thalamic nuclei
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Main Targets: midline thalamic nuclei
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cortex
|
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Neurotransmitter receptors: midline thalamic nuclei
|
glutamate?
|
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Function: midline thalamic nuclei
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alertness
|
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Locations cell bodies: Norepinephrine
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Pons: locus ceruleus and lateral tegmental area of pons and medulla
|
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Main targets: norepinephrine
|
entire CNS
|
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Neurotransmitter Receptors: Norepinephrine
|
alpha1A-D, alpha2A-D, Beta1-3
|
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CNS functions of Norepinephrine
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attention, sleep-wake states, and mood
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ADD is often treated with medications that enhance ___ transmission.
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Noradrenergic.
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The Locus ceruleus and Lateral Tegmental have what kind of neurons?
|
Noradrenergic.
|
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Narcolepsy
|
A sleep disorder characterized by excessive daytime sleepiness; often responds to treatment with noradrenergic-enhancing medications
|
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Location cell bodies: Dopamine
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Ventral Midbrain: substanstia nigra pars compacts and ventral tegmental area
|
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Main targets: Dopamine
|
Striatum, limbic cortex, amygdala, nucleus accumbens, prefrontal cortex
|
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Neurotransmitter receptors: Dopamine
|
D1-5
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Functions: Dopamine
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Movements, initiative, working memory
|
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Three projection systems arising from substantia nigra and ventral tegmental area
|
(1) mesostriatal (nigrostriatal) pathway (2) mesolimbic pathway (3) mesocortical pathway
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Mesostriatal pathway
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arises mainly from the substantia nigra pars compacta and projects to the caudate and putamen
|
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Dysfunctions of the mesostriatal pathway produces movement disorders such as?
|
Parkinson's Disease.
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The mesolimbic pathway arises mainly from where? And projects to where?
|
Ventral tegmental area and projected to the limbic structures. (Medial temporal cortex, amygdala, cingulate gyrus, and nucleus accumbens.)
|
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The mesolimbic pathway plays a major role in what?
|
Reward circuitry and addiction.
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Overactivity of the mesolimbic pathway is thought to be important in the "positive" symptoms of what? Examples?
|
Schizophrenia. Sucha s hallucinations, which often respond to dopaminergic antagonists.
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Mesocortical pathway arises mainly from where? And projects to where?
|
From the ventral tegmental area and projects to the prefrontal cortex.
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The mesocortical pathway has what roles?
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proposed in frontal lobe functions such as working memory and attentional aspects of motor initiation.
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Damage to the mesocortical pathway may be important for some of the cognitive defects and hypokinesia seen in what disease?
|
Parkinson's Disease.
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Damage to the mesocortical pathway may be important for some of the "negative" symptoms of what disease?
|
Schizophrenia.
|
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Locations of cell bodies for serotonin
|
midbrain, pons, and medulla: raphe nuclei; small amounts have been found in the area postrema and caudal nucleus ceruleus
|
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Main targets: Serotonin
|
Entire CNS
|
|
Neurotransmitter receptors: Serotonin
|
5-HT1A-F, 5-HT2A-C, 5-HT3-7
|
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Functions: Serotonin
|
Alertness, mood elevation, breathing control, temperature and pain modulation
|
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Diseases associated with serotonin
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depression, anxiety, OCD, aggressive behavior, an certain eating disorders; SIDS
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Sudden Infant Death Syndrome (SIDS) is associated with what?
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Defects in serotonin neurons, possibly causing impaired arousal in response to hypoventilation.
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Locations of cell bodies: Histamine
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Hypothalamus: tuberomammillary nucleus; midbrain; reticular formation
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Main targets: Histamine
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entire brain
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Neurotransmitter receptor: Histamine
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H1-3
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Functions Histamine
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Alterness
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Side effects of antihistamine medications
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drowsiness
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Locations of cell bodies: Orexin (hypocretin)
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Posterior lateral thalamus
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Main targets: Orexin
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Entire brain; cerebral cortex
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Neurotransmitter Receptor: Orexin
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OX1, OX2
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Functions: Orexin
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Alterness and food intake; orexins excite the brainstem and hypothalamic arousal systems and are crucial for the alert state
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Locations cell bodies: ACh
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(1) Basal forebrain: nucleus basilis, medial septal nucleus, and nucleus of diagonal band (2) Pontomesencephalic region: pedunculopontine nucleus and laterodorsal tegmental nucleus
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Main targets: ACh
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(1) Cerebral cortex including hippocampus (2) Thalamus, cerebrm, pons, medulla
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Neutrotransmitter Receptors: ACh
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Muscarinic, nicotinic subtypes
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CNS Functions of ACh
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Alertness, memory, learning
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Cholinergic projections to the hippocampal formation arise from _____ and _______
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medial septal nuclei and the nucleus of the diagonal band
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Hippocampal theta rhythm
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postulated to play a role in memory functions; rhythmic oscillation due to ACh
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Main cholinergic receptor in the CNS?
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Muscarinic.
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Pharmacological blockage of central cholinergic tranmission causes
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delirium and memory deficits
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Degeneration of cholinergic neurons in the basal forebrain may be responsible for the memory decline in which disease?
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Alzheimer's disease.
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Cholinergic inputs to the cortex mainly come from ___
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Basal forebrain (nucleus basalis of Meynert)
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Diffuse (Widespread) projection systems
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pathways which emanate from a single region to innervate many structures or even the entire nervous system
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Main excitatory neurotransmitter in the CNS
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glutamate
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Main inhibitory neutrotransmitter in the CNS
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GABA
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Lesions or blockades of some neurotransmitter systems, especially ACh and histamine will cause
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confusion and drowsiness; NOT COMA
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Location of Adenosine receptors
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thalamus and cortex
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Mechanism caffeine in relation to increased alertness
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blockade of adenosine receptors
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NonREM
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stages 1-4
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Sleep-promoting regions are postulated to be where?
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in the medullary reticular formation and nucleus soltarius
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galanin
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peptide that contributes to inhibitory pathway related to sleep
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Where are REM-on cells located
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pontine reticular formation
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Ventrolateral preoptic area (VPLO)
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promotes sleep during non-REM by inhibiting neurons involved in wakefulness; releases GABA and galanin
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Neurotransmitters which show progressive reduced firing during stages 1-4 of nonREM sleep and are silent during REM
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norepinephrine and serotonin
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Neuropeptide which is increased during REM sleep
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ACh
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PGO (ponto-geniculo-occipital) waves
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intermittent waves of activation passing from pons to thalamus to cortex thought to induce the visual imagery of dreams and assocaited with rapid eye movements
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glutamatergic REM-on cells
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located in the reticular formation; activate circuits involving inhibitory transmitter glycine in the medulla and spinal cord which inhibits lower motor neurons and accounts for decreased muscle tone during REM
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REM sleep behavioral disorder
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caused by lesions of glutamatergic REM-on cell pathway; abolishes the normal inhibition of motor activity during REM
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Levels of near orexin neurons and melanin during sleep and wake state
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higher during sleep and lower during wake
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The suprachiasmatic nucleus of the hypothalamus
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receives retinal inputs and is crucial for setting circadian rhythms and synchronizing them with the light-dark cycle
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What are the four classical clinical findings of narcolepsy?
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1) Excessive daytime sleepiness 2) Cataplexy (Sudden loss of muscle tone from the awake state, often in response to an emotional stimulus) 2) Hypnagogic or Hypnopompic dreamlike hallucinations 4) Sleep paralysis
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What is a coma?
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Unarousable unresponsiveness in which the patient lies with eyes closed for a minimum of 1 hour. Cerebral metabolism is typically reduced by at least 50%.
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What causes a coma?
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Impaired function of the cerebral cortex and diencephalic-upper brainstem arousal systems. Most commonly from trauma or anoxia.
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Brain death
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extreme, irreversible coma; no evidence of forebrain or brainstem function, including no brainstem reflexes; only spinal cord refexes may persist
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EEG in brain death
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electrocerebral inactivity or a flat pattern less than 2mV in amplitude
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Coma vs. brain death
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In a coma, many simple or even complex brainstem reflex activities are present
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EEG in coma
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usually abnormal (a common theme is that it is usually monotonous with little variability over time); but it can show many different patterns, including large-amplitude slow waves, burst-suppression, triphasic waves, spindle waves, or even alpha activity
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What is a vegetative state?
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When patients regain sleep-wake cycles and other primitive orienting responses and reflexes mediated by the brainstem and diencephalon, but remain unconscious; patients may open their eyes or turn heads toward audition
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Persistent vegetative state
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conditions lasting more than 1 month
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Appearance of visual tracking may be the earliest sign of emergence into what?
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A minimally conscious state
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What do akinetic mutism, abulia, and catatonia have in common?
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circuits involving frontal lobes, diencephalon, and ascending dopaminergic projections important to the initiation of motor and cognitive activity
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What is akinetic mutism?
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The patient appears fully awake and visually track the examiner, but do not respond to any commands. The primary deficit is in motor initiation rather than in consciousness. Can be seen as an extreme form of abulia.
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The primary deficit in akinetic mutism is ___
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motor intuition, not consciousness
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What is abulia?
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Often resulting from frontal lobe lesions, in which the patients usually sit passively but may occasionally respond to questions or commands after a long delay.
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What treatment can reverse abulia and akinetic mutism in some patients?
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Dopaminergic agonists.
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What is catatonia?
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An akinetic state that can occasionally be seen in advanced cases of schizophrenia. Frontal-lobe and dopaminergic dysfunction have been implicated.
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status epilepticus
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continuous seizure activity
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Cause: Transient loss of consciousness
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caused by cardiac or other medical conditions, not usually neurological
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Most common causes of bilateral cerebral dysfunction
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global anoxia, metabolic/toxic disorders, head trauma, bilateral infarcts
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Common causes of brainstem dysfunction causing coma
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extrinsic compression from cerebral of cerebellar mass lesions or by intrinsic lesions (infarct, hemorrhage)
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Tx coma before labs
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IV thiamine, dextrose, naloxone (flumazenil if benzodiazepine overdose is suspected)
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Who shouldn't get IV thiamine, dextrose, and naloxone when suspected of a coma?
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Infants. They shouldn't be given dextrose unless they're hypoglycemic.
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Appearance of pupils: toxic and metabolic disorders
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normal (usually)
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Appearance of pupils: midbrain lesion or transtentorial lesion
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unilateral or bilateral "blown" pupil
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Appearance of pupils: pontine lesion
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small, responsive to light bilaterally
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Appearance of pupils: opiate overdose
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pinpoint pupils bilaterally
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Respiration rhythms are controlled by what?
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The medulla; voluntary control in the forebrain
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pre-Botzinger complex
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located in the medulla; pacemaker for respiration
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Lower motor neurons involved in respiration
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Cervical spinal segments C3-C5 (phrenic) contract the diaphragm during inspiration, while thoracic levels control thoracic inspiratory and expiratory muscles
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Ataxix respiration
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ominous pattern of very irregular breathing that may lead to respiratory arrest
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Lesions in the rostral pons can lead to a peculiar breathing pattern called what?
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Apneustic respiration
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Apneustic respiration
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the patient has brief 2- to 3- second respiratory pauses at full inspiration
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Midbrain lesions may lead to what type of respiration?
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Central neurogenic hyperventilation
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Where are the presympathetic neurons that maintain normal BP found?
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Rostral ventrolateral medulla
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Crescendo-decrescendo breathing is most likely caused by lesions where?
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Bilateral lesions at or above the upper pons
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What causes Cheyne-Stokes respiration?
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In bilateral lesions at or above the level of the upper pons, or in mountain climbers sleeping at high altitudes, or in medical conditions such as cardiac failure.
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What is Cheyne-Stokes respiration?
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When breathing becomes progressively deeper and then shallower to the point of apnea.
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The nucleus solitarious is important in what?
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Circulatory regulation and respiration; received inputs from baroreceptors in the carotid body and aortic artch via cranial nerves IX and X
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Inputs from the nucleus soltarius to __________ may be important in mediating emotinal responses to altered cardiorespiratory function and have been postulated to play a role in triggering panic attacks
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limbic system
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What functions are heavilty dependent on circuits in the pontomedullary reticular formation?
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Coughing, hiccuping, sneezing, yawning, shivering, gagging, vomiting, swallowing, laughing and crying.
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What and where is the area postrema?
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Located on the lateral wall of the fourth ventricle in the medulla. It contains a chemotactic trigger zone where the blood-brain barrier is incomplete. Allows endogenous and exogenous to trigger nausea and vomitting.
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___ (neurotransmitter) release from stomach/SI cells also cause nausea/vomiting because this neurotransmitter stimulates afferents traveling with the vagus to reach the ___ in the brainstem.
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5-HT
nucleus solitarius |
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sphincter control
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pontine micturation center and other regions of the reticular formation
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The periaqueductal gray matter functions with other regions in the brainstem to do what?
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modulate pain transmission.
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Where does blood to the posterior fossa come from?
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Vertebrobasilar system.
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What is the last cervical vertebra through which the vertebral arteries ascend before piercing the dura to enter the foramen magnum?
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C2
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The vertebral arteries enter the cranial cavity through the ________
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foramen magnum
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The paired vertebral arteries join to form a single _________ artery
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basilar
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The basilar artery splits at the _______ to form two _________
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pontomesencephalic junction; posterior cerebral arteries
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The PICA arises from the vertebral artery at the level of what?
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the medulla, and wraps around to supply the lateral medulla and inferior cerebellum.
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The AICA arises from the proximal basilar artery at the level of?
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The caudal pons and supplies the lateral caudal pons and a small region of the cerebellum.
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The SCA arises from the top of the basilar artery at the level of the rostral pons and supplies the what?
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Superior cerebellum as well as a small region of the rostral lateral dorsal pons.
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What cranial nerve passes between the SCA and the PCA?
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CN III Oculomotor.
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The PCA arises from the top of the basilar artery and supplies what?
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The midbrain, most of the thalamus, medial occipital lobes, and inferior-medial temporal lobes.
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Blood supply of medial medulla
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paramedian branches of the anterior spinal artery in more caudal regions and by paramedian branches of the vertebral arteries in more rostal regions
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The anterior spinal artery supplies what?
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The medial medulla caudally, by paramedian branches.
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Blood supply lateral medulla
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penetrating branches of the vertebral artery and the PICA
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Blood supply medial pons
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branches of the basilar artery
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Blood supply lateral pons
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circumferential branches of the basilar artery and AICA
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The inner ear is supplied by what?
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The internal auditory (labyrinthe) artery. From the AICA (occasionally will branch off of basilar artery)
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Blood supply rostral pons
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lateral pontine arteries (branches of basillar)
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Blood supply superior dorsolateral pons
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SCA
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Blood supply midbrain
|
penetrating branches arising from the top of the basillary artery and from the proximal PCAs
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Blood supply thalamus
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top of the basilar artery and proximal PCA
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Arteries of Percheron
|
anatomic variation in the brain vascularization in which a single arterial trunk arises from the posterior cerebral artery (PCA) to supply both sides of brain structures; the thalamus and midbrain
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Contralateral/one-sided/crossed sign symptoms are commonly more indicative of...
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brainstem involvement rather than cerebral
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Aphasia, hemineglect, hemianopia, and seizures indicate...
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hemispheric involvement rather than brainstem
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midbrain dysfunctions include...
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CN3 palsy, pupil dilation, ataxia, flexor posturing, impaired consciousness
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pons dysfunction....
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unilateral Babinski, weakness, perioral numbness, tingling face, bilateral upper or lower visual loss/blurring, irregular respirations, ocular bobbing, shivers, palatal myoclonus, abducens palsy, horizontal gaze palsy, small but reactive pupils
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medullary dysfunction...
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vertigo, ataxia, nystagmus, nausea, vomit, resp arrest, autonomic instability, hiccup
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How does atherosclerotic disease causing vertebral stenosis or basilar stenosis result in the brainstem?
|
Waxing and waning signs that may be sensitive to changes in BP
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Why is vertebral or basilar thrombosis life threatening?
|
potential widespread brainstem infarction
|
|
When should tPA therapy be given?
|
thrombosis events within 4.5 hours of onset
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After the window of tPA therapy, what should be given?
|
antiplatelet agents like aspirin
|
|
When is pontine hemorrhage most commonly seen?
|
chronic HTN
|
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What part of the midbrain contains the cortico-spinal tract?
|
basis
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|
Possible ischemic structures: Dizziness, vertigo, nausea
|
vestibular nuclei, cerebellum, or inner ear
|
|
Possible ischemic structures: diplopia, dysconjugate gaze
|
Supranuclear or Infranuclear eye movement pathways.
|
|
Possible ischemic structures: blurred vision or other visual disturbances
|
eye movement pathways; long sensory or motor tracts.
|
|
Possible ischemic structures: incoordination (ataxia)
|
cerebellum or cerebellar pathways
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|
Possible ischemic structures: unsteady gait
|
cerebellar pathways; long sensory or motor paths
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|
Possible ischemic structures: dysarthria, dysphagia
|
corticobulbar pathways or brainstem cranial nerve nuclei
|
|
Possible ischemic structures: numbness and tingling, particularly bilateral or perioral
|
Long somatosensory pathways or trigeminal system
|
|
Possible ischemic structures: hemiparesis, quadriparesis
|
corticospinal tract
|
|
Possible ischemic structures: somnolence
|
pontomesencephalic reticular formation or bilateral thalami
|
|
Possible ischemic structures: Occipital headache
|
Posterior fossa meninges and vessels (CN X and cervical roots)
|
|
Possible ischemic structures: frontal headache
|
Supratentorial meninges and vessels (CN V; PCA is often CN V1)
|
|
Possible ischemia structures: nonlocalized headache
|
supra- and/or infratentorial meninges and vessels
|
|
Crossed-signs and cranial nerve abnormalities are strongly suggestive of _____ involvement?
|
Brain-stem.
|
|
Aphasia, hemineglect, hemaniopia, and seizures are strongly suggestive of ____ involvement?
|
Hemispheric.
|
|
Signs of midbrain dysfunction
|
third-nerve palsy, unilateral or bilateral pupil dilation, ataxia, flexor (decorticate) posturing, and impaired consciousness
|
|
Signs of pontine dysfunction
|
b/l Babinski's signs, generalized weakness, periorbital numbness, "salt and pepper" facial tingling, bilateral upper or lower visual loss or blurring (usually caused by impaird blood flow from the basilar artery to both PCAs), irregular respirations, ocular bobbing, shivering, palatal myoclonus (affecting central tegmental tract), abducens palsy or horizontal gaze palsy, b/l small but reactive pupils, extensor (decerebrae) posturing, and impaired consciousness
|
|
Signs of medullary dysfunction
|
vertigo, ataxia, nystagmus, nausea, vomiting, respiratory arrest, autonomic instability, and hiccups
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|
Lateral medullary syndrome is usually caused by?
|
Vertebral thrombosis
|
|
Medial basis pontis infarcts are usually caused by?
|
Lacunar disease
|
|
Structures found and anatomical clinical features caused by ischemia/stroke in the medial medulla
|
Pyramidal tract (contralateral arm or leg weakness); medial lemniscus (contralateral decreased position and vibration sense), hypoglossal nucleus and exiting CN XII fasicles (Ipsilateral tongue weakness)
|
|
Medial medullary syndrome is caused by occlusion of what?
|
Paramedian branches of the anterior spinal or vertebral arteries.
|
|
What are the feautures of wallenberg/ lateral medullary syndrome?
|
Ipsilateral ataxia (inferior cerebellar peduncle), vertigo (vestibular nuclei), decreased pain and temperature sensation ipsilateral face (spinal trigeminal nucleus and tract) and of contralateral body ( spinothalmic tract). Horner's syndrome (descending sympathetic fibers).
|
|
Presence of hoarseness or loss of taste sensation helps localize a syndrome to what brain region?
|
Medulla. Hoarseness/Taste from the Nucleus ambiguus/Nucleus Solitarius.
|
|
Ipsilateral hearing loss suggests ____ involvement rather than lateral medullary syndrome.
|
AICA involvement.
|
|
Dysarthria hemiparesis (pure motor hemiparesis): region and vascular supply
|
medial pontine basis; paramedian branches of basilary artery, ventral territory
|
|
Dysarthria hemiparesis (pure motor hemiparesis): affected structures and clinical features
|
corticospinal and corticobulbar tracts (contralateral face, arm, and leg weaknss)
|
|
Ataxic hemiparesis: region and vascular supply
|
medial pontine basis; paramedian branches of basilary artery, ventral territory
|
|
Ataxic hemiparesis: affected stuctures and clinical features
|
corticospinal and corticobulbar tracts (contralateral face, arm, and leg weaknss)
|
|
Foville's syndrome: region and vascular supply
|
Medial pontine basis and tegmentum; paramedian branches of basilar artery, ventral and dorsal territories
|
|
Foville's syndrome: affected structures and clinical features
|
corticospinal and corticobulbar tracts (contralateral face, arm, and leg weaknss); facial colliculus (ipsilateral facial weakness, ipsilateral horizontal gaze palsy)
|
|
Pontine wrong-way eyes: region and vascular supply
|
Medial pontine basis and tegmentum; paramedian branches of basilar artery, ventral and dorsal territories
|
|
Pontine wrong-way eyes: affected structures and clinical features
|
corticospinal and corticobulbar tracts (contralateral face, arm, and leg weakness; dysarthria); abducens nucleus or paramedian pontine reticular formation (ipsilateral horizontal gaze palsy)
|
|
Millard-Gubler syndrome: region and vascular supply
|
Medial pontine basis and tegmentum; paramedian branches of basilar artery, ventral and dorsal territories
|
|
Millard-Gubler syndrome: affected structures and clinical features
|
corticospinal and corticobulbar tracts (contralateral face, arm, and leg weakness; dysarthria); facicles of facial nerve (ipsilateral facial weakness)
|
|
AICA syndrome: region and vascular supply
|
lateral caudal pons; AICA
|
|
AICA syndrome: affected structures and clinical features
|
middle cerebellar peduncle (ipsilateral ataxia); vestibular nuclei (vertigo, nystagmus); trigeminal nucleus and tract (ipsilateral facial decreased pain and temperature sense); spinothalamic tract (contralateral body decreased pain and temperature sense); Descending sympathetic fibers (ipsilateral Horner's)
|
|
Ischemia to the labyrinthe artery causes what clinical features? Where is this artery located?
|
ipsilateral hearing loss; lateral caudal pons
|
|
SCA syndrome: region and vascular supply
|
dorsolateral rostral pons; SCA
|
|
SCA syndrome: affected structures and clinical features
|
superior cerebellar peduncle and cerebellum (ipsilateral ataxia); other lateral tegmental structures (variable features)
|
|
Weber's syndrome
|
Occurs in the midbrain basis; branches of PCA and top of basilar artery; affects oculomotor nerve fasicles causing ipsilateral third nerve palsy and the cerebral peduncle causing contralateral hemiparesis
|
|
Claude's syndrome
|
Occurs in the midbrain tegmentum; branches of the PCA and top of basilar artery; affects oculomotor nerve fascicles causing ipsilateral third nerve palsy and red nucleus, superior cerebelllar peduncle fibers causing contralateral ataxia
|
|
Benedikt's syndrome
|
Occurs in the midbrain basis and tegmentum; branches of the PCA and top of basilar artery; affects oculomotor nerve fascicles (3rd nerve palsy), cerebral peduncle (contralateral ataxia), and red nucleus, substantia nigra, and superior cerebellar peduncle (contralateral ataxia, tremor, and involuntary movements)
|
|
Cause: Top-of-the-basilar syndrome
|
embolus that lodges the distal basilar artery
|
|
Clinical features: Top-of-the-basilar syndrome
|
visual disturbances resulting from infarcts of the visual cortex; memory disturbances from infarcts ofthe bilateral medial thalami or temporal; eye movements from oculomotor nuclei; somnolence, delirium, and vivid hallucinations
|
|
Basilar scrape syndrome
|
embolus that migrates up the basilar artery toward the top; it occludes various penetrator arteries in the pons
|
|
What is Millard-Gubler syndrome?
|
Occlusion of paramedian branches of basilar artery, ventral and dorsal territories. Affectiong the Corticospinal and corticobulbar tracts (in the pons), leading to contralateral face, arm, and leg weakness; dysarthria.
|
|
Midbrain basis vascular syndrome is called?
|
Weber's syndrome. Branches of PCA and top of basilar artery. Oculomotor nerve fascicles affected. Ipsilateral 3rd nerve palsy. Cerebral peduncle. Contralateral hemiparesis.
|
|
Midbrain tegmentum vascular syndrome?
|
Claude's syndrome. Branches of PCA and top of basilar artery. Oculomotor nerve fascicles and third-nerve palsy. Red nucleus/ superior cerebellar peduncle fibers. Contralateral ataxia.
|
|
Midbrain basis and tegmentum vascular syndrome is called?
|
Benedikt's syndrome. Branches of PCA and top of basilar artery. Oculomotor nerve fascicles, Cerebral peduncle, Red nucleus, substantia nigra, superior cerebellar peduncle fibers.
|
|
Features of Benedikt's syndrome?
|
Ipsilateral third-nerve palsy. Contralateral hemiparesis. Contralateral ataxia, tremor, involuntary movements.
|