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What are the nuclei located in the midbrain and their associated cranial nerve?
- oculomotor nucleus (motor of III)
- Edinger Westphal (PSNS of III)
- Colliculi/Pretectal Nuclei
- Trochlear nucleus (motor of IV)
- Red Nucleus
- Substantia Nigra
- Mesencephalic Nuclei (sensory of V)
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What are the nuclei located in the pons and their associated cranial nerve?
- Motor V, PrV, MesV, SpV
- Abducens nuclei (motor VI)
- Facial nucleus (motor of VII)
- Superior salivatory nuclei (PSNS of VII)
- Cochlear nuclei (special hearing of VIII)
- Vestibular nuclei (special balance of VIII)
- Pontine nucleus
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What are the nuclei located in the medulla and their associated cranial nerve?
- Inferior salivatory nuclei (PSNS of IX)
- Nucleus Ambiguus (motor of IX & X)
- Hypoglossal nuclei (motor of XII)
- Accessory nuclei (motor (XI)
- Vestibular nuclei (special balance of VIII)
- Solitary nuclei
- Spinal Trigeminal (sensory of V)
- Inferior olivary nuclei
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What lies in the basis?
- (anterior 1/3 of BS)
- corticofugal pathways
- motor nuclei (substantia nigra, pontine)
- pontocerebellar pathways
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What lies in the tegmentum?
- (basis --> 4th ventricle)
- reticular formation
- sensory nuclei & ascending sensory tracts
- cranial nerve nuclei
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What is modulated by the reticular formation?
- pain
- muscle tone and reflexes
- autonomic functions (BP, respiration)
- arousal
- awareness
- attention
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What are the three major regions of the reticular formation?
- midline (raphe) nuclei
- medial zone of reticular formation
- lateral zone of reticular formation
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What does the midline raphe nuclei regulate and which are ascending and descending pathways?
- regulate pain: ascending
- regulate sleep and arousal: descending
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What is the motor regulated part of the parasagittal midline nuclei and what do they do?
- Medial reticulospinal tract: facilitates extensors
- Lateral reticulospinal tract: inhibits spinal motor neurons
- (also has autonomic regulation)
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What do the parasagittal lateral nuclei do?
- receive extensive sensory inputs from both ascending/descending pathways
- project to parasagittal medial nuclei for output/motor response
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What neurotransmitter does the ventral tegmental area use and for what purpose?
- dopamine
- motivation and decision making
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What neurotransmitter does the peunculopontine nucleus use and where does it project?
- acetylcholine
- projects to BS motor nuclei (VST, RST)
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What is the function of the locus ceruleus and medial reticular zone?
- regulates attention
- inhibits pain at SC level
- regulates autonomic function
- descending role in pain modulation
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What are the four general places for midline lesions?
- corticospinal tract
- corticobulbar tract
- medial lemniscus
- medial longitudinal fasciculus
- reticular formation
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What does a midline lesion interfere with in the corticospinal tract?
contralateral hemiplegia
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What does a midline lesion interfere with in the corticobulbar tract?
- cranial motor nerve symptoms
- mainly IV, VII, XI, XII
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What does a midline lesion interfere within in the medial lemniscus?
contralateral positional and vibratory sense loss
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What does a midline lesion interfere with in the medial longitudinal fasciculus?
ipsilateral loss of adduction and contralateral nystagmus
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What does a midline lesion interfere with in the reticular formation?
disruption of BP, GI, respiration, arousal, sleep and muscle tone
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Where can lateral lesions occur in either the pons or medulla?
- spinothalamic tract
- spinal nucleus and tract of V
- vestibular nuclei (in lower pons, upper medulla)
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Where can lateral lesions occur in the medulla only?
- nucleus ambiguus
- inferior cerebellar peduncle
- descending sympathetic pathway
- vagus nerve
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Where can lateral lesions occur in the pons only?
- middle cerebellar peduncle
- main sensory nucleus of V
- facial nerve
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What does a lateral lesion (pons & medulla) interfere with in the spinothalamic tract?
pain and tenperature sensation from the body (contralateral)
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What does a lateral lesion (pons & medulla) interfere with in the spinal nucleus and travt of V?
pain and temperature sensation from the face
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What does a lateral lesion (pons & medulla) interfere with in the vestibular nuclei?
control of head position and eye movement
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What does a lateral lesion (pons only) interfere with in the middle cerebellar peduncle?
smoothness of movement
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What does a lateral lesion (pons only) interfere with in the main sensory nucleus of V?
corneal reflex and discriminative touch infor from the face
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What does a lateral lesion (pons only) interfere with in the facial nerve?
control of mm of facial expression
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What does a lateral lesion (medulla only) interfere with in the nucleus ambiguus?
swallowing, vocalization
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What does a lateral lesion (medulla only) interfere with in the inferior cerebellar peduncle?
smoothness of movement
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What does a lateral lesion (medulla only) interfere with in the descending sympathetic pathway?
sympathetic control of face; causes Horner's syndrome
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What does a lateral lesion (medulla only) interfere with in the vagus nerve?
digestion, ability to slow HR
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What does a anteromedial lesion (medulla and pons) interfere with in the corticospinal tract?
fractionated movements
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What does a anteromedial lesion (medulla and pons) interfere with in the medial lemniscus?
discriminitive touch and loss of proprioception
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What does a anteromedial lesion (medulla) interfere with in the hypoglossal nuclei?
tongue movement
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What does a anteromedial lesion (pons) interfere with in the medial longitudinal fasciculus?
adduction of eye past midline during lateral gaze
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Where can anteromedial lesions occur in the pons or medulla?
- corticospinal tract
- medial lemniscus
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Where can anteromedial lesions occur in only the medulla?
hypoglossal nerve
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Where can anteromedial lesions occur in only the pons?
medial longitudinal fasciculus
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Where can anterior lesions occur in the midbrain?
- corticospinal tract
- frontopontine tracts
- oculomotor nerve
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What does an anterior lesion (midbrain) interfere with in the corticospinal tract?
control of fractionated movement, face may be involved
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What does an anterior lesion (midbrain) interfere with in the frontopontine tract?
defeecit should cause ataxia, but it's not visible because hemiparesis or hemiplegia prevents movement
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What does an anterior lesion (midbrain) interfere with in the oculomotor nerve?
ability to move eye medially, downward, upward; also causes drooping upper eyelid, dilated pupil
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Where can a tegmental lesion occur in the midbrain?
- oculomotor nerve
- medial lemniscus, trigeminothalamic, & spinothalamic tract
- superior cerebellar peduncle & red nucleus
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What does an tegmental lesion (midbrain) interfere with in the oculomotor nerve?
ability to move eye medially, downward, upward; also causes drooping upper eyelid, dilated pupil
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What does an tegmental lesion (midbrain) interfere with in the medial lemniscus, trigeminothalamic, & spinothalamic tract?
- discriminitve tactile
- conscious proprioception
- temperature and pain sensation from face and body
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