Thalamus NF
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Created by:
Sbdrmle Plus on April 5, 2012
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Dr. Bales 4.3.12
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23 terms
Terms | Definitions |
|---|---|
 went potty | missed slides 1-6 |
| Thalamic Radiations | 1) Thalamocortical & corticothalamic fibers form a continuous fan 2) Subparts of the fan are thalamic peduncles 3) Thalamus utilizes both limbs of internal capsule to project & receive fibers, but specifically PLIC to directly move fibers in & out of thalamus |
| Thalamic Nuclei | 1) Reticular nucleus: sheetlike on outermost area 2) Lateral: just inside reticular nuclei & can be divided into subparts 3) Intralaminar nucleus: biggest nucleus of this area is the centromedian nucleus 4) Anterior nucleus: 5) Medial nucleus: 6) Midline nucleus: another sheet-like portion, closest to midline 7) A sheet of myelinated fibers obliquely bisects the thalamus into approximate medial and lateral groups (= internal medullary lamina ) which anteriorly bifurcates around an anterior nucleus |
| Pulvinar | slide 16 |
| Tiers | slides 14 & 15 & 17 |
| groupings | on slide 20 |
| Midline Nuclei | 1) Nonspecific 2) Visceral & emotional responses 3) Arousal (cortical excitability slide 21 |
| Centromedian Nuclei | 1) Nonspecific 2) Regulation of arousal & cortical activity |
| Dorsomedial Nuclei | 1) Associatve 2) affect, emotion, behavior, + interpretation, integration, & response to odor 3) Lesion may relieve anxiety states: affects of lesion of DM parallel those of prefrontal lobotomy (which indicates disruption of connections to thalamus) DM can regenerate after prefrontal lobotomy 4) Consistently damaged in chronic alcoholism accompanied by thiamine deficiency (Karsakoff's syndrome: medial degeneration of thalamus, including DM, effect include anterograde amnesia) |
| Pulvinar Nuclei | 1) Associative 2) Visual integration: interpretation & response |
| Lateral Posterior Nuclei | 1) Associative 2) Visual integration: interpretation & response |
| Anterior Nuclei | 1) Limbic relay 2) Relay in limbic circuits of emotion & memory |
| Lateral Dorsal Nuclei | 1) Limbic Relay 2) Limbic fxns including emotions |
| Ventral Anterior Nuclei | 1) Motor relay 2) mvmt planning |
| Ventral Lateral Nuclei | 1) Motor relay 2) Mvmt planning & control |
| Ventral Posterior Lateral Nuclei | 1) Sensory relay 2) tough, conscious proprioception, pain, temp from limbs & trunk 3) A lesion due to infarct here produces a syndrome with the least behavioral effects and the most specific effects: contralateral hemianaesthesia (VPM, VPL, internal capsule) & homonymous hemianopia (LGN) |
| Ventral Posterior Medial Nuclei | 1) Sensory relay 2) tough, conscious proprioception, pain, temp, taste all from head |
| Lateral Geniculate Nuclei | 1) Sensory relay 2) Relay in primary visual perception |
| Medial Geniculate Nuclei | 1) Sensory relay 2) Relay in primary auditory perception |
| Reticular Nucleus | 1) "Gate keeper" 2) Regulate thalamocortical-corticothalamic communication (thalamocortical and corticothalamic pathways pass through and communicate with the reticular nucleus via axon collaterals) 3) The reticular nucleus probably modulates (regulates) the exchange of information between the thalamus and cortex |
| Vascular Lesions | 1) Leading cause of thalamic problems 2) Thalamic blood supply comes from the arterial circle of Willis or its branches (thalamus lies posterosuperior to the circle of Willis) 3) Irrigated almost entirely by slender branches of the posterior part of the circle (mainly posterior communicating artery & the posterior cerebral artery) perforating from below (some arch around a penetrate from behind/above) 4) An important branch of the MCA to multiple structures is anterior choroidal a. (it courses back along the optic tract and may supply a part of the thalamus also supplies part of the lateral geniculate body) |
| Vascular Territories | 1) Vascular injection studies of basal nuclei reveal distinct territories that do not correlate with nuclear boundaries 2) Four arterial territories have been identified & include multiple differently functioning nuclei 3) Syndromes depend on number and size of vessels infarcted, nuclei affected (most thalamic lesions produce mixtures of effects) |
| Clinical Points | 1) Thalamic hemorrhage or infarction is a common type of stroke and the leading cause of thalamic lesions. 2) Effects depend on which vessel(s) is affected and the area supplied by the vessel(s) 3) Small, deep infarcts of penetrating aa. are called "lacunar" strokes 4) There seems to be a great range and variety of deficits. 5) There no named syndromes limited to specific nuclei 6) There is no specific test to localize a lesion to the thalamus, but now modern imaging allows the detection of infarcts in vivo |
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