thalamus Flashcards
hypothalamus
limbic system, neuroendocrine function, autonomic nervous system
epithalamus
pineal gland
habenula (limbic system)
subthalamus
subthalamic nuclei involved with motor control
zone incerta
thalamus
numerous nuclei (grey matter)
most have extensive reciprocal connections within the cerebral cortex
anatomy of the thalamus
located in the diencephalon
egg shaped collection of nuclei
on top of the brainstem
forms the wall of the third ventricle
separated from the hypothalamus by the hypothalamic sulcus
what nerve fibres surround the thalamus?
posterior limb of the internal capsule
stria medullaris
stria terminallis (between thalamus and caudate nucleus)
what are the two thalami connected by?
interthalamic adhesion (massa intermedia)
internal organisation of the thalamus
thin layer of y-shaped afferent and efferent nerve fibres called the internal medullary lamina (white matter)
what does the internal medullary lamina divide the thalamus into?
three nuclear masses: anterior, medial and lateral
what nuclei are embedded into the internal medullary lamina?
intralaminar nuclei
what nuclei wrap around the outside of the thalamus?
reticular nuclei
relay of thalamic nuclei
majority project to ipsilateral cortex
- whole cortex receives input from the thalamus
- extensive reciprocal connections to the thalamus (corticofugal fibres)
classification of thalamic nuclei
specific, association and non-specific nuclei
what are specific thalamic nuclei?
general and special sensory information- sensory cortical regions
motor information- cerebellum, basal ganglia and frontal lobe
what are association thalamic nuclei?
input from specific cortical areas and project to associatio areas
regulate activity
what are non-specific thalamic nuclei?
associative areas of the cortex and brainstem
involved in arousal and alertness
what are the specific (relay) nuclei?
sensory and motor connections located in the lateral nuclear group (ventral part only)
-ventral anterior
-ventral lateral
-ventral posterior (lateral/medial)
-lateral geniculate body
-medial geniculate body
what are the two types of ventral posterior nuclei?
ventral posterolateral (VPL) and ventral posteromedial (VPM)
input and output of ventral posterior nuclei
ascedning pathways from spinal cord and brainstem
general sensory information from contralateral body and face
which projects to the somatosensory cortex
information in VPL
limbs and trunk
information in VPM
face and head (trigeminal nerve)
taste information (nucleus solitarius in medulla)
vestibular information (vesitbular nuclei)
where are the geniculate nuclei?
pole of the thalamus
lateral geniculate nuclei information
visual system
optic tract reticular ganglion cells
visual information from ipsilateral temporal hermirentina and contralateral nasal retina
projects to the primary visual cortex via optic radiation
medial geniculate nuclei information
auditory information
ascedning fibres from inferior colliculus
projects to the primary auditory cortex via auditory radiation
ventral anterior and ventral lateral nuclei information
fibres from basal nuclei (globus pallidus and substantia nigra)
- ventral lateral nuclei fibres from cerebellum
- both project to premotor and motor cortex
- influence normal movement
- mediate abnormalities in motor disorders
what are the nuclei of the association nuclei?
pulvinar
anterior
medial
pulvinar nuclei information
largest association nuclei
afferents from superior colliculus and association cortex
projects to secondary visual areas and association areas of parietal, temporal and occipital lobes
high order visual function- visual perception and eye movements
what nuclei are in the anterior nuclei?
lateral dorsal
lateral posterior
anterior nuclei information
afferent project from the mammillary bodies of the hypothalamus
projects to the cingulate gyrus
function not entirely clear (limbic system)
- control of instinctive drives
- emotional learning
- emotional aspects of behaviour
lateral dorsal nuclei
expression of emotions
lateral posterior nuclei
intergrate visual/sensory input into cognitive functions
what nuclei are in the medial nuclei?
dorsomedial/mediodorsal nucleus
medial nuclei information (lateral)
inputs from the superior colliculus, olfactory cortex and the ventral pallidum
projects to the frontal eye fields and cingulate cortex (frontal lobe)
involved in controlling eye movements and attending to visual stimuli
medial nuclei information (medial)
inputs from several brain regions (include solitary nucleus, substantia nigra, amygdala)
what does the medial nuclei control?
mood and emotions
what two nuclei are within the non-specific nuclei?
reticuluar thalamic nucleus and intralaminar nuclei
reticular thalamic nucleus information
thin nuclei layer between the external medullary lamina and the internal capsule
inputs from reticular formation (brainstem), cerebral cortex and thalamus
strong inhibitory output to thalamic nuclei
may regulate signals relaying through the thalamus
important in sleep wake cycles and selective attention
intralaminar nuclei
embedded within the internal medullary lamina
inputs from reticular formation, spinothalamic and trigeminothalamic systems
project to widespread cortical regions and basal nuclei
activates the cortex and disrupt alpha brain rhythm (sleep)
involved in arousal and alertness
