Thalamus Flashcards
Nuclear groups of the thalams
Anterior Medial (Dorsomedial) Lateral Posterior Intralaminar Other
Anterior Nuclear Group
Anterior Nucleus:
afferents: Mammilothalamic tract, Hippocampal afferents via fornix
efferents: To Cingulate Gyrus
Medial Nuclear Group
Dorsomedial nucleus
Amygdala and Olfactory Cortex –> DM –> Prefrontal cortex
Sub. Nigra pars Reticulata –> DM –> Frontal Eye feilds in Middle frontal gyrus. (Brodman 8)
Posterior Nuclear Group
Pulvinar - Lateral Geniculate - Medial Geniculate
Pulvinar connections
Association cortices –> Pulvinar –> Diffuse cortex projections
Retina –> Pulvinar –> Visual Association Cortex V2, V3
Superior Colliculus –> Pulvinar –> Visual Association Cortex, extrastriate cortices)
Both of the above are Extrageniculate Ocular Pathways
Reticular Nucleus connections
Interthalamic connections, Reticular Nucleus links thalamic nuclei to one another.
It also recieves diffuse cortical afferents.
Lateral Geniculate body connections
Retinal Ganglion cells –> LGB –> Primary visual cortex
Ipsilateral fibers (from ipsilateral temporal visual field) go to layers 2,3,5 Contralateral fibers (from contralateral nasal visual field) go to layers 1,4,6
Medial Geniculate body connections
Inferior Colliculus –> MGB –> Primary Auditory cortex and Secondary auditory cortex B41 and B42.
Lateral Nuclear Group
Lateral Dorsal Nucleus - LD Lateral Posterior Nucleus - LP Ventral Anterior - VA Ventral Lateral - VL Ventral Posteromedial - VPM Ventral Posterolateral - VPL
Ventral Anterior Nucleus connections
Medial Globus Pallidus and Sub. Nigra pars reticulata –> VA –> Premotor Cortex.
ARAS –> Intralaminar Thalamic Nuclei –> VA –> Diffuse Frontal Projections
Intralaminar Nuclei connections
ARAS –> Rostral Intralaminar Nuclei –> VA thalamic nucleus
Ventral Lateral Nucleus connections
Output nuclei of basal ganglia —> VL anterior portion –> Supplementary Motor Cortex
Contralateral Deep Cerebellar Nuclei –> VL posterior portions –> Premotor Cortex and Primary Motor Cortex.
Lateral Dorsal Nucleus connections
Limbic lobe and Parietal region –> LD –> Cigulate Gyrus and Medial Parietal Cortex
Lateral Posterior Nucleus connections
Superior Parietal Lobule –> LP –> Superior Parietal Lobule
Ventral Postero Lateral Nucleus connections
Medial Lemniscus and Spinothalamic Tract –> VPL –> Primary and Secondary Somatosensory Cortex.
Ventral Postero Medial Nucleus connections
Principle Sensory Nucleus of Trigeminal Nerve and the Spinal Trigeminal Nucleus (Dorsal Trigeminal Nucleus) => Trigeminal lemniscus
–>
VPM –> Primary Secondary Somatosensory Cortex
Nucleus of Solitary Tract (STN) –> VPM parvocellular cells –> Parietal Operculum taste area Brodman 43.
*The VPM/VPL has a somatotopic organization of corresponding neurons relaying the sensory afferents
What are the intralaminar nuclei?
The Rostral Intralaminar Nuclei, don't need names and the Caudal Intralaminar Nuclei: 1) the Parafascicular Nucleus 2) the Centromedian Nucleus
Rostral Intralaminar Nuclei connections
Association cortices –> Pulvinar –> Diffuse cortex projections
Caudal Intralaminar Nuclei connections
Medial/Internal Globus Pallidus –> Centromedian Nucleus (CM) –> Putamen and diffuse cortical
Median/Internal GP –> Parafascicular (PF) –> Caudate and diffuse cortical
What are the major functional classifications of the thalamic nuclei?
Sensory Relay nuclei: VPL VPM, Lateral and medial geniculates.
Association nuclei: Dorsomedial Nuclei, Lateral Dorsal Nucleu, Lateral Posterior Nucleus, Pulvinar
Non-specific/diffuse nuclei: Midline and intralaminar nuclei
Nuclei not projecting to the cortex: Reticularis Nucleus, Parafascicularis, Subparafascicularis.
