Thalamus

Overview

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Introduction

  • Function
    • serves as a major sensory relay center which will ultimately reach the neocortex
    • central nervous system structures involved in motor movement can also synapse in the thalamus
      • these structures include
        • cerebellum
        • basal ganglia
  • Anatomy
NucleiCircuitry
Anterior nuclear groupInputmamillary body (via the mammillothalamic tract)Outputcingulate gyrus (part of Papez circuit)
Medial nuclear groupInputamygdalaprefrontal cortextemporal lobeOutputprefrontal cortexcingulate gyrusNuclei exampledorsomedial nucleusthiamine deficiency can result in degeneration of this thalamic nuclei
Ventral posterolateral (VPL) nucleusInputsensory information from the dorsal columns and spinothalamic tractdorsal columnspressurevibrationproprioceptionfine touchspinothalamicpain and temperaturecrude touchOutputprimary somatosensory cortex
Ventral posteromedial (VPM) nucleusInputsensory information of trigeminal and gustatory afferents (in other words, the face)Outputprimary somatosensory cortex
Ventral lateral (VL) nucleusInputglobus palliduscerebellar dendate nucleusOutputprimary motor cortex
Medial geniculate bodyInputinferior colliculus (in other words, hearing)Outputauditory cortex
Lateral geniculate body Inputoptic nerve (cranial nerve II)Outputprimary visual cortex
  • Clinical correlate
    • thalamic pain syndrome
      • patients can present with a burning sensation and allodynia
      • this is secondary to
        • a stroke affecting the thalamus
    • Wernicke encephalopathy 
      • a neurologic emergency secondary to thiamine deficiency which affects the
        • mamillary bodies (in almost all cases)
        • dorsomedial thalamus