Ventral posterolateral nucleus of the thalamus (third-order neurone) and thalamocortical radiation
Third-order neurone / LMN · contralateral all modalities
Both the medial lemniscus and the spinothalamic tract end in the VPL, while the face arrives in the adjacent ventral posteromedial nucleus. Third-order neurones project through the posterior limb of the internal capsule as the thalamic radiation to the postcentral gyrus, so all sensation from the contralateral body converges here.
Traced from the start
- Cutaneous mechanoreceptors (Meissner, Pacinian, Merkel, Ruffini)Proprioceptors (muscle spindle, Golgi tendon organ, joint receptors)
- Fasciculus gracilis (medial dorsal column)Fasciculus cuneatus (lateral dorsal column)
- Nucleus gracilis and cuneatus to internal arcuate fibres (sensory decussation, caudal medulla)
- Nociceptors and thermoreceptors (free nerve endings)
- Dorsolateral tract of Lissauer and dorsal horn synapse (Rexed laminae I, II and V)
- Anterior (ventral) white commissure
- Medial lemniscusLateral spinothalamic tract (anterolateral system)Anterior spinothalamic tract (crude touch and pressure)
- Ventral posterolateral nucleus of the thalamus (third-order neurone) and thalamocortical radiation
Detail
- Inputs
- Medial lemniscus and spinothalamic tract (body); trigeminal lemniscus to VPM (face)
- Output
- Thalamic radiation via the posterior limb of the internal capsule to the postcentral gyrus
- Blood supply
- Thalamogeniculate branches of the posterior cerebral artery
When it goes wrong
Thalamic (VPL) lacunar infarct or haemorrhage
Contralateral hemianaesthesia to all modalities including the face, without weakness (pure sensory stroke)
Dejerine-Roussy thalamic pain syndrome, weeks after a thalamic stroke
Severe spontaneous burning pain and allodynia in the numb contralateral side
Practise this structure
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