Organ
Thalamus
Reciprocal cortical connections for sensation, action and brain state
High-yield
VPL principally relays body somatosensation and VPM facial somatosensation; a specialized VPM region participates in taste. The lateral and medial geniculate nuclei serve vision and hearing. VA/VL regions connect basal-ganglia and cerebellar activity with motor cortex.
Overview
Each thalamus lies beside the third ventricle and contains many nuclei. The internal medullary lamina separates major anterior, medial and lateral groups. Thalamic circuits relay and modify sensory, motor and limbic information and help regulate arousal. Olfaction can reach its primary cortex before a thalamic relay, although later olfactory processing includes thalamic connections.
Reference facts
- Location
- Paired diencephalic structures beside the third ventricle; their superior surfaces contribute to the floor of the lateral-ventricular bodies.
- Parts
- Anterior, medial and lateral groups; midline and intralaminar nuclei; geniculate bodies; and a lateral reticular nucleus that regulates other thalamic nuclei.
- Blood supply
- Tuberothalamic branches usually arise from the posterior communicating artery; paramedian, inferolateral and posterior choroidal groups arise mainly from PCA. Branch patterns vary.
- Relations
- Internal capsule laterally, hypothalamic/subthalamic regions below, third ventricle medially and epithalamic/pineal structures posteriorly.
- Function
- Processes sensory, motor and limbic signals through reciprocal cortical connections and participates in attention, arousal and conscious state.
Clinical correlation
Some thalamic strokes cause opposite-sided sensory deficits followed by central neuropathic pain. An artery-of-Percheron variant can supply both paramedian thalami; its occlusion may cause bilateral infarction with altered alertness or cognition, sometimes with midbrain involvement.
Frequently asked questions
Where is the thalamus located?
Paired diencephalic structures beside the third ventricle; their superior surfaces contribute to the floor of the lateral-ventricular bodies.
What does the thalamus do?
Processes sensory, motor and limbic signals through reciprocal cortical connections and participates in attention, arousal and conscious state.
What are the parts of the thalamus?
Anterior, medial and lateral groups; midline and intralaminar nuclei; geniculate bodies; and a lateral reticular nucleus that regulates other thalamic nuclei.
What is the blood supply of the thalamus?
Tuberothalamic branches usually arise from the posterior communicating artery; paramedian, inferolateral and posterior choroidal groups arise mainly from PCA. Branch patterns vary.