The Thalamus
What arteries supply the anterior limb of the internal capsule?
Medial striate branches of anterior cerebral artery Lateral striate branches of middle cerebral artery
To where does the ventral lateral nucleus project?
Motor cortex (area 4) Supplementary motor cortex (SMA, area 6)
The pulvinar has reciprocal connections with what areas?
Association cortex of occipital, parietal, and posterior temporal lobes
What is the function of the medial geniculate nucleus?
Auditory relay nucleus
What arteries supply the genu of the internal capsule?
Direct branches from internal carotid artery OR Pallidal branches of anterior choroidal artery
What is the function of the mediodorsal nucleus?
Affect, emotion, and behavior
From what structures does the mediodorsal nucleus of the thalamus receive input?
Amygdaloid nucleus Temporal neocortex Substantia nigra
What arteries supply the posterior limb of the internal capsule?
Anterior choroidal artery Lenticular branches of middle cerebral artery
What are the 3 parts of the internal capsule?
Anterior limb Genu Posterior limb
The anterior limb of the internal capsule separates what structures?
Caudate nucleus and lentiform nucleus
What is the largest intralaminar nuclei?
Centromedian nucleus
To where does the anterior nucleus of the thalamus project?
Cingulate gyrus
To where does the lateral dorsal nucleus project?
Cingulate gyrus
What are the manifestations of thalamic syndrome?
Contralateral hemiparesis Contralateral hemianesthesia Elevated pain threshold Spontaneous, agonizing, burning pain (hyperpathia, dysaesthesia, allodynia) Athetotic posturing of hand
What are the manifestations of ligation of the anterior choroidal artery?
Contralateral hemiparesis Contralateral reduction of rigidity
What are the manifestations of a lesion to the ventral posteromedial nucleus?
Contralateral loss of pain and temperature sensations Tactile discrimination in head Ipsilateral loss of taste
What are the manifestations of a lesion to the ventral posterolateral nucleus?
Contralateral loss of pain and temperature sensations Tactile discrimination in the trunk and extremeties
What are the manifestations of an infarction of the internal capsule?
Contralateral tactile hypoesthesia COntralateral anesthesia Contralateral hemiparesis Contralateral lower facial weakness Contralateral homonymous hemianopia
What are the 4 main functions of the thalamus?
Convergence of afferent sensory impulses Sorting and filtering of similar impulses Relaying impulses on to cerebral cortex Mediation of sensation, motor, cortical arousal, learning, and memory
What fibers are contained within the genu of the internal capsule?
Corticobulbar fibers
What fibers are contained within the anterior limb of the internal capsule?
Frontopontine (corticofugal) fibers Thalamocortical fibers
From where does the centromedian nucleus receive input?
Globus pallidus
From where does the ventral anterior nucleus receive input?
Globus pallidus Substantia nigra
From where does the ventral lateral nucleus receive input?
Globus pallidus Substantia nigra Cerebellum
What structure projects to the medial geniculate nucleus?
Inferior colliculus
What is the function of the ventral lateral nucleus?
Influencing somatic motor mechanisms
What connect the 2 thalami?
Intermediate mass
What tract runs into the lateral dorsal nucleus?
Mammillothalamic tract
From what structures does the pulvinar receive fibers?
Lateral geniculate nuclei Medial geniculate nuclei Superior colliculus
From what 2 structures and via what 2 tracts does the anteriro nucleus of the thalamus recieve input?
Mammilary nucleus via mammillothalamic tract Hippocampus via fornix
What is the most common cause of thalamic syndrome?
Occlusion of a posterior thalamo-perforating artery
What is the most common cause of an infarction of the internal capsule?
Occlusion of the lenticulostriate branches of the middle cerebral artery
What manifestation is associated with destruction of the ventral lateral nucleus?
Parkinsonian tremor
What 3 arteries supply the thalamus?
Posterior communicating artery Posterior cerebral artery Anterior choroidal artery
To where does the ventral anterior nucleus project?
Prefrontal and orbital cortices, diffusely Premotor cortex (area 6)
To where does the medial geniculate nucleus project?
Primary auditory cortex (areas 41, 42)
To where does the lateral geniculate nucleus project?
Primary visual cortex (area 17)
What is the function of the lateral geniculate nucleus?
Relaying visual information
The intralaminar nuclei receive input from what structures?
Reticular formation Ascending reticular system
What fibers are contained within the posterior limb of the internal capsule?
Sensory radiations Corticospinal fibers Visual and auditory radiations
To where does the ventral posteroinferior nucleus project?
Somatosensory cortex
To where does the ventral posterolateral nucleus project?
Somatosensory cortex (areas 3, 1, 2)
To where does the ventral posteromedial nucleus project?
Somatosensory cortex (areas 3, 1, 2)
What tracts does the ventral posterolateral nucleus receive?
Spinothalamic tracts Medial lemniscus
To where does the centromedian nucleus project?
Striatum Neocortex
To where does the parafascicular nucleus project?
Striatum Supplementary motor cortex (SMA, area 6)
The lateral posterior nucleus connects to what structure?
Superior parietal cortex (areas 5, 7)
The posterior limb of the internal capsule separates what structures?
Thalamus and lentiofrm nucleus
What tract does the ventral posteromedial nucleus receive?
Trigeminothalamic tract
What are the nuclei and subnuclei of the ventral tier of the thalamus?
Ventral anterior nucleus Ventral lateral nucleus Ventral posterior nuclei: VPL, VPM, VPI
What structures project to the ventral posteroinferior nucleus?
Vestibular nuclei
What condition is associated with destruction of the mediodorsal nucleus?
Wernicke-Korsakoff syndrome
What condition is associated with thiamine (vitamin B1) deficiency?
Wernicke-Korsakoff syndrome
