Download subcortical white matter (centrum semiovale)

dispersion of internal capsule
as the corona radiata ►
▲ optic radiation
auditory radiation ►
subcortical white matter
(centrum semiovale)
- projection tracts
- axonal tracts connecting the brain
to or from the ‘outside’ of the brain
- internal capsule
- projection tracts between the cerebral cortex, and thalamus and spinal cord
- in horizontal cross-section, internal capsule is a V-shaped collection of
axonal tracts, with the angle of the ‘V’ (the “genu”) pointing medially,
separating the lenticular nucleus (globus pallidus and putamen) (laterally)
from the caudate nucleus (located medially and anteriorly) and also from
the thalamus (located medially and posteriorly)
- located posterior to the genu are corticobulbar tracts from the motor cortex to
cranial nerve motor nuclei in brainstem and corticospinal tracts in spinal cord
- located both anterior and posterior to corticobulbar and corticospinal tracts
in internal capsule are corticopontinecerebellar tracts from premotor/motor
cortex, and other cortex, to cerebellum (via cerebral peduncles, then pons)
- thalamocortical tracts go to sensory cortex from thalamus neurons receiving
synapses from neurons in spinothalamic tracts and dorsal columns
- note: tracts from the most posterior thalamic nuclei are not in
the internal capsule, but go under lenticular nucleus:
- medial geniculate nucleus (of thalamus) →
→ auditory radiation →
→ auditory cortex
- lateral geniculate nucleus (of thalamus) →
→ optic radiation →
→ visual cortex
(continued, next page)
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