CT Brain Anatomy
White matter structures

Key points

  • The internal capsules and corpus callosum are clinically important white matter tracts

White matter of the brain lies deep to the cortical grey matter.

The internal capsules are white matter tracts which connect with the corona radiata and white matter of the cerebral hemispheres superiorly, and with the brain stem inferiorly.

The corpus callosum is a white matter tract located in the midline. It arches over the lateral ventricles and connects white matter of the left and right cerebral hemispheres.

Internal capsules - CT brain

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Internal capsules

  • The internal capsules are narrow white matter tracts which contain a high number of axons connecting the corona radiata and cerebral hemisphere white matter superiorly to the brain stem inferiorly
  • Each internal capsule has an anterior limb and a posterior limb connected at the 'genu' (asterisks)

Internal capsule - clinical significance

  • The internal capsules are supplied by perforating branches of the middle cerebral arteries
  • As these vessels are small they are susceptible to lacunar infarcts
  • Even a small insult to the internal capsule can have a profound affect on motor and sensory function

Corpus callosum - CT brain - sagittal image

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Corpus callosum

  • Sagittal CT images show the corpus callosum as a midline structure arching from anterior to posterior

Corpus callosum and corona radiata - CT brain

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Corpus callosum and corona radiata

  • Superior to the internal capsule the white matter widens out into the corona radiata and then into the white matter of the cerebral hemispheres
  • The corona radiata of each side is interconnected via the corpus callosum
  • The anterior part of the corpus callosum is called the genu and the posterior part is called the splenium

Corpus callosum - clinical significance

  • Malignant lesions of the brain can grow from one brain hemisphere to the other via the corpus callosum
  • Elsewhere the falx acts as a relative barrier to direct invasion