Internal capsule

The internal capsule is a deep subcortical structure that contains a concentration of white matter projection fibres. These fibres form the corona radiata. Anatomically, this is an important area because of the high concentration of both motor and sensory projection fibres 1,2

The internal capsule is made up of five parts. These are the anterior limb, genu, posterior limb, retrolentiform and sublentiform parts of the internal capsule 1,2

  • anterior limb
  • genu
    • lies medial to the apex of the lentiform nucleus 
    • contains corticonuclear fibres (previously called corticobulbar fibres)
  • posterior limb
    • lies between the thalamus medially and the lentiform nucleus laterally
    • contains
      • corticospinal fibres lying in the anterior two-thirds of the posterior limb
      • the middle thalamic radiation which contains somatosensory fibres from the ventral posterior thalamic nucleus  
  • retrolentiform part
    • lies behind the lentiform nucleus 
    • contains the geniculocalcarine or optic radiation
  • sublentiform part
    • lies below the lentiform nucleus 
    • contains the auditory radiations

The blood supply of the internal capsule is variable but is commonly from small perforating branches of the middle cerebral artery and anterior cerebral artery. These include the lateral lenticulostriate arteries and the recurrent artery of Heubner respectively 3. In addition, the anterior choroidal artery from the internal carotid artery supplies the posterior limb of the internal capsule 3

CT
  • best appreciated on axial images at the level of the insular cortex
  • appears relatively hypodense to surrounding basal ganglia structures

Neuroanatomy
Share article

Article Information

rID: 29687
Section: Anatomy
Synonyms or Alternate Spellings:

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Figure 1
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.