Internal capsule

The internal capsule is a deep subcortical structure that contains a concentration of white matter projection fibers. These fibers form the corona radiata. Anatomically, this is an important area because of the high concentration of both motor and sensory projection fibers 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 fibers (previously called corticobulbar fibers)
  • posterior limb (PLIC)
    • lies between the thalamus medially and the lentiform nucleus laterally
    • contains
      • corticospinal fibers lying in the anterior two-thirds of the posterior limb
      • the middle thalamic radiation which contains somatosensory fibers from the ventral posterior thalamic nucleus  
  • retrolentiform part
  • 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 and retrolentiform part of the internal capsule 3,4

  • best appreciated on axial images at the level of the insular cortex
  • appears relatively hypodense to surrounding basal ganglia structures
Anatomy: Brain
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Article information

rID: 29687
Section: Anatomy
Synonyms or Alternate Spellings:
  • PLIC
  • PLICs

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Cases and figures

  • Figure 1: human brain - lateral view
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  • Figure 2
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