Capsula interna

Horicontal

section through Telencephalon. Basal ganglia blue.

Internal

capsule • Human brain - lateral view - Ganzer Fall bei Radiopaedia

Al Kabbani, A. Human brain - lateral view. Case study, Radiopaedia.org. (accessed on 01 Nov 2022) https://doi.org/10.53347/rID-72871 • CC by-nc-sa 3.0 (modified)

Internal

capsule • Internal capsule fibers (Gray's illustration) - Ganzer Fall bei Radiopaedia

Hacking, C. Internal capsule fibers (Gray's illustration). Case study, Radiopaedia.org. (accessed on 01 Nov 2022) https://doi.org/10.53347/rID-95953 • CC by-nc-sa 3.0 (modified)

Insular

cortex • Basal ganglia location - Gray's anatomy illustration - Ganzer Fall bei Radiopaedia

Illustrations, G. Basal ganglia location - Gray's anatomy illustration. Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-36284 • CC by-nc-sa 3.0 (modified)

Basal ganglia

• Basal ganglia (Gray's illustration) - Ganzer Fall bei Radiopaedia

Hacking, C. Basal ganglia (Gray's illustration). Case study, Radiopaedia.org. (accessed on 22 Oct 2022) https://doi.org/10.53347/rID-82120 • CC by-nc-sa 3.0 (modified)

Radiopaedia • CC-by-nc-sa 3.0 • de

The internal capsule is a deep subcortical structure that contains a concentration of afferent and efferent white matter projection fibers. Anatomically, this is an important area because of the high concentration of both motor and sensory projection fibers . Afferent fibers pass from cell bodies of the thalamus to the cortex, and efferent fibers pass from cell bodies of the cortex to the cerebral peduncle of the midbrain . Fibers from the internal capsule contribute to the corona radiata.

Gross anatomy

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 :

anterior limb (anterior crus)
- lies between the head of the caudate nucleus medially and the lentiform nucleus laterally
- contains the anterior thalamic radiation and frontopontine fibers
genu
- lies medial to the apex of the lentiform nucleus
- contains corticonuclear fibers (previously called corticobulbar fibers)
posterior limb (posterior crus)
- lies between the thalamus medially and the lentiform nucleus laterally
- contains
  - corticospinal fibers lying in the anterior two-thirds of the posterior limb
    - fibers from anterior to posterior: arm, hand, trunk, leg, perineum
  - the middle thalamic radiation which contains somatosensory fibers from the ventral posterior thalamic nucleus
retrolentiform part
- lies behind the lentiform nucleus
- contains the
  - geniculocalcarine or optic radiation (from the lateral geniculate nucleus)
  - corticopontine fibers (parietopontine and occiptopontine fibers)
sublentiform part
- lies below the lentiform nucleus
- contains the
  - auditory radiations (from the medial geniculate nucleus)
  - temporopontine fibers

Blood supply

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 . In addition, the anterior choroidal artery from the internal carotid artery supplies the posterior limb and retrolentiform part of the internal capsule .