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Anterior limb of internal capsule

The anterior limb of the internal capsule is a critical white matter structure within the brain, acting as a major conduit for neural signals between the cerebral cortex and subcortical regions. Located between the head of the caudate nucleus medially and the lentiform nucleus laterally, this region plays a vital role in motor, sensory, and cognitive functions by transmitting thalamocortical and corticothalamic fibers. Its imaging characteristics and vascular supply are clinically significant in various neurological conditions.

Synonyms

  • Anterior crus of the internal capsule

  • Front limb of internal capsule

Anatomical Description

  • Positioned between the head of the caudate nucleus (medially) and the lentiform nucleus (laterally)

  • Forms part of the internal capsule, a major white matter tract

  • Separates the caudate nucleus from the putamen

Arterial Supply

  • Supplied primarily by the lenticulostriate branches of the middle cerebral artery (MCA)

  • Additional supply from the recurrent artery of Heubner (branch of the anterior cerebral artery)

  • Occasionally receives small branches from the anterior choroidal artery

Venous Drainage

  • Drained mainly by medullary veins

  • These veins ultimately drain into the deep cerebral veins (internal cerebral vein and basal vein of Rosenthal)

Function

  • Transmits frontopontine fibers (frontal cortex to pons)

  • Carries anterior thalamic radiations (thalamus to prefrontal cortex)

  • Involved in regulation of cognition, emotion, and some aspects of movement

  • Damage can result in cognitive and executive dysfunction

MRI Appearance

  • T1-weighted images: Appears bright (hyperintense) relative to surrounding gray matter

  • T2-weighted images: Appears dark (hypointense) compared to surrounding structures

  • FLAIR sequences: Remains dark (hypointense), helps distinguish it from pathological hyperintensities

CT Appearance

  • Appears as a slightly hypodense (darker) linear region compared to surrounding gray matter

  • The white matter of the anterior limb is less dense than the adjacent nuclei

  • May become less distinct in cases of edema, infarction, or demyelination

MRI images

Anterior limb of internal capsule mri 3t axial image

MRI images

Anterior limb of internal capsule mri 3t coronal image