Genu of internal capsule

The genu of the internal capsule is the angled region where the anterior and posterior limbs meet, forming the apex of the characteristic V-shaped internal capsule in horizontal section.

The genu contains predominantly corticonuclear (corticobulbar) fibres, which descend from motor regions of the cerebral cortex to the motor nuclei of cranial nerves in the brainstem. These fibres contribute to the voluntary control of muscles of the face, head and neck, including those involved in facial movement, mastication, swallowing and speech.

Superiorly, fibres of the genu continue into the corona radiata, while inferiorly they converge toward the cerebral peduncle before descending into the brainstem.

The genu is supplied mainly by lenticulostriate branches of the middle cerebral artery. Lesions involving the genu may interrupt corticonuclear fibres, producing contralateral weakness of cranial-nerve-innervated muscles, particularly affecting contralateral lower facial and bulbar movements.