Corticobulbar Tract

tractus corticonuclearis

The corticobulbar (corticonuclear) tract carries motor fibres from the cortex to the motor nuclei of the cranial nerves in the brainstem. Most of these nuclei receive fibres from both hemispheres.

Anatomical Data

Structure & Connections

Location	From the face area of the motor cortex through the genu of the internal capsule and cerebral peduncle to the brainstem
Parts	Fibres to the trigeminal, facial, nucleus ambiguus, accessory and hypoglossal motor nuclei
Connections	Primary motor cortex Internal capsule Cranial nerve motor nuclei
Blood Supply	Middle cerebral artery (lenticulostriate branches); Anterior choroidal artery; Basilar artery perforators

Biomechanics

Function & Actions

Controls voluntary movements of the face, jaw, tongue, palate, throat and neck.

Clinical Relevance

Clinical Notes

Because the upper face receives fibres from both sides, a stroke causes weakness of only the lower face on the opposite side, unlike Bell palsy, which affects the whole face. Damage to both tracts causes pseudobulbar palsy with slurred speech, swallowing problems and emotional lability.

Pathology

Common Injuries & Conditions

Upper Motor Neuron Facial Palsy

Lower face weakness with forehead sparing after a stroke.

Pseudobulbar Palsy

Bilateral tract damage causing difficulty speaking and swallowing and uncontrolled crying or laughing.

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