A 65-year-old develops sudden right hemiplegia with right facial weakness of the upper motor neuron type, along with deviation of the tongue to the right on protrusion. Which structure is most likely injured?

• A Right internal capsule
• B Left medullary pyramid
• C Left internal capsule (posterior limb and genu) ✓
• D Right corticobulbar fibers in the pons

Explanation

The left internal capsule carries corticospinal fibers (posterior limb) to the right body and corticobulbar fibers (genu) to the right facial nucleus (lower face) and bilateral upper facial nucleus; the hypoglossal nucleus receives crossed corticobulbar supply, so a left capsular lesion produces right-sided UMN facial weakness and right tongue deviation (ipsilateral to the lower motor neuron effect of the hypoglossal). Right-sided lesions would produce left-sided deficits. Medullary pyramid lesions spare the facial nucleus.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.