A 40-year-old female librarian is brought to the emergency depament. Neurologic examination reveals the following: blood pressure 160/90 mm Hg, weakness on the right side of her inferior face, no weakness in upper or lower limbs, tongue deting to right side on protrusion, and uvula deting to the left side when patient says "ah." In which of the following loci is the lesion causing these symptoms found?
A lesion of the genu of the internal capsule destroys coicobulbar fibers. The facial nucleus receives bilateral coicobulbar input, the upper face division receives bilateral input, and the lower face division receives only contralateral input. (so lesion of left genu will present as Right side lower face weakness) The hypoglossal nucleus receives only contralateral coicobulbar input. So lesion of left genu will present as right side hypoglossal paralysis. Hence, when the tongue is protruded, it detes to the right (side of LMN lesion) owing to the unopposed activity of the intact genioglossus. Lesion of Left genu will cause paralysis of opposite (Right) vago-accessory complex. So the uvula detes to Left (intact side / opposite site of LMN lesion) when the patient says "ah.
Anterior limb of internal capsule
Claustrum
Genu of internal capsule, left side
Paracentral lobule, right side
Neuroanatomy, Head and Neck