A 65-year-old hypertensive man develops sudden slurring of speech. On protrusion, his tongue deviates to the left, and there is wasting and fasciculation of the left half of the tongue. The deviation occurs because:

• A The right styloglossus elevates and retracts the tongue to the opposite side
• B The left hyoglossus contracts and pulls the tongue toward the weak side
• C The intact right genioglossus protrudes the tongue and pushes it toward the paralyzed left side ✓
• D The right palatoglossus narrows the isthmus and displaces the tongue across the midline

Explanation

Genioglossus is the main protruder of the tongue. With a lower motor neuron lesion of the left hypoglossal nerve, the left genioglossus is paralyzed, so contraction of the intact right genioglossus thrusts the tongue forward and toward the weak left side. Wasting and fasciculation confirm a lower motor neuron lesion rather than an upper motor neuron one, in which the tongue deviates away from the hemiplegic side without wasting.

Reference: Snell's Clinical Neuroanatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.