Damage to which nerve causes the tongue to deviate toward the same side?

Damage to which nerve causes the tongue to deviate toward the same side?

• A. CN XII
• B. CN IX
• C. CN X
• D. CN VII

Answer: (A)

When a nerve that moves the tongue is damaged on one side, the protruding movement becomes weaker on that side. The tongue is shaped and propelled forward mainly by the genioglossus muscle, which is innervated by the hypoglossal nerve. If the hypoglossal nerve is lesioned on one side, the genioglossus on the opposite, intact side still pushes the tongue outward, so the tongue deviates toward the weakened (injured) side when you try to protrude it. The other nerves listed don’t control the intrinsic and most extrinsic tongue muscles responsible for this protrusion, so their damage would cause other symptoms (swallowing, sensation, facial movement) but not this specific tongue deviation.

When a nerve that moves the tongue is damaged on one side, the protruding movement becomes weaker on that side. The tongue is shaped and propelled forward mainly by the genioglossus muscle, which is innervated by the hypoglossal nerve. If the hypoglossal nerve is lesioned on one side, the genioglossus on the opposite, intact side still pushes the tongue outward, so the tongue deviates toward the weakened (injured) side when you try to protrude it. The other nerves listed don’t control the intrinsic and most extrinsic tongue muscles responsible for this protrusion, so their damage would cause other symptoms (swallowing, sensation, facial movement) but not this specific tongue deviation.