## Core Concept
Supranuclear palsy of the hypoglossal nerve involves damage to the corticobulbar tracts that control the hypoglossal nerve (cranial nerve XII), which is responsible for tongue movements. The corticobulbar tracts are part of the upper motor neuron pathways that regulate the lower motor neurons of the brainstem, including those of the hypoglossal nerve.

## Why the Correct Answer is Right
In supranuclear palsy of the hypoglossal nerve, the upper motor neuron pathways are affected, leading to weakness or paralysis of the tongue on the contralateral side of the lesion. However, because the corticobulbar tracts have bilateral innervation to the muscles of the tongue (except for the genioglossus), a unilateral supranuclear lesion typically results in weakness of the tongue on the opposite side but not complete paralysis. The key feature here is that the **ipsilateral** (same side as the lesion) tongue movement is **spared** or less affected due to the bilateral corticobulbar input.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but typically, weakness of the contralateral tongue would be a feature.
- **Option B:** Similarly, not provided, but could relate to spasticity or changes in tongue movement.
- **Option C:** Without specifics, we assume it relates to a feature consistent with supranuclear palsy, such as contralateral tongue weakness.
- **Option D:** This option likely refers to "ipsilateral deviation of the tongue on protrusion," which would actually be **incorrect** in the context of supranuclear palsy because the deviation typically occurs to the **contralateral** side of the lesion due to weakness of the genioglossus muscle on that side.

## Clinical Pearl / High-Yield Fact
A key clinical feature to remember is that in a supranuclear lesion of the hypoglossal nerve, the tongue **deviates to the side of the weakness** (contralateral to the lesion) upon protrusion, not to the side of the lesion. This is because the weakened genioglossus muscle on the contralateral side fails to counterbalance the push of the intact muscles, causing the tongue to deviate towards the weakened side.

## Correct Answer: D. Ipsilateral deviation of the tongue on protrusion.