## **Core Concept**
The hypoglossal nerve, also known as the 12th cranial nerve, primarily provides motor innervation to the muscles of the tongue. It supplies all the intrinsic and extrinsic muscles of the tongue except for one.

## **Why the Correct Answer is Right**
The hypoglossal nerve supplies the following muscles:
- Intrinsic muscles (superior longitudinal, inferior longitudinal, transverse, and vertical muscles)
- Extrinsic muscles (genioglossus, hyoglossus, and styloglossus)

The palatoglossus muscle, which is involved in elevating the posterior part of the tongue and is part of the palatal musculature, is not supplied by the hypoglossal nerve. Instead, it is supplied by the vagus nerve (cranial nerve X) through the pharyngeal plexus.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Genioglossus is supplied by the hypoglossal nerve. It is the principal muscle responsible for protruding the tongue.
- **Option B:** Styloglossus is also supplied by the hypoglossal nerve. It helps in retracting and elevating the tongue.
- **Option C:** Hyoglossus is supplied by the hypoglossal nerve as well. It depresses and retracts the tongue.

## **Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that the hypoglossal nerve's function can be tested by asking a patient to stick their tongue out. If the tongue deviates to one side, it indicates weakness on that side, suggesting a lesion of the hypoglossal nerve on the opposite side of the deviation.

## **Correct Answer:** . Palatoglossus