All muscles of tongue are supplied by hypoglossal nerve except ?
**Core Concept**
The hypoglossal nerve (CN XII) is a motor nerve responsible for the innervation of the extrinsic and intrinsic muscles of the tongue, playing a crucial role in its movements. The muscles of the tongue are divided into extrinsic and intrinsic muscles, with the extrinsic muscles controlling the tongue's position and the intrinsic muscles controlling its shape.
**Why the Correct Answer is Right**
The correct answer is not provided, but we can infer that the question is testing the student's knowledge of the specific muscles innervated by the hypoglossal nerve. The extrinsic muscles of the tongue, including the genioglossus, hyoglossus, and styloglossus, are indeed innervated by the hypoglossal nerve. However, the intrinsic muscles of the tongue, such as the palatoglossus, are actually innervated by the vagus nerve (CN X) via the pharyngeal plexus.
**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect, as the hypoglossal nerve innervates the genioglossus muscle.
* **Option B:** Incorrect, as the hypoglossal nerve innervates the hyoglossus muscle.
* **Option C:** Incorrect, as the hypoglossal nerve innervates the styloglossus muscle.
* **Option D:** Correct, as the palatoglossus muscle is actually innervated by the vagus nerve (CN X) via the pharyngeal plexus.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the palatoglossus muscle, which elevates the tongue and contributes to the formation of the palatoglossal arch, is the only intrinsic muscle of the tongue not innervated by the hypoglossal nerve. This knowledge is crucial for understanding the motor innervation of the tongue and its clinical implications.
**Correct Answer:** D. Palatoglossus