Safety muscle of the tongue is –
**Core Concept**
The safety muscle of the tongue, also known as the extrinsic tongue muscle, plays a crucial role in protecting the airway by preventing the tongue from falling back and obstructing the pharynx during sleep. This muscle is essential for maintaining the patency of the airway, especially in individuals with certain neurological or muscular disorders.
**Why the Correct Answer is Right**
The safety muscle of the tongue is the genioglossus muscle, which is one of the extrinsic tongue muscles. It originates from the mandible and inserts into the posterior aspect of the body of the tongue. When the genioglossus muscle contracts, it protrudes the tongue and prevents it from falling back and obstructing the airway. This muscle is innervated by the hypoglossal nerve (CN XII), which is responsible for controlling the movements of the tongue.
**Why Each Wrong Option is Incorrect**
* **Option A:** The hyoglossus muscle is another extrinsic tongue muscle, but it is not the safety muscle of the tongue. It depresses and retracts the tongue.
* **Option B:** The styloglossus muscle is an extrinsic tongue muscle that elevates and retracts the tongue, but it is not the safety muscle.
* **Option C:** The palatoglossus muscle is an intrinsic tongue muscle that elevates the posterior part of the tongue and is not the safety muscle of the tongue.
**Clinical Pearl / High-Yield Fact**
The genioglossus muscle is essential for maintaining airway patency, and its dysfunction can lead to obstructive sleep apnea and other respiratory complications. Patients with neurological disorders, such as Parkinson's disease, may experience genioglossus muscle weakness, which can increase the risk of airway obstruction.
**Correct Answer:** D. Genioglossus muscle.