The palatoglossus, glossopalatinus, or palatoglossal muscle is a small fleshy fasciculus, narrower in the middle than at either end, forming, with the mucous membrane covering its surface, the glossopalatine arch.

It arises from the anterior surface of the soft palate

Soft palate

The soft palate is the soft tissue constituting the back of the roof of the mouth. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone....

, where it is continuous with the muscle of the opposite side, and passing downward, forward, and lateralward in front of the palatine tonsil, is inserted into the side of the tongue

Tongue

The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...

, some of its fibers spreading over the dorsum, and others passing deeply into the substance of the organ to intermingle with the Transversus linguæ.

Action

Elevates posterior tongue, closes the oropharyngeal isthmus, and aids initiation of swallowing.

Innervation

The palatoglossus is the only muscle of the tongue that is not innervated by the hypoglossal nerve

Hypoglossal nerve

The hypoglossal nerve is the twelfth cranial nerve , leading to the tongue. The nerve arises from the hypoglossal nucleus and emerges from the medulla oblongata in the preolivary sulcus separating the olive and the pyramid. It then passes through the hypoglossal canal...

 (CN XII). It is innervated by the Vagus nerve

Vagus nerve

The vagus nerve , also called pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves...

 (CN X)

But some sources state that the palatoglossus is innervated by fibres from the cranial part of the accessory nerve

Accessory nerve

In anatomy, the accessory nerve is a nerve that controls specific muscles of the shoulder and neck. As part of it was formerly believed to originate in the brain, it is considered a cranial nerve...

 (CN XI) that travel via the pharyngeal plexus

Pharyngeal plexus of vagus nerve

The pharyngeal plexus is a network of nerve fibers innervating most of the palate, larynx, and pharynx.It is located on the surface of the middle pharyngeal constrictor muscle.-Sources:...

.

Other sources state that the palatoglossus is not innervated by XI hitchhiking on X, but rather it is innervated by X via the pharyngeal plexus formed from IX and X.