Palatoglossus muscle
The palatoglossal muscle is a muscle of the soft palate and an extrinsic muscle of the tongue. Its surface is covered by oral mucosa and forms the visible palatoglossal arch. Structure
From its origin, it passes anteroinferiorly and laterally. It passes anterior to the palatine tonsil. Origin 
The palatoglossus arises (the oral aspect of) the palatine aponeurosis of the soft palate, where it is continuous with its contralateral partner (i.e. the same muscle of the opposite side). Insertion 
It inserts onto the side of the tongue; some of its fibers extend over the dorsum of the tongue, and some pass into the substance of the tongue to intermingle with the transverse muscle of tongue. Innervation
The palatoglossus muscle receives motor innervation from the pharyngeal plexus of vagus nerve. It is the only muscle of the tongue not innervated by the hypoglossal nerve (CN XII). Controversy 
Some sources state that the palatoglossus is innervated by fibers from the cranial part of the accessory nerve (CN XI) that travel via the pharyngeal plexus. Other sources state that the palatoglossus is not innervated by XI hitchhiking on X, but rather it is innervated by IX via the pharyngeal plexus formed from IX and X.

Actions/movements 
The palatoglossus elevates the root of the tongue (i.e. the posterior attached portion of the tongue). It approximates the ipsilateral (same side) palatoglossal arch to the contralateral (opposite side) one, thus separating the oral cavity and the oropharynx. Function
It closes the oropharyngeal isthmus, and aids initiation of swallowing. This muscle also prevents the spill of saliva from vestibule into the oropharynx by maintaining the palatoglossal arch. References

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Muscles of the head and neck
Tongue
Innervation of the tongue.