What is Not a muscle of the tongue and explain in detail?
Intrinsic muscles of the tongue: 

Muscles found entirely within the tongue
Longitudinal, transverse, and vertical muscles
Function - change the shape of the tongue.

Extrinsic muscles of the tongue:

Genioglossus, Styloglossus, and hyoglossus, Palatoglosus.
All insert into the tongue, originate from surrounding structures