The muscles involved in swallowing or deglutition are four muscles located at the base of the tongue and in the mandible. Two of them are attached to the hyoid bone in the upper neck and are not parts of the tongue; the other two are anchored to the mandible (chin), being parts of the root of the tongue.
The muscles that takes part in deglutition are: 1) the mylohyoid, which is a paired triangular muscle that runs down obliquely from the mandible to the hyoid bone, elevating the tongue and this bone in the first phase of swallowing; 2) the genioglossus, which is anchored to the spine of the mandible and then fans out to form the base of the tongue as it runs backward and upward; 3) the geniohyoid, which is a paired muscle that lies underneath the genioglossus, being a thin muscle attached to the mandible and the hyoid bone (like the mylohyoid, this muscle is not part of the tongue but intervenes in deglutition); and 4) the hyoglossus muscle, which is attached to the hyoid bone and runs up to the sides of the tongue. Although the epiglotis participates in the swallowing or deglutition process, it is not a muscle, for it is an elastic cartilaginous structure situated at the root of the tongue.
Process of Swallowing (video)