The geniohyoid arises from the inferior mental spine of the mandible and passes backward and downward to insert on the body of the hyoid bone.
It has two functions depending on which bone is fixed:
Fixation of the mandible elevates and pulls the hyoid bone forward.
Fixation of the hyoid bone pulls the mandible downward and inward.
The geniohyoid is innervated by a branch from the anterior ramus of C1 carried along the hypoglossal nerve [XII].