Adult monkey coronoid process after resection of trigeminal nerve motor root

A smaller or absent coronoid process has been reported, by some investigators but not by others, in growing animals following resection of the temporalis muscle. The trauma of resection, altered function, hemorrhage, scar tissue, and changes in vascularity may have influenced the results. The purpose of this experiment was to observe in adult Macaca mulatta the fully grown coronoid process after decreasing or eliminating neurofunctional activity of the temporalis muscle unilaterally without the trauma of local resection. In two males and three females the motor root of the trigeminal nerve which innervates the temporalis muscle was resected intracranially. In three control animals of both sexes the same surgical procedure was performed except for resection of the nerve. At postmortem, one year later, the temporalis muscle mass was atrophic on the resected side. There were no significant morphological differences, however, between the right and left sides of the mandible, including the coronoid process, regardless of which motor root of the fifth nerve had been resected, which side had been sham-operated, or sex. An extensive deposit of calculus on the buccal surfaces of the teeth on the operated nerve side was a consistent, conspicuous finding.