Removal of the temporalis muscle from its origin: effects on the size and shape of the coronoid process.

Removal of certain masticatory muscles from their mandibular attachment has produced a decrease in the size of the regions of insertion, particularly of the coronoid process and mandibular angle.1-5 In these studies, the temporalis, medial pterygoid, and masseter muscles were removed from their mandibular attachment or were almost totally extirpated. It has been concluded that the maintenance of the form of the bony processes to which these muscles attach is the result of muscle tension. Also, it has been shown that the arteries supplying the coronoid process, angle, and condyle of the rat, guinea pig, monkey, and man arise from vessels that supply the muscles attaching to these processes, and generally not from the inferior alveolar artery which primarily supplies the mandibular body and teeth.6-9 Therefore, it would seem that removal of the masticatory muscles from their mandibular attachment would eliminate the arterial supply to these bony processes. If, however, the blood supply of the mandible is maintained while direct muscle tension is decreased or eliminated by separating the masticatory muscles from their cranial attachment, the effect of the lack of muscle tension could be evaluated. It is the purpose of this study to note the effects on the coronoid process produced by removal of the temporalis muscle from its cranial origin.