Fig. 1 The apex of the combined muscular control of the mandible in all functioning movements is located at the dens between the atlas and axis cervical vertebrae.
Fig. 2 When the mouth opens the 136 muscles above and below the mandible pivot the jaw at the xy-axis. The condyle translates forward and downward as the mouth opens.
Fig. 3 When the mandibular teeth occlude above the x-x plane, a pathologic Curve of Spee exists and the head of the condyle moves superiorly and distally.
Fig. 4 If the mandible did actually pivot in the TMJ as has been accepted as fact, the mandibular positioning as herein depicted would be able to occur.
A question for Bruxistas: This horizontal line, does it seem right? These are drawings that were used to diagnose “The Dental Distress Syndrome” (Dr. A.C. Fonder). (1988) Yet another name for us bruxistas. See the following post, Lateral Ricketts. Compare the inclination of the occlusal plane in the photograph and the following X-Ray. Doesn’t that seem “more” natural?
Tags: how a jaw opens, TMJ drawings