Clinical implications of anomalous muscle insertion relative to jaw movement and mandibular dysfunction: the anterior belly of the digastric muscle in a cadaver.

This case report of an anomalous insertion of the anterior belly of the digastric muscle in a cadaver considers the components involved in mandibular movement as well as the radiologic changes that could be expected in asymmetric function of the temporomandibular joints. The occlusal scheme of the cadaver was noted and, after transcranial radiographs were taken, both joints were anatomically dissected. While the left condyle-disc relationship appeared normal and properly approximated, the right joint (which was assumed to be translating in an anterior, inferior, and medial direction on each opening, ie, left lateral deviation) was found to have a complete articular disc perforation with severe bony erosion and condylar spicule formation. These findings may shed some light on dyskinesia diagnosis and treatment outcome; ie (1) what degree occlusally related etiologies may be affixed to individuals with aberrant mandibular movement, (2) why many diagnosed cases of mandibular dysfunction continue following irreversible dental restorative treatment via augmentation of the existing "malocclusion," and (3) what may be the clinical implications of or limitations inherent in the use of jaw-tracking devices in the diagnosis and interpretation of dyskinetic movement in the presence of aberrant muscle attachments.