Antagonism of temporal fascia to masseteric contraction

This study was undertaken to test the hypothesis that the temporal fascia lends significant aid to the zygomatic arch in resisting the tensions of the m. masseter. It consisted of the unilateral removal of the fascia in two adult Cebus monkeys from its attachment on the superior and lateral surfaces of the arch, which were then covered with a plate of 24K 50 gauge gold to prevent re‐attachment. Frontal and lateral cephalometric x‐rays were taken and the animals were given three i.v. injections of lead acetate (4 mg/kg body weight) at two‐week intervals beginning at time of operation and sacrificed two weeks after the last. The arches were removed close to their attachments and prepared for histological study according to modified technique of Scheiman‐Tagger and Brodie ('64). Frontal sections through the right and left arches revealed striking differences between them. The operated side measured approximately 25% less mediolaterally and 16% greater superoinferiorly than the unoperated side. Oriented frontal and basal head x‐rays at 5 ft target distance revealed the operated side to be 4 mm lower and 2 mm closer to the midline. The lead lines showed the extensive internal as well as external remodeling that had taken place. Deposition and resorption areas indicated the drifting of marrow spaces and of the zygomaticotemporal suture in the direction of the unopposed pull of the m. masseter.