Migration of craniofacial periosteum in guinea-pigs with unilateral masticatory muscle paralysis.

The amount and direction of movement of the fibrous periosteum of the nasal, frontal, and parietal bones in the guinea-pig have been documented after experimentally induced unilateral paralysis of the masticatory muscles. Marked craniofacial asymmetries and muscle atrophy were observed after electrolytic lesions of the trigeminal motor nucleus were made. The induced muscle paralysis had only a small effect on the periosteal migration. The direction of migration was slightly less medial on the operated as compared to the non-operated side. The periosteal migration of the non-operated side closely paralleled the direction of movements observed in the control animals studied previously. There was an increase of bone apposition at the coronal sutural margins on the operated side and an associated convexity of the midline toward the operated side. Additional research on the dynamic relationship of the muscle-periosteum-bone interface is necessary in order to understand better the morphogenetic controls of craniofacial growth.