The proposed study will correlate perioral innervation, perioral muscle activity, and forces generated by perioral muscles in pigs. Perioral muscles of the lips comprise a type of muscular hydrostat. Their unique architecture allows highly coordinated movements. These intricate movements depend upon the pattern of innervation by cranial nerve VII. To understand the basis of perioral muscle contraction, we will perform nerve stimulations in order to assign functions and map motor unit territories. In vivo coordinated activity patterns of perioral muscles are unknown in laboratory animals, and little studied even in humans. Perioral muscles are often presumed to have a higher activity frequency and greater duration of contraction than masticatory muscles, which in turn is thought to influence bone growth. Therefore, we plan to investigate the activity patterns of perioral musculature. The forces generated by perioral muscle contraction are germane to the putative role of these muscles as contributing factors in malocclusions. It is possible that they exert pressure normal to the underlying bone surface. We will investigate bone strain and pressure generated by perioral musculature. The extent to which forces from these muscle influence craniofacial development is virtually unexplored and is the study's ultimate goal.
| Marshall, Christopher D; Hsu, Ron H; Herring, Susan W (2005) Somatotopic organization of perioral musculature innervation within the pig facial motor nucleus. Brain Behav Evol 66:22-34 |
| Herring, S W; Rafferty, K L; Liu, Z J et al. (2001) Jaw muscles and the skull in mammals: the biomechanics of mastication. Comp Biochem Physiol A Mol Integr Physiol 131:207-19 |
