Neuromuscular System and Jaw Deformities

抄録

The development of jaw deformities in the human provides some of the most challenging issues of cause and effect relationships between muscle and bone. Genetic factors provide the underlying control for the development of the craniomandibular region, but the neuromuscular system is intimately woven with the bone. While genetic factors effect the muscle and bone, these two tissues can also interact to effect eachother. The best experimental data supporting this concept is presented. Asymmetrical mandibles can be developed in the experimental animal models when bilateral jaw muscles become unequal in the force across the craniomandibular skeleton (e. g., lesioning many trigeminal motoneurons unilaterally). Mutations that prevent fetal jaw muscle development or impairing muscle contraction in the fetal stage alter the shape and size of the cranioskeleton including the mandible. Clinically, systemic muscular diseases that include the jaw muscles (e. g., masseter, temporalis) lead to significant increases in vertical facial development and the development of a severe retrognathic. Jaw muscles must develop sufficient periodic forces on the craniomandibular skeleton, particularly the dentoalveolar and condylar regions, to control growth of the mandible. The neuromuscular system effects a third property of the craniomandibular bone, the mineralization of the tissue. The pattern of cortical bone mineralization may prove to be one of the effective methods to assess the actual forces developed in the craniomandi-bular skeleton by the jaw muscles.