Skeletal unit construction of rat mandible based on the masticatory muscle anatomy and double microcomputed tomography.

This study aimed to divide the mandible into skeletal units based on three-dimensional (3D) muscular anatomy with microcomputed tomography (micro-CT) of Sprague-Dawley rat. Five normal rats were micro-CT scanned at 12 weeks of age before and after contrast enhancements for the masticatory muscles. Three-dimensional reconstruction of the mandible was performed from the initial micro-CT images, followed by segmentation of the masticatory muscles using the second enhanced micro-CT data. Bone and muscle models were superimposed based on the teeth and bony structures to evaluate muscular orientation and attachment. The mandible was divided into skeletal units using the bony structures and muscle attachments. The mandibular foramen and mental foramen were adopted as the reference points based on their anatomical and developmental significance. The skeletal units consisted of the condylar, coronoid, angular, body and symphyseal units. Further evaluation of these units in relation to development, growth, and other biology and medicine will be helpful in elucidating their biological identities.