Mandibular Symphysis

The mandibular symphysis is the anterior midline of the mandible. A symphyseal fracture is defined as a sagittally oriented fracture extending inferiorly from the central incisors. A symphyseal fracture can be a primary fracture as a result of an anterior midline blow, or a secondary fracture in accordance with the "ring bone rule."

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Images show a mandibular symphysis fracture with significant displacement. Medially dislocated fractures of both manidubular condyles are seen. The left mandibular condyle fracture extends through the left mandibular head. Both temporomandibular joint fossae are empty. A LeFort II fracture on the right and a LeFort III fracture on the left are seen with bilateral displaced fractures of the lateral pterygoid plates. The frontal processes of the maxilla are mildly displaced. Fractures can be appreciated passing superomedially through the anterior walls of the maxillary sinsues, adjacent to the inferior orbital foramina, through the nasolacrimal ducts, to the nasal bridge. All of the walls of both maxillary sinuses are disrupted. A severe tripod fracture is seen on the left with fragmentation of the left zygomatic arch. There is fracture of the left orbital floor without herniation of orbital contents. Displaced nasal bone and nasal septum fractures can be appreciated. Hemorrhagic opacification of the ethmoid and maxillary sinuses and orbital emphysema on the left are seen.

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Axial image demonstrates a displaced mandibular symphysis fracture.

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A more cephalad axial image agian demonstrates the displaced mandibular symphysis fracture.

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A more cephalad axial image agian demonstrates the displaced mandibular symphysis fracture.

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Sagittal image demonstrates medial displacement of the mandibular condyles secondary to bilateral mandibular condyle fractures. A fracture of the right lateral pterygoid plate can be appreciated.