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Parasymphyseal Fracture Displacement — ORE Part 1 MCQ

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HardOral SurgeryParasymphyseal Fracture DisplacementORE Part 1

A patient has a displaced unilateral parasymphyseal fracture of the mandible. Which muscle group is principally responsible for inferior displacement of the anterior (mesial) fracture segment?

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Correct answer: E — Mylohyoid, geniohyoid and anterior belly of digastric

**A is correct.** The anterior (mesial) segment in a displaced parasymphyseal fracture is pulled inferiorly by the suprahyoid muscles: mylohyoid, geniohyoid and the anterior belly of digastric. Their mandibular attachments are retained by the anterior segment, producing the characteristic downward displacement. The masseter, medial pterygoid and temporalis principally elevate the posterior/distal segment, so option B describes the opposing muscle group rather than the cause of anterior-segment displacement. The lateral pterygoid acts primarily on the condylar neck/head complex and is relevant to condylar fracture displacement, not this pattern. Buccinator has no meaningful primary role in bony fracture-segment displacement.

Reference: Nardi C, et al. Imaging of mandibular fractures: a pictorial review. Insights into Imaging, 2020. Figure 4 describes mylohyoid, geniohyoid and anterior digastric pulling the mesial mandibular fragment downward. https://pubmed.ncbi.nlm.nih.gov/32076873/