In a subcondylar fracture of the mandible, in which direction is the condylar segment MOST commonly displaced?

Correct answer: B. Medially (and anteriorly)

• A. Lateral displacement occurs occasionally but is not the typical pattern, because no muscle pulls the condyle laterally.
• B. CORRECT. The LATERAL PTERYGOID muscle attaches to the pterygoid fovea on the anterior neck of the condyle and runs anteromedially to the lateral pterygoid plate. When the neck fractures, the unopposed pull of the lateral pterygoid draws the proximal (condylar) segment ANTERIORLY and MEDIALLY. This is why medial override is the classic radiographic finding.
• C. Posterior displacement is not produced by the lateral pterygoid vector.
• D. Superior displacement into the fossa would require the condyle to be driven upward, which is a different injury pattern (intracapsular crush).

Note: One muscle explains this whole question: lateral pterygoid = anteromedial pull on the condyle.