The posterior condylar canal.

PURPOSE To assess the prevalence and appearance of the posterior condylar canal using high-resolution CT. METHODS One hundred twenty-three high-resolution temporal bone CT examinations were retrospectively reviewed for the presence or absence of the posterior condylar canal. Thirty-four gross skulls were also examined. RESULTS The posterior condylar canal was identified on CT bilaterally in 31% of the final study group and unilaterally in 50%. On gross specimens, this structure was identified in 55.9% bilaterally and 17.6% unilaterally. The posterior condylar canal, when present, is readily identifiable in a predictable location. The imaging appearance of this structure is dependent on its relationship to the angle of scanning. CONCLUSION The posterior condylar canal is among the largest emissary foramina in the human skull. Recognition of this structure and its role as an alternative source of venous drainage from the brain will help avoid misinterpretation during CT examination.