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Nasal Dermoid
Joseph Junewick, MD FACR
over 9 years ago
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Case History

5 year old female with sinus congestion.

Case Detail

Anatomy: Brain-Spine
Joseph Junewick, MD FACR
Diagnostic Category: Normal variant
Created: over 8 years ago
Updated: over 8 years ago
Modality/Study Types: CT
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Case Images

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Reveal Findings

CT – Sagittal and coronal images reveal an ossicle in the anterior midline interposed between the clivus and dens.

Reveal Discussion

The third occipital condyle (condylus tertius or median occipital condyle) was first described by J.F. Meckel in 1815, as a bony process in the anterior midline of the foramen magnum. It is always present in reptiles; in humans it is found in approximately 0.5% of the population and may exist as a discrete condyle or an isolated osseous element. It may serve as an articulation with the tip of the dens or with the anterior atlantic arch. The third occipital condyle is a vestige of proatlas (a derivative of the 4th occipital and 1st cervical sclerotome). The variations of the anatomic appearances of the third condyle can be explained by the different degrees of persistence. An isolated, articulated condylus tertius, located in the median-sagittal plane and the anterior margin of the foramen occipitale magnum represents the highest degree of persistence.

Reveal Diagnosis

Third Occipital Condyle

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