Third Occipital Condyle - Advanced Radiology …advancedradteaching.com/teachingfiles/405.pdfThe...
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Third Occipital Condyle Joseph Junewick, MD FACR 09/16/2010 History 5 year old female with sinus congestion. Diagnosis Third Occipital Condyle 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. Findings CT-Sagittal and coronal images reveal an ossicle in the anterior midline interposed between the clivus and dens. Reference Prescher A, , Brors D, Adam G. Anatomic and Radiologic Appearance of Several Variants of the Craniocervical Junction. Skull Base Surgery (1996); 6:83-94.
Transcript of Third Occipital Condyle - Advanced Radiology …advancedradteaching.com/teachingfiles/405.pdfThe...
Third Occipital CondyleJoseph Junewick, MD FACR
09/16/2010
History5 year old female with sinus congestion.
DiagnosisThird Occipital Condyle
DiscussionThe 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 alwayspresent in reptiles; in humans it is found in approximately 0.5% of the population and may exist as adiscrete condyle or an isolated osseous element. It may serve as an articulation with the tip of thedens or with the anterior atlantic arch. The third occipital condyle is a vestige of proatlas (a derivativeof the 4th occipital and 1st cervical sclerotome). The variations of the anatomic appearances of thethird condyle can be explained by the different degrees of persistence. An isolated, articulatedcondylus tertius, located in the median-sagittal plane and the anterior margin of the foramenoccipitale magnum represents the highest degree of persistence.
FindingsCT-Sagittal and coronal images reveal an ossicle in the anterior midline interposed between the clivusand dens.
ReferencePrescher A, , Brors D, Adam G. Anatomic and Radiologic Appearance of Several Variants of theCraniocervical Junction. Skull Base Surgery (1996); 6:83-94.
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