The Presence of an Anterior Tubercle in the Foramen Magnum of the Cranium: A Case Report With Potential Clinical Consequences.

There are not so many variants regarding the foramen magnum (FM). However, the existence of a prominent eminence at the anterior border of FM is one of the variations. In the current study, we detected such a tubercle in a dried skull of an old man's skeleton, with its base arising from the midpoint of the internal aspect of the anterior margin of the FM. The apex of this tubercle was oriented backwards. As for the dimensions, the anteroposterior distance was measured at 4 mm, and the transverse distance at 5 mm. That tubercle is usually circular or ovoid in shape, and its appearance is commonly overlooked by radiologists and physicians. That eminence can potentially damage the pyramidal fibers of the spinal cord in extreme flexion of the head, usually during a cranial trauma. Both radiologists and clinicians should be aware of this rare variant, as it may be an incidental radiographic finding or a reason for damage to the spinal cord during head and neck injuries. Moreover, there is a positive cost-effectiveness for the patient and the public health system of their country, since the costs for both will be eliminated if the patient takes their precautions.