Bony tubercle at external occipital protuberance and prominent ridges.

During the examination of skulls in the osteology laboratory of the Department of Anatomy, CSM Medical University, Lucknow, UP, India, a skull was detected having exostosis projecting from the external occipital protuberance along with prominent superior nuchal lines appearing as ridges. Measurements of the tubercle were taken by vernier calipers, and possible causes and clinical implications were analyzed.The length of this tubercle was 8 mm; width was 6 mm and thickness 1.5 mm. The superior nuchal lines appeared as prominent ridges. The height of the ridges was 5 mm on both sides; the thickness was 10 mm and 8 mm, respectively, on both the right and left sides. The length of the ridges was 4.8 cm on the right side and 4.4 cm on the left side.The tubercle may cause occipital headache in general but especially in tree climbers and basketball/volleyball players during vertical biomechanical movements of the neck. The knowledge of this tubercle is of paramount importance to anatomists, neurosurgeons, sports physicians, radiologists, forensic experts, and anthropologists.