#epistropheus
- Axis vertebra — The second cervical vertebra of the spine in humans and higher animals, situated directly below the atlas, serving the structural role of a pivot for the delicate rotation of the head. The bony piece is characterized by a vertical process called the odontoid process, around which cranial torsional movements are executed. In zoology, the term also designates a species of deer native to India (Cervus axis), characterized by a spotted coat and slender antlers.