ring-shaped C1 Atlas Vertebra

Credit: http://www.bartleby.com/107/illus84.html
article: Yoga Anatomy: Cervical Spine 		Other images from this article
ring-shaped C1 Atlas Vertebra C3 - C6 General Cervical Vertebra Seventh Cervical Vertebrae
ring-shaped C1 Atlas Vertebra, http://www.bartleby.com/107/illus84.html