#bone structure

• Apatite — The standard literary and most frequent form of the name of the natural phosphate mineral; it also represents a major structural component of hard tissues in human and animal organisms, found as hydroxyapatite as the core mineral within the structure of tooth enamel and bones.
• 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.