Atlas Bone Anatomy
Axis Bone Anatomy
Introduction to Axis Bone Anatomy:
One of the most prominent features of the axis bone is a superior, tooth-like projection called the odontoid process (or dens).
The odontoid process articulates with the anterior arch of the atlas bone, where they form a pivot joint.
When the head rotates side-to-side, the atlas bone rotates around the peg-like odontoid process. This is the reason why the second cervical vertebra is also called the axis bone.
Markings of the Axis Bone:
- Body or centrum (Corpus vertebrae) is a cylindrical mass on anterior side of the vertebra. It articulates with body of the vertebra below (C3).
- Odontoid process or dens (Dens axis) is a prominent rounded superior projection from the body.
This tooth-like elevation serves a stable point around which the atlas bone rotates (Gr., odous, tooth).
- Superior articular facet (Facies articularis superior) is a smooth, sightly convex surface that articulates with the inferior articular facet on the altas bone above (C1).
[Superior view/ Lateral view]
- Transverse process (Processus transversus) is a small extension that lies inferior to the superior articular facet and projects laterally. It is an attachment site for muscles that move the head and neck.
- Transverse foramen (Foramen transversarium) is a hole in the transverse process that serves as a passageway for the vertebral artery and vein.
- Vertebral foramen (Foramen vertebrale) is a large opening in the center of the axis bone that forms a passageway for the spinal cord.
Learn more about vertebrae anatomy with these spine anatomy diagrams and quizzes.
- Vertebral arch or neural arch (Arcus vertebrae) is the bony archway that encloses the posterior vertebral foramen and protects the spinal cord from damage.
- Lamina of the vertebral arch (Lamina archus vertebrae) is one of two plates that forms the dorsal portion of the vertebral arch.
- Spinous process (Processus spinosus) is a narrow posterior projection from the junction of the two laminae. It is an attachment point for ligaments and muscles that move the head and neck.
- Inferior articular process (Processus articularis inferior) is a downward projection from the vertebral arch. Its flattened inferior surface or facet makes contact with the superior articular facet on C3.
Superior view: [Show/Hide answers]
Lateral view: [Show/Hide answers]
Interactive quiz about the axis
Quiz – Axis Bone Anatomy