Anatomy study note · Back
Axis (C2)
The second cervical vertebra, identified by the peg-like odontoid process (dens) projecting upward from its body. The dens is the body of the atlas, fused to the axis during development.
Key points
- Dens (odontoid process) = body of the atlas fused to C2.
- Ligaments: apical, alar ×2, cruciate (transverse part), membrana tectoria.
- Odontoid fracture: falls or blows on the head.
- Hangman’s fracture: pedicles of C2, hyperextension; cord often spared.
- Odontoid may remain separate.
- Vertebra = caudal half of one sclerotome + cranial half of the next.
- Bone: type I collagen + hydroxyapatite.
- Osteoblast builds, osteocyte maintains, osteoclast resorbs.
The full note in the atlas also covers
Features · Articulations · Histology · Development · Clinical notes
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Written from
- Snell’s Clinical Anatomy by Regions, 10th ed., ch. 2, PDF pp. 128–129, 145, 154
- Inderbir Singh’s Human Embryology, ch. 10, PDF pp. 134–137, 138
- BRS Cell Biology & Histology, 7th ed., ch. 7, PDF pp. 121–125, 130
More from the back
- Cervical vertebrae
- Deep muscles of the back
- Intervertebral discs
- Ligaments of the vertebral column
- Lumbar vertebrae
- Spinal cord
- Spinal nerves
- Suboccipital muscles
- Thoracic vertebrae
- Thoracolumbar fascia
- Vertebral column
- Atlas (C1)
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