fibrous capsules of the lateral and medial joints are thin and provide only minimal support, therefore ligamentous attachments. The primary ossification centers first appear at the cervicothoracic junction at 9 weeks in utero and are followed by upper cervical then thoracolumbar vertebrae with the primary ossification centers of the lumbar neural arches the last to appear at approximately 14 weeks in utero 3. median atlanto-axial (atlanto-dental or atlanto-odontoid) joint: pivot-type synovial joint with anterior and posterior articulations of odontoid process/dens of C2 and anterior arch and transverse ligament of C1. (The axis is the 2nd highest spinal bone.) The atlas is the first bone of your neck it sits on top of the axis. Normal develop-ment of the spine is reviewed, including synchondroses and ossification centers. The odontoid process, also known as the dens, is an upward projectile of bone that arises from the front part of the center of the axis vertebra. Since the original odontoid fracture classifications by Anderson and D’Alonzo in 1974, several authors have suggested an additional comminuted subtype of Type II fracture, designated as IIA. This article reviews some of the more common imaging findings that may present as pseudotrauma. as for typical vertebrae but has two extra primary ossification centers for the dens (odontoid process) Anatomic variants and incomplete ossification and fusion of the develop-ing spine may result in an erroneous diagnosis of injury or disease. C2 (axis): five primary ossification centers in total.one for each side of the posterior arch (two in total) Os odontoideum (plural: ossa odontoidea) is an anatomic variant of the odontoid process of C2 and needs to be differentiated from persistent ossiculum terminale and from a type 2 odontoid fracture.It can be associated with atlantoaxial instability.C1 (atlas): three primary ossification centers in total.The alar ligaments limit rotation of the head, specially in lateral flexion. They pass from here on the odontoid process, to here on the inside of the occipital condyles. There are some differences for C1 and C2 1-3: We’ll remove all of the cruciform ligament to see the odontoid process and the alar ligaments. one for each half of the neural arch (two in total).one in the centrum (for most of the vertebral body).The C3-L5 vertebrae typically have three primary ossification centers that start appearing at 9 weeks in utero and finish primary ossification by one year 1-4: 12, in whom there had been a craniovertebral fusion ten years previously, had a fully developed odontoid process. Ossification of the vertebral column is complex but an overview of primary and secondary ossification centers is given below: Primary ossification centers
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