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The atlanto-occipital joint may be dislocated, especially from violent accidents such as traffic collisions. [1] This may be diagnosed using CT scans or magnetic resonance imaging of the head and neck. [1] Surgery may be used to fix the joint and any associated bone fractures. [1] Neck movement may be reduced long after this injury. [1]
The atlanto-occipital joint allows the head to nod up and down on the vertebral column. The dens acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side. The atlas's chief peculiarity is that it has no body, [3] which has fused with the next vertebra. [4]
The under surface of the jugular process is rough, and gives attachment to the Rectus capitis lateralis muscle and the lateral atlanto-occipital ligament; from this surface an eminence, the paramastoid process, sometimes projects downward, and may be of sufficient length to reach, and articulate with, the transverse process of the atlas.
The occipital condyles are undersurface protuberances of the occipital bone in vertebrates, which function in articulation with the superior facets of the atlas vertebra.. The condyles are oval or reniform (kidney-shaped) in shape, and their anterior extremities, directed forward and medialward, are closer together than their posterior, and encroach on the basilar portion of the bone; the ...
The anterior atlantoaxial ligament is a strong membrane, fixed above the lower border of the anterior arch of the atlas; below, to the front of the body of the axis.. It is strengthened in the middle line by a rounded cord, which connects the tubercle on the anterior arch of the atlas to the body of the axis.
The cruciate ligament of the atlas (cruciform ligament) is a cross-shaped (thus the name) ligament in the neck forming part of the atlanto-axial joint. It consists of the transverse ligament of atlas, a superior longitudinal band, and an inferior longitudinal band. The cruciate ligament of the atlas prevents abnormal movement of the atlanto ...
The median atlanto-axial joint is sometimes considered a triple joint: [3] one between the posterior surface of the anterior arch of atlas and the front of the odontoid process; one between the anterior surface of the ligament and the back of the odontoid process; The lateral atlantoaxial joint involves the lateral mass of atlas and axis. [4]
The distance between the atlas and the occipital condyles, the atlanto-occipital interval (AOI), should measure less than 4 mm, and is better assessed on coronal images. [ 4 ] The Powers ratio was formerly used, which was the tip of the basion to the spinolaminar line, divided by the distance from the tip of the opisthion to the midpoint of the ...