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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 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 ...
Examples of a pivot joint include: Proximal radioulnar joint; Distal radioulnar joint; Median atlanto-axial joint; In contrast, spherical joints (or ball and socket joints) such as the hip joint permit rotation and all other directional movement, while pivot joints only permit rotation.
Although the anterior subluxation of the atlantoaxial joint is the most common manifestation of the disorder, subluxation can also occur with posterior or vertical movement, and subaxial (below C2) joints can also be involved. [1] [2]
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.
Excessive laxity of the posterior transverse ligament can lead to atlantoaxial instability, a common complication in patients with Down Syndrome and Ehlers–Danlos syndrome. Laxity has also been hypothesized as the cause of degenerative hypertrophy and mechanical atlantoaxial stress. [3]
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]
Another structure of this type in human anatomy is the cruciate ligament of the dens of the atlas vertebra, also called "cruciform ligament of the atlas", a ligament in the neck forming part of the atlanto-axial joint. [2]