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The atlanto-axial joint is a joint in the upper part of the ... It is a pivot joint that provides 40 to 70% of ... the Unity of Form and Function. New York. McGraw ...
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.
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 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 joint space equals the distance between the involved bones of the joint. A joint space narrowing is a sign of either (or both) osteoarthritis and inflammatory degeneration. [12] The normal joint space is at least 2 mm in the hip (at the superior acetabulum), [13] at least 3 mm in the knee, [14] and 4–5 mm in the shoulder joint. [15]
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]
Atlantoaxial instability is a common asymptomatic finding in rheumatoid arthritis patients. [3] However, it can lead to cervical myelopathy . [ 4 ] Patients with atlantoaxial instability can experience neck pain and headaches in the back of the head (occipital headaches).