annulus fibrosus


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annulus fibrosus

The tough fibrous outer zone of the intervertebral disc that normally retains the soft inner nucleus pulposus. Weakness of the annulus fibrosus allows prolapse of the pulpy centre in the condition inaccurately known as ‘slipped disc’.
References in periodicals archive ?
Stage II-Prolapse: Is a rupture of nucleus pulposus through the annulus fibrosus but not through the posterior longitudinal ligament.
The nucleus pulposus cells, at the centre of the disc, and the annulus fibrosus cells, which populate the IVD "niches," are difficult to reproduce in the laboratory since the unique markers to identify these cells are not known yet [1-4].
The aneurysm of the Valsalva sinus seems to be due to the failure of fusion between the aortic media and the heart at the level of the annulus fibrosus of the aortic valve, with subsequent aneurysmal enlargement at this weak point due to the high head of pressure at the root of the aorta (4).
The maximum stresses on the annulus fibrosus at the upper adjacent level ranged from 0.21 to 0.57 MPa (mean [+ or -] SD: 0.28 [+ or -]0.11 MPa).
Despite its benign nature, occasionally, calcified nucleus pulposus passes the ruptured annulus fibrosus, herniates to the spinal canal, and results in neurological symptoms.
Meanwhile, the nucleus pulposus tissue degenerated in the disc can be thermocoagulated to repair the ruptured annulus fibrosus, which thus reduces the recurrence rate, leaves a small surgical incision and promotes recovery.13,14
* 3rd stage is extrusion where the nucleus pulposus breaks through the annulus fibrosus but still remains within the disc
This syndrome is commonly reported in adult and elderly dogs, mainly in large and giant breeds (NEER, 1992; CAUZINILLE & KORNEGAY, 1996; GANDINI et al., 2003; TESSER et al., 2009), which suggested that predisposing factors, including aging or a fissure of the annulus fibrosus, facilitate entry of nucleus pulposus material into the vasculature (NEER, 1992; CAUZINILLE & KORNEGAY, 1996).
Nucleus pulposus and annulus fibrosus regions were identified, several regions of interest were chosen, and their ADC values were obtained.
The normal aortic valve leaflet was outgoing from structures of the annulus fibrosus formed by dense meshwork of fine collagen fibers (Figure 2).
After that, many groups isolated and identified MSCs from the nucleus pulposus, annulus fibrosus, and cartilage endplate [10, 11, 23-30].
No other injuries were noted including no injury to the posterior longitudinal ligament or posterior annulus fibrosus of C1-2 (Figures 3 and 4).