The lumbar curve forms later from twelve to eighteen months, when the child begins to walk. Surfaces
Anterior surfaceWhen viewed from in front, the width of the bodies of the vertebrae is seen to increase from the second cervical to the first thoracic; there is then a slight diminution in the next three vertebrae. Below this, there is again a gradual and progressive increase in width as low as the sacrovertebral angle. From this point there is a rapid diminution, to the apex of the coccyx. Posterior surfaceFrom behind, the vertebral column presents in the median line the spinous processes. In the cervical region (with the exception of the second and seventh vertebrae), these are short, horizontal, and bifid. In the upper part of the thoracic region they are directed obliquely downward; in the middle they are almost vertical, and in the lower part they are nearly horizontal. In the lumbar region they are nearly horizontal. The spinous processes are separated by considerable intervals in the lumbar region, by narrower intervals in the neck, and are closely approximated in the middle of the thoracic region. Occasionally one of these processes deviates a little from the median line — which can sometimes be indicative of a fracture or a displacement of the spine.
As people usually ignore the cause of their daytime impairments, PLMS during sleep are mostly found through laboratory examination rather than clinical complaints.Video-Polysomnography may be recommended to distinguish PLMS from other leg movements during sleep time which may be similar to PLMS when it comes to duration and pattern. Measures from PSG allocated to the diagnostic of PLMD are essentially based on electromyography (EMG) measuring muscle activity. EMG electrodes are usually placed on anterior tibialis muscle.Recent studies showed actigraphy may be combined to PSG as a screening tool for PLMD diagnosis. Actigraphs are watch-shaped devices - usually worn by adult population on the wrist - used to record sleep and wake periods for at least a week. Recent actigraphy devices allow more precise recordings which helps evaluating if actual movements meet diagnostic criteria for PLMD. Recent studies showed actigraph records reflect quite accurately PLMI criterion.Crucial for the diagnosis are the inter-movement intervals and the frequency of PLMS - each movement must happen within a 4 to 90 second interval from the previous movement. The periodic limb movement index (PLMI), which corresponds to the number of periodic limb movements per hour, must be more than 15 movements per hour in adults and 5 movements or more per hour in children.