Pain medicine : the official journal of the American Academy of Pain Medicine
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To define the source and the course of the articular branches to the midthoracic zygapophysial ("z") joints. ⋯ Articular branches to the T4-T8 z-joints have substantial inter- and intraspecimen variability of origin. They typically arise from the dorsal ramus rather than the medial branch and frequently do not contact any osseous structure to allow percutaneous needle placement.