OBJECTIVE The blood supply of the lower spinal cord is heavily dependent on the artery of Adamkiewicz, which characteristically originates from one of the thoracolumbar segmental arteries. The aforementioned artery is of enormous clinical, surgical, and radiological importance, and the goal of this study was to elucidate the course and branches of the segmental artery that gives rise to this important vessel. METHODS In this cadaveric, microsurgical anatomical study, the authors investigate and describe the course and branches of the artery of Adamkiewicz and the segmental branch from which it ultimately originates. A review of the literature is provided. CONCLUSIONS By documenting the microsurgical anatomy of these important vessels, this study facilitates an understanding of the anatomy that will aid in treatment planning for surgery of various lesions in this area.