The course of the occipital artery - An anatomical investigation for biopsy in suspected vasculitis

Background: The occipital artery can show an inflammation in cranial arteri tis. For biopsy it is essential to know the course of the occipital artery. Methods: In 6 randomly selected specimens of the head, the occipital artery and vein were sought and examined. In addition, the topographical proximit y of the greater occipital nerve was considered. Results: Course: The occipital artery followed a tortuous course, including an occasional hairpin bend in four out of 6 specimens. Lateral distance of the occipital artery from the external occipital protuberance of the occip ut: The occipital artery runs at a mean distance of 3.92 cm on the right si de and 4.4 cm on the left side from the midline. Variations of the course: A comparison between the right and left side showed a marked side-differenc e in the course of the vessel. The extent of tortuosity varied distinctly. In most of the arteries, the angle between superior nuchal line and occipit al artery was 90 degrees. External diameter: The average external diameter of the occipital artery (in the area where it crosses with the superior nuc hal line) was 2.3 mm on the right side and 2.7 mm on the left side. Conclusion: Because the greater occipital nerve enters the subcutis below t he external protuberance of the occiput and shortly afterwards crosses the occipital artery, we recommend to carry out the biopsy of the occipital art ery between 1 to 3 cm above (cranially) and 4 to 5 cm lateral to the extern al protuberance.