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

BACKGROUND: The occipital artery can show an inflammation in cranial arteritis. 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 proximity of the greater occipital nerve was considered. 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 occiput: The occipital artery runs at a mean distance of 3.92 cm on the right side 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-difference in the course of the vessel. The extent of tortuosity varied distinctly. In most of the arteries, the angle between superior nuchal line and occipital artery was 90 degrees. External diameter: The average external diameter of the occipital artery (in the area where it crosses with the superior nuchal 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 the external protuberance of the occiput and shortly afterwards crosses the occipital artery, we recommend to carry out the biopsy of the occipital artery between 1 to 3 cm above (cranially) and 4 to 5 cm lateral to the external protuberance.