[Location] Localized in the erect sitting position or prostrate position, or in the lateral recumbent position. On the head, posterior to the auricle, in the depression posterior and inferior to the mastoid process. (Fig.50)
 
[Regional Anatomy] Skin→subcutaneous tissue→the stermocleidomastoid→splenius muscle of head →muscle of head. Superficial layer, the minor occipital nerve, the branches or the subordiantial ramus of the posterior auricular artery and vein; deep  layer, the deep carotid artery and vein. It can be punctured at the vertebral artery if you insert deeply.