Human spinal arachnoid villi and granulations.

Human spinal arachnoid villi and granulations were studied after distension by a subarachnoid perfusion of Berlin blue and trypan blue. These proliferations were distributed on almost every nerve root in the thoracic and lumbar region. Human spinal arachnoid villi and granulations were divided into those located entirely internal to the dura, those that extended into the dura, and those that penetrated the dura completely. Venous sinuses were closely related to most arachnoid proliferations.