The clinical examinations of the backs show that in all these cases there was evidence of disturbance in the region of the lower lumbar spine. In the majority of the cases this was substantiated by roentgenologic examination.

Clinical evidence of nerve involvement was found in over half the cases. (Actually in fifteen out of twenty-one.) In many of the cases signs were present which helped to localize the portion of the nerve affected.

The areas of anaesthesia or hyperaesthesia, the changes in the reflexes, and the points of tenderness suggest either the fourth or fifth lumbar roots and the first and second sacral roots as the ones involved. (See Charts.)

The anatomic studies in our opinion show that changes occurring at the lumbo-sacral junction have the greatest possibility of affecting nerve structures. Conditions existing in the intervertebral canal between the fourth and fifth make that the next most likely point for nerve involvement. The solid nature of the sacrum offers little possibility for involvement of the sacral nerves during their exit, and the subsequent course of these nerves is such as to render their involvement unlikely.

We have approached the subject of sciatic pain from four different standpoints: first, anatomical dissections; second, clinical examination of the Spine; third, neurologic examination for localizing evidence; and fourth, roentgenologic examination. It seems to us that the evidence obtained in all the investigations indicates that sciatic pain of the type studied is a symptom of disturbance in the lower lumbar spine and that the site of the lesion is most frequently the lumbo-sacral junction, and the nerve chiefly involved is the fifth lumbar.