The Origin and Distribution of the Nerves to the Lower Limb.

THE following investigation was begun several years ago, with the object of testing the validity of the rules laid down by Herringham (1) for the upper limb, in relation to the distribution of the nerves of the lumbo-sacral plexus to the lower limb; of clearing up certain doubtful points in the anatomy of the plexus and its. relations to the vertebral segments; and of defining, if possible, the exact area of distribution in the lower limb of the several spinal nerves entering into the composition of the plexus. While the work has been in progress,-and, for various reasons, it has been laid aside from time to time, and has only been continued as circumstances permitted,-several important memoirs have appeared, dealing with different aspects of the subject. These have been of the greatest assistance to me in formulating conclusions, confirming observations, and throwing light upon certain obscure points. Ross (2), Thorburn (3), Starr (4), McKenzie (5), and Head (6) have attacked the subject from the clinical standpoint; Eisler (7) has made exhaustive investigations into the anatomy of the plexus, and certain of the branches emanating from it; and Sherrington (8) has made valuable observations on an experimental basis into the distribution of the motor and sensory roots of the spinal nerves supplying the lower limb. To separate individual nerve trunks into their component elements, and to trace to their peripheral terminations the various subdivisions of the constituent spinal nerves, is now recognised as a feasible operation. It must, at the same time, be conceded that the process is difficult and laborious, especially in the case of the smaller nerves of the limb, which may have