(From the same). The lumbar nerves pass out from the spinal marrow through the vertebrae of the loins, and become larger from the first to the last. The first lumbar nerve throws a large branch backward, and two filaments to the intercostal: the trunk of the nerve goes through the psoas muscle, then to the spine of the os ilium, at whose anterior superior process it throws off several branches to the muscles, and one to the spermatic cord in the male, and to the round ligament of the female. The first going to join the second, sends off two filaments; one of which goes to the spermatic cord, the other passes under the Poupart's ligament to the groin; from this the pain felt in the thigh during a fit of the stone is explained.

The second lumbar nerve lies on the inside of the psoas muscle, goes through its head, and runs along it; then passes through the annular aperture of the obli-quus externus to the scrotum in males, and the labia in women. The second lumbar nerve joins with the third; and that again communicating with the fourth, forms the crural nerve. See Cruraus.

The fourth and fifth lumbar nerves, and the three first sacral, form the sciatic nerve, which, passing out at the great sciatic notch, runs down between thetuber-culum ischii and trochanter major, along the internal and posterior part of the thigh, between the biceps and seminervosus, as far as the ham, rather nearer the inner condyle of the os femoris than the outer. See Cauda equina.

Lumbares arteriae go out posteriorly from the inferior descending aorta, in five or six pair, in the same manner as the intercostals. The upper ones send branches to the neighbouring parts of the diaphragm and intercostal muscles, and supply the place of semi-intercostal arteries; they are also distributed to the psoas, and other adjacent muscles; and, by perforating the oblique muscle, they become external hypogastric arteries. They also go to the vertebral muscles, and enter the spinal canal.

Lumbares venae . proceed from the vena cava, near the bifurcation, and principally on the right side; sometimes from the left iliac vein; this branch communicates with the azygos and intercostal veins.