The general relations which the larger vessels of the inguino-femoral region bear to each other and to the superficies, may be referred to in PLATE 27, with practical advantage. The umbilicus, A, indicates pretty generally the level at which the aorta bifurcates on the forepart of the lumbar vertebrae. In the erect, and even in the recumbent posture, the aorta may (especially in emaciated subjects) be felt pulsating under the pressure of the hand; for the vertebrae bear forward the vessel to a level nearly equal with, C C, the anterior superior spinous processes of the iliac bones. If a gunshot were to pass through the abdomen, transversely, from these points, and through B, it would penetrate the aorta at its bifurcation. The line A B coincides with the linea alba. The oblique lines, A D, A D,* indicate the course of the iliac vessels. The point D marks the situation where the spermatic vessels enter the abdomen; and also where the epigastric artery is given off from the external iliac. The most convenient line of incision that can be made for reaching the situation of either of the iliac arteries, is that which ranges from C, the iliac spine, to D, the point where the spermatic cord enters the abdomen. The direct line drawn between D and G marks the course of the femoral artery, and this ranges along the outer border, E, of the saphenous opening. DESCRIPTION OF PLATE 27. A. The umbilicus. B. The upper margin of the pubic symphysis. C. The anterior superior spine of the left iliac bone. C*, the situation of the corresponding part on the right side. D. The point where, in this subject, the cord manifested itself beneath the fibres of the external oblique muscle. D*, a corresponding part on the opposite side. E. The saphenous opening in the fascia lata, receiving e, the saphenous vein. F. The lax and pendulous cord, which in this case, overlies the upper part of the saphenous opening. G. Lymphatic glands lying on the fascia lata in the neighbourhood of the saphenous opening. H. The fleshy part of the external oblique muscle. a a a. The superficial fascia of the abdomen. b. The same fascia forming an envelope for the spermatic cord and scrotum. c. Inguinal glands lying near Poupart's ligament. d. A common venous trunk, formed by branches from the thigh and abdomen, and joining-- e e. The saphenous vein. f. The middle cutaneous nerve, derived from the anterior crural nerve. g. Femoral lymphatic glands. h. Superficial external iliac vein. i. Superficial epigastric vein. k. External cutaneous branches of nerves from the lumbar plexus. [Illustration: Abdomen and leg, showing blood vessels, muscles and other internal organs.] PLATE 27 COMMENTARY ON PLATES 28 & 29. THE SURGICAL DISSECTION OF THE FIRST, SECOND, THIRD, AND FOURTH LAYERS OF THE INGUINAL REGION IN CONNEXION WITH THOSE OF THE THIGH.