The circumference of the kidney presents, 1st, an external border, thick, convex, semi elliptical, and directed outwards, backwards, and upwards ; 2nd, an internal border, directed inwards, forwards, and downwards, and pre senting about its middle a deep notch or fissure, the hilum, as it is sometimes called. This notch is more marked posteriorly, where it corresponds to the commencement of the ureter and the pelvis of the kidney, than an teriorly, where it corresponds to the renal vein. The notch usually contains some adi pose tissue, which passes in with the blood vessels, and occupies the space between the substance of the kidney and the pelvis.
Of the extremities of the kidney, the su perior, as before stated, is larger than the inferior, and directed somewhat inwards. It is immediately covered by the supra-renal capsule. The liver is above the right, and the spleen above the left. The inferior extremity of the kidney is directed somewhat outwards, and has below it, but at some distance from it, the crest of the ilium.
The ureter, or excretory duct of the kidney, extends from the hilum of this organ to the base of the bladder. It is a cylindrical canal, with whitish, elastic walls, varying in size from that of a crow-quill to that of a goose-quill. It is usually dilated at its commencement, narrowed in the middle of its course, and again dilated before its entrance into the bladder.
Its direction is obliquely downwards and inwards to the sides of the base of the sacrum; it then passes almost horizontally forwards between the layers of peritoneum forming the posterior ligament of the bladder ; lastly it is directed inwards to the side of the base of the bladder, where it takes an oblique course through the wall of that organ, to open on its inner surface by a narrow orifice in one of the posterior angles of the trigone.
The relations of the ureter are the following : — In the notch of the kidney the ureter lies behind the renal vessels. From the pelvis of the kidney to the base of the sacrum it is in contact with the anterior border of the psoas muscle ; it is covered by the peritoneum, and is crossed obliquely by the spertnatic vessels. The right ureter has the inferior vena cava on its inner side. On a level with the base of the sacrum, each ureter crosses the common iliac, and below this the external iliac artery and vein. In the pelvis the ureter lies in contact with the wall of this cavity, being covered by peritonmum, and crossing successively the umbilical artery or its ob literated cord, the obturator vessels, the vas deferens in the male, and the superior and lateral part of the vagina in the female. In
that part of its course which is included in the wall of the bladder the ureter is very close upon the neck of the uterus, and is thus liable to become involved in cancerous disease of that organ.* That part of the ureter which lies in contact with the anterior border of the psoas may become affected by disease ex tending from the substance of the muscle. The pathological museum of King's College contains a preparation in which an abscess, occupying the substance of the psoas muscle, has opened into the ureter.
The ureter has two distinct coats or mem branes. 1. An internal mucous membrane, continuous above with the mucous lining of the pelvis of the kidney, and below with that of the bladder. 2. An external fibrous coat, continuous above with tbe capsule of the kidney and with the pelvis, and below with the muscular coat of the bladder. The minute structure of the coats of the ureter mill be described in a subsequent part of this article.
Blood-vessels of the Kidney. —The emulgent± or renal arteries are the largest branches of the abdominal aorta, from which they.proceed at nearly a right angle. Their origin is about half an inch below the superior mesenteric artery, the right being frequently somewhat lower and longer than the left. Each renal artery passes obliquely downwards, backwards, and outwards towards the hilum of the kidney, giving off in its course branches to the supra renal capsule, to the ureter, and to the sur rounding cellular membrane. At the pelvis of the kidney the artery usually lies be tween the vein and the ureter, the former being in front of, and the latter behind, the artery. In the hilum of the kidney, where the artery is surrounded by reticular and adipose tissue, it breaks up into four or five branches, and these again subdivide into smaller branches, most of which pass in front of the pelvis of the kidney, while a smaller number pass be hind this part ; their course and distribution in the substance of the kidney- will be de scribed in connexion with the structure of the gland. The right renal artery is covered at first by the vena cava, and then by its corresponding vein ; the duodenum and pan creas are also in front of it. It crosses the spine and the right psoas muscle. The artery on the left side is covered by its corresponding vein, and crosses the left psoas muscle.