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lateral side of the quadratus lumborum muscle. The lateral border is narrowest above, and widest just below its middle point, corresponding to the greater thickness of the kidney at this level.

In many ways it would be more satisfactory to apply the term facies muscularis or muscular surface collectively to the areas above described as "posterior surface" and “lateral border"; in like manner the term facies visceralis, or visceral surface, might be suitably applied to the so-called anterior surface of the organ. The edge separating the visceral from the muscular surface is the actual lateral edge or border of the kidney.

Anterior Relations and the Anterior Surface of the Kidney.-The anterior relations of the kidneys not only differ on the two sides of the body, but also many

Inferior vena cava
Right inferior phrenic artery | Coeliac artery
Right suprarenal gland

Superior mesenteric artery
Right renal vein

Left crus of diaphragm
Genito-femoral nerve

Medial lumbo costal arch
Right ureter

Internal spermatic vein

Psoas major
Ilio-hypogastric nerve

Lateral lumbo-costal arch Nio-inguinal nerve

Quadratus lumborum

Transversus abdominis

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Lateral cutaneous nerve of thigh

External iliac artery

External iliac artery
Hypogastric artery

Hypogastric artery
Common iliac artery
Internal spermatic artery

Inferior mesenteric artery

of the structures related to the anterior surface of each kidney undergo frequent
changes in position during life. Hence it is not possible to give more than a
general account of the anterior relationships of the kidneys.

Right Kidney.-A small area on the superior part of the anterior surface of the right kidney is in relation to the corresponding suprarenal gland (Fig. 983). The rest of the superior part of the anterior surface is in contact with the visceral surface of the liver, which is often hollowed out to form a fossa for the kidney. The suprarenal gland is bound to the kidney by connective tissue, while the part of the kidney in relation to the liver is, like the liver itself, covered by peritoneum, and thus the two organs, although closely applied, are really separated by a part of the general peritoneal cavity. Immediately anterior to the inferior end of the right kidney are usually found two parts of the alimentary canal-namely, the descending part of the duodenum and the right flexure of the colon, or the

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cement of the transverse colon. The part of the kidney related to the
m lies to the medial side of the area which touches the colon, but the exact
of the kidney in contact with each of these two parts of intestine varies
different subjects. Frequently the colon and the kidney are both covered
oneum where they are in contact, but the duodenum is bound down to the
y connective tissue. In addition to the structures mentioned, some portion
eum, or of the jejunum, is often found in contact with a small part of the
ney near its inferior end.
me cases the peritoneal membrane does not cover the whole of the surface
t with the liver, and then the superior part of the hepatic area of the
, like the anterior aspect of the suprarenal gland, bound by connective
the "uncovered” area on the posterior aspect of the liver.

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ERIOR ASPECT OF THE KIDNEYS AND GREAT VESSELS. The drawing was made, before of the organs, from a specimen in which the viscera had been hardened in situ. The dotted lines the areas which were in contact with the various other abdominal viscera.

ney.-The extreme superior and medial part of the anterior aspect of ney is united by connective tissue to the lower part of the left supraand the area immediately below this is in contact with the stomach Creas. The pancreas, like the suprarenal gland, is bound down to the nective tissue, but the stomach is separated from the area with which sition by a portion of the omental bursa. The area in actual contact nach is a small somewhat triangular district situated above the level pancreas is related to the kidney. The superior and lateral part of the et of the kidney is related to the spleen, the two organs being separated of the general peritoneal cavity, except along the area where spleen re connected by the lieno-renal ligament. The anterior surface of nd of the left kidney is related, towards the medial side, to a part of and, towards the lateral side, to the left flexure of the colon or to a lescending portion of the colon. In most cases, however, the colon he posterior abdominal wall to the lateral side rather than on the ce of the left kidney.


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The right and left colic arteries, or their branches, as they pass laterally to reach the colon, are often related to the anterior aspects of the corresponding kidneys. The splenie vessels pass laterally in front of the left kidney (Fig. 979).

The anterior surface of a kidney which has been hardened in situ is, like the posterior surface, not uniformly rounded, but marked by a series of impressions corresponding to the different structures which lie in contact with it. In the case of each kidney, the most prominent region on the anterior surface lies below the level of the middle of the kidney, and corresponds to the thickest part of the organ.

Cortical substance of kidney

From this promin-
ence on the anterior
surface a series of
more or less flattened
planes slope away to-
wards the borders of

the kidney. These

flattened areas are the
impressions formed
by the viscera which
lie on the anterior

surface of the Basal part

kidney. of pyramid

In the case of the

right kidney, three Papillæ

impressions can usuSinus of kidney

ally be distinguished on the anterior surface. One occupies the whole of the upper part of the organ, and is known as the impressio he

patica; another Branch of renal artery

stretches from the
+--- Pyramid

most prominent point
to the inferior end of
the kidney, and is
related to the colon;

while the third ex. Radiate part (“medullary rays ") of cortex


medial margin, below

the hilum, and is in The vessels and fat have been removed to give a view of the wall of the kidney contact with the

sinus. The points where the vessels enter the kidney substance are seen as
holes in the sinus wall.

second part of the

duodenum (Fig. 979) The relative sizes of these three areas or impressions vary much in different specimens.

On the left kidney, also, three more or less defined, flattened impressions slope towards the borders of the organ from the most prominent part of the anterior surface. One of these, on the superior and lateral part of the kidney, is the splenic impression; another, extending downwards to the lower end of the kidney, is for the jejunum, or for the jejunum and colon; the third, above and in the region of the hilum, is called the impressio gastrica, and corresponds to the position of the overlying stomach. Only a small portion of this impression is in direct contact with the stomach, since the pancreas and a part of the suprarenal gland intervene between the stomach and the kidney (Fig. 979).

It is common to find the left kidney thicker and less flattened antero-posteriorly than the right, the impressions, or "facets," upon its surface being at the same time better marked. With this probably is to be associated the fact that floating kidney is more rarely met with on the left than on the right side of the body.


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bases of rm-nal colt the kidne e granul ned the siand ligh more uni In sectios tend the - an brapa

In the surface


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tremities of the Kidney.—The kidney, fixed and hardened in situ, is usually pointed at its inferior than at its superior end. The latter is wider from

side, and often somewhat flattened from before backwards. The superior the kidney is bent somewhat forwards and rests upon the diaphragm, which es it from the inferior part of the pleural cavity. us Renalis.—The sinus of the kidney (Fig. 985), into which the hilum opens, rrow space, having its long axis corresponding to that of the kidney. The alls of the sinus cavity are formed by the substance of the kidney, and are lined rt of the fibrous kidney capsule which enters the sinus over the lips of the

The floor of the sinus is not even, but presents a series of small projecting elevations called papillæ renales, which vary from six to fifteen in number. ig from each papilla are a number of somewhat raised bars, or ridges, of ubstance, separated by depressed areas. The blood-vessels and nerves enter e the kidney by piercing the wall of the sinus where it is formed by these pressed areas (Fig. 985). The rounded summit of each renal papilla is y a number of minute openings called foramina papillaria, which are the apertures of the secreting tubules of which the kidney is mainly comThese openings all lie close together, and give rise to the so-called area upon the apex of the renal papilla. The urine secreted by the kidney hrough the foramina papillaria into the subdivisions (or calyces) of the kidney duct. ey in Section.-Sections through the kidney (Fig. 985) show that it ed to a large extent of a number of conical masses, known as pyramides

pyramids. These together constitute the substantia medullaris or medulla Iney, and are arranged with their bases directed towards the surface, and es projecting into the renal sinus, where they form the papillæ renales entioned. The pyramids are more numerous than the papillæ, two or illy ending in each papilla in the middle part of the kidney, and someany as six or more in each papilla near the superior and inferior ends an. The bases of the pyramids do not reach the surface of the kidney, barated from it by a thin layer of kidney substance called the cortex, cia corticalis of the kidney. The cortical substance not only covers over of the pyramids, but also sends in prolongations, called columnæ renales lumns, between the pyramids, towards the sinus. The medullary part ey exhibits in section a striated appearance, while the cortical part is ular and usually different in colour. The outer part of each pyramid is basis pyramidis, and appears in section to be composed of alternate ht streaks, while the inner, or papillary part, is often of a lighter colour, niformly and faintly striated. ons of the kidney the larger blood vessels are seen, after they have

kidney substance, to lie between the pyramids; and some of their nes are visible passing across the bases of the pyramids. tus and young child, and sometimes, though much less distinctly, in the adult,

the kidney is marked by a number of grooves dividing it into polygonal e represent the lobes, lobi renales or reniculi, of which the kidney is posed, and each corresponds to one papilla with its pyramids and surrounding ance. ination, with an ordinary pocket lens, of a section through the kidney he lighter striæ of the bases of the pyramids are continued into the they pass through the cortex towards the surface of the kidney the

less distinct, and appear, when cut longitudinally, as separate raytions carried outward from the bases of the pyramids. These parts s, which seem, in this way, to be continuations of the medulla, edullary rays” and constitute the pars radiata ; the portions which ween them form what is known as the pars convoluta or “ labyrinth.” ce presented by the cortex of the kidney in section varies much the plane in which the section has been taken. If the section h and lies parallel to the axis of a pyramid, the radiate part met

Pars convoluta

Pars radiata

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with will appear as isolated streaks directed from the base of the pyramid towards the surface of the kidney, and separated from one another by narrow strips, or intervals, of the convoluted part. On the other hand, in sections made at right angles to the axis of a pyramid, or cutting this axis obliquely, the convoluted

portion of the cortex presents the appearance of a continuous net,

the meshes of which are occupied Corpuscle of by the radiate parts, and -the kidney

these latter now exhibit a circular or Pars

oval outline. In a similar manner Interlobular sections through the bases of the artery Corpuscu

pyramids differ much in the appearlum renis

ances they afford according to the (glomerulus) Arciform plane in which they are cut.

Kidney Tubules.—Theglandular substance of the kidney is composed of a vast number of minute tubules,

called tubuli renales or uriniferous Collecting tubules, all of which have an exceed

ingly complicated course. The wall

of each tubule consists throughout of Loop of

a basement membrane and of an

epithelial lining, but the lumen of glomerular

the tubule and the character of the Afferent glomerular

epithelium vary much in its different parts. Every tubule begins in a thin

walled spherical dilatation, known as Capsule

capsula glomeruli (0.T. Bowman's


of capillary blood vessels is contained

. In the middle part of the figure the course of one of the kidney

The tuft of capillaries is covered by a tubules is indicated, and in the lateral parts the disposition of the larger arteries. A, Cortex ; B, Basal portion; capsule, and is, as it were, in vaginated

and C, Papillary portion of pyramid. The diagram at the right-hand side of the lower part of the capsules with their enclosed capillaries

into the capsule (Fig. 986). The posing a renal corpuscle. in the convoluted portion of the kidney cortex, where they may be recognised as minute

ney corpuscles, and are all placed red points just visible to the unaided eye and best marked when the renal vessels are con gested. The part of the tubule leading from the capsule—first convoluted tubule tortuous, and lies within the convoluted part of the cortex. Passing from the con voluted part, the tubule enters a radiate part, in which its course becomes less complicated, and here it receives the name of spiral tubule. From the radiate part the tubule enters the basal portion of the pyramid, and, diminishing in diameter, it pursues a straight course Within the apical portion of the pyramid the tubule suddenly bends upon itself. forming towards the apex of the pyramid, forming the so-called descending limb of Herele's loop. pyramid into the radiate part of the cortex as the ascending limb of Henle's loopascending limb exhibits a slight spiral twisting. Leaving the radiate part, the tubule once more enters the convoluted part of the cortex, where its outline becomes so that the name irregular tubule is applied to it. While still within the convoluted part, its contour having acquired a more uniform appearance, the tubule receives the name of second convoluted tubule; this latter finally ends in a short junctional tubule, which passes back into a radiate part of the cortex and joins a collecting tube. Each collecting tube receives numerous kidney tubules, and pursues a straight course through the radiate part an excretory tube, which opens on the summit of a renal papilla into a calyx of the ureter by one of the foramina papillaria already described. In microscopic sections the portions of the kidney tubule may be distinguished by the position which they occupy and by the character of the lining epithelium. substance of the kidney are all united together by a very small amount of connective

Connective Tissue of the Kidney.-The tubules and the blood vessels forming the


-is very






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