The =kidneys= are superficially divided into polygonal lobes by fissures
of variable depth. The lobes vary in size, and are commonly about twenty
to twenty-five in number. The fissures are filled with fat.
The =right kidney= has an elongated elliptical outline, and is flattened
dorso-ventrally. It lies ventral to the last rib and the first two or
three lumbar transverse processes. The dorsal surface is rounded, and is
in contact chiefly with the sublumbar muscles. The ventral surface is
less convex, and is related to the liver, pancreas, duodenum, and
terminal part of the colon. The hilus is situated on the anterior part
of this surface near the inner border. The internal border is nearly
straight, and lies parallel with the posterior vena cava. The external
border is convex. The anterior extremity occupies the renal impression
of the liver, and is capped by the adrenal body.
The =left kidney= occupies a remarkable position, and when hardened _in
situ_, differs strongly in form from the right one. When the rumen is
full, it pushes the kidney backward and across the median plane, so that
it is situated on the right side, behind and at a lower level than the
right kidney. It then lies usually under the third, fourth, and fifth
lumbar vertebræ. When the rumen is not full, the left kidney may lie
partly to the left of the median plane. It has three surfaces. The
dorsal surface is convex, and presents on its antero-external part the
hilus, which opens outward. The ventral surface is related to the
intestine. The third face is often more or less flattened by contact
with the rumen, and may be termed the ruminal surface. The anterior
extremity is small, the posterior large and rounded.
[Illustration: