Each kidney (Ren) presents two surfaces, two borders, and two
extremities or poles, but they differ so much in form and position as to
require a separate description of each in these respects.[135]
The =right kidney= (Ren dexter) in outline resembles the heart on a
playing card, or an equilateral triangle with the angles rounded off. It
lies ventral to the upper parts of the last two or three ribs and the
tip of the first lumbar transverse process. The =dorsal= (or superior)
=surface= (Facies dorsalis) is strongly convex; it is related chiefly to
the diaphragm, but also to a small extent posteriorly to the psoas
muscles. In well hardened specimens, especially those from thin
subjects, impressions of the last two ribs and the tip of the first
lumbar transverse process are usually visible. The =ventral= (or
inferior) =surface= (Facies ventralis) is in general slightly concave,
and is related to the liver, pancreas, cæcum, and right adrenal; it
either has no peritoneal covering, or only a narrow area externally is
so covered. The =internal border= (Margo medialis) is convex and
rounded; it is related to the right adrenal and the posterior vena cava.
It presents about its middle a deep notch, the =hilus= (Hilus renalis);
this is bounded by rounded margins, and leads into a space termed the
=renal sinus= (Sinus renalis). The vessels and nerves reach the kidney
at the hilus, and the sinus contains the pelvis or dilated origin of the
ureter. The =external border= (Margo lateralis) is rounded, and is
thinner than the internal one. It consists of two parts, anterior and
posterior, which meet at an external angle; the anterior part fits into
the renal impression of the liver. The duodenum curves around the
external border. The =anterior extremity= (Extremitas cranialis), thick
and rounded, lies in the renal impression of the liver. The =posterior
extremity= (Extremitas caudalis) is thinner and narrower.
[Illustration:
FIG. 375.—DIAGRAM OF POSITION AND DORSAL RELATIONS OF KIDNEYS OF
HORSE.
Areas of direct relations are inclosed by continuous lines; parts of
skeleton which overlie the kidneys but are not in contact with them
are indicated by dotted lines. _L.I_-_III_, lumbar transverse
processes.
]
[Illustration: