78 ESSAY ON THE DESCRIPTIVE ANATOMY OF THE 
all directions, so as to reach the cortical substance, abruptly 
dividing into numerous branches, which eventually subdivide to 
form capillaries. By this it is evident that the cortical sub¬ 
stance is more vascular than the medullary, indeed the latter 
is very scantily supplied with arterial blood. 
From the arterial terminations the venous origins occur, and 
these unite to form branches, having a similar arrangement as 
the arteries; only as they reach the pelvis, almost opposite the 
apex, they meet to form a wide capacious trunk, the renal vein. 
This is supplied with valves, not all of which are perfect. At 
the opening of each renal vein into the cava is a semi-lunar 
flap overlapping the posterior part. 
The nerves of kidneys are numerous, and derived from the 
renal plexuses of the sympathetic: they accompany the vessels 
with which they penetrate their respective organs. 
Lymphatics may be seen issuing from the hilus of the 
kidney ; they enter some lymphatic glands there situate, and 
then convey the lymph into the receptaculum chyli. 
Supra Renal Capsules. 
These bodies, also called capsulse supra-renales, seu atra- 
bilarise, are two in number, and belong to the class vascular 
glands, whose office is very indefinitely known. 
They are situated one on each side of the spine, across the 
direction of the renal vessels. Their attachments are effected 
by vessels as well as by the peritoneum on their inferior sur¬ 
face, connecting them to the corresponding kidney and around 
to the spine. 
The shape of the supra-renal bodies is much the same on 
either side, being that of a slightly bent ellipsis. They vary 
from three to four inches in length, and from one-and-a-half to 
two inches in breadth. 
Their concave border corresponds to the renal vessels, as well 
as to the anterior mesenteric arteries. The convex border is in 
contact with the inner margin of the kidney. The anterior 
extremity of the right one is in connexion with the right 
hepatic lobe, whilst its inferior surface is in connexion with the 
commencement of the colon. The left supra-renal capsule is 
related anteriorly to the pancreas, and inferiorly to the trans¬ 
verse colon. 
The peritoneal coat of the supra-renal capsules is merely 
confined to their inferior surface. The proper substance of the 
organ is enclosed in a fibrous or albugineous coat, which forms 
a distinct covering externally, and becomes continuous as sheaths 
to vessels internallv. 
