Equine Urinary System - Horse Anatomy
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This article is still under construction. |
Kidneys
The kidneys of the horse are both enclosed in a fat capsule. Dorsally they rest against the psoas muscle and against the diaphragm.
The right kidney is to be found ventrally to, and between, the last 2 ribs and first lumbar transverse process. Cranially it touches the liver and caudally it is attached to the pancreas and the base of caecum. The duodenum winds around its lateral and then ventral surfaces. Medially is the caudal vena cava and adrenal gland.
The left kidney is between the last rib and 3rd transverse process. Its ventral surface is almost completely covered by the peritoneum and contacts the small intestine and and small colon. The spleen contacts it cranioventrally. Medially is the left adrenal glandand aorta.
The Basic Components of the Kidney
Outer fibrous capsule
A tough outer capsule surrounds the parenchyma and this prevents the kidney expanding.
Renal Cortex
The renal cortex is comprised of two parts: the external zone and internal zone (juxtomedullar).
Renal Medulla
The renal medulla contains medullary pyramids. The part nearest the cortex is the base of the pyramid which narrows to form the inner part; the renal papilla. The medulla can be split into two parts, the outer and the inner. Different parts of the nephron reside in these areas
Outer Medulla
The outer medulla can be further divided into the outer and inner stripe
- Outer Stripe: This section located just inside the cortex contains the following parts of the nephron:
- The Inner Stripe: Located inside of the outer stripe this section contains the following parts:
The outer stripe contains the straight proximal tubules and the inner does not. However the inner contains thin ascending limbs and the outer does not. This difference makes up the anatomical demarcation between the two stripes.
Inner Medulla
The inner medulla only contains the following parts:
Renal Pelvis
The renal sinus is located within an indentation on the medial side of the kidney. The renal pelvis is located within the renal sinus. All papillary ducts open into the renal pelvis. The renal pelvis then drains into the ureters. The renal pelvis is lined with transitional epithelium and contains mucous glands in the horse; giving urine a frothy appearence.
Innervation
The kidney receives sympathetic and parasympathetic fibres from the solar plexus. These fibres travel with renal arteries. Sympathetic fibres synapse in coeliac ganglion and cranial mesenteric ganglion.
Lymphatic Drainage
- Renal lymph nodes